Re: How to make project with main application and cli application in the same folder?
On Sunday, 21 April 2024 at 16:41:08 UTC, Mike Parker wrote:
On Sunday, 21 April 2024 at 08:44:38 UTC, alex wrote:
Hi guys. Trying to play with vibe-d and want to create
separate web app, and cli app which can add admin users. When
I just keep both files app.d and cli.d in source folder, I get
an error that I can't have more then 1 main function.
You can do this using configurations. Whichever you list first
will be the default. Then you can use `-c configName` or
`--config=configName` to build the other one.
You'll want to exclude one of the main functions when building
the configuration to which it doesn't belong. You can do that
with version specifications (e.g., add a `cli` version in the
cli configuration, then `vesrion(cli) void main {...}` in the
code). Alternatively, if the files the main functions are in
are self-contained, then you can just exclude the one you don't
need in each configuration with the `excludeSourceFiles`
directive.
Configurations:
https://dub.pm/dub-guide/recipe/#configurations
Thanks, that really helped me.
For everyone who has the same trouble I can attach my working
solution based on sub packages and configurations. Here is my
dub.json:
```json
{
"name": "cool",
"subPackages": [
{
"name": "app",
"sourcePaths": ["source"],
"mainSourceFile": "source/app.d",
"targetType": "executable",
"configurations": [
{
"name": "app",
"targetType": "executable",
"versions": ["app"]
}
]
},
{
"name": "cli",
"sourcePaths": ["source"],
"mainSourceFile": "source/cli.d",
"targetType": "executable",
"configurations": [
{
"name": "cli",
"targetType": "executable",
"versions": ["cli"]
}
]
}
]
}
```
Main functions:
app.d:
```d
version(app)
void main() {...}
```
cli.d:
```d
version(cli)
void main() {...}
```
And here how I run/build it:
```make
dub run :cli
dub run :app
```
OR
```make
dub build :cli
dub build :app
```
During building, it will create executable like
"{name_of_project}_app" or "{name_of_project}_cli".
How to make project with main application and cli application in the same folder?
Hi guys. Trying to play with vibe-d and want to create separate
web app, and cli app which can add admin users. When I just keep
both files app.d and cli.d in source folder, I get an error that
I can't have more then 1 main function.
I already asked chatGPT, and it replied that I need to use
subpackages. I put cli into separate folder, and now I get an
error, that it can't see some model from main app(I want to reuse
UserModel for both, cli and web app). How can I make it visible
for both cli and web without making copy?
My folder:
project
| -- dub.json
| -- source/
| -- app.d
| -- user_model.d
| -- cli/
| -- source
| -- cli.d
dub.json:
{
"name": "project",
"subPackages": [
{
"name": "app",
"sourcePaths": ["source"],
"mainSourceFile": "source/app.d",
"targetType": "executable",
"dependencies": {
"vibe-d": "~>0.9"
}
},
{
"name": "cli",
"sourcePaths": ["cli/source"],
"mainSourceFile": "cli/source/cli.d",
"targetType": "executable",
"dependencies": {
"vibe-d": "~>0.9"
}
}
]
}
Re: Type sniffing at runtime
On Saturday, 16 May 2020 at 05:22:49 UTC, n0den1te wrote:
[...]
For example, like this:
´´´
import std;
alias types = AliasSeq!(
bool, byte, ubyte, short, ushort, int, uint, long, ulong,
float, double, real, char, wchar, dchar
);
void main()
{
static foreach(type; types)
{
sniffType!type;
}
}
void sniffType(T)() {
writeln("Type : ", T.stringof);
writeln("Length in bytes: ", T.sizeof);
static if(__traits(compiles, T.min))
writeln("Minimum value : ", T.min);
writeln("Maximum value : ", T.max);
writeln("Initial value : ", T.init);
}
´´´
However, for the char, wchar and dchar types the results of min,
max and init are somewhat cumbersome. And T.min does not compile
for the floating point types.
Re: Option and Result [was Integration tests]
On Tuesday, 21 April 2020 at 16:30:15 UTC, Russel Winder wrote: On Mon, 2020-04-20 at 20:19 +, aliak via Digitalmars-d-learn wrote: […] [0]: https://github.com/aliak00/optional Rust has Option and Result, and most languages are rapidly introducing at least Option if not Result – and yes it is almost certain all this comes from Haskell. Is Option intended for adding to Phobos? There is Nullable in Phobos. This is not really an Option, I know. But just in case. But back to integration tests, there are indeed only few possibilities to mock something. However, the basics are there. I found a section of code generation a while ago in std.typecons. https://dlang.org/library/std/typecons.html There are Black and White holes there, for example, which could help to implement a basic mocking framework.
Re: need help to get member function const address
On Thursday, 19 March 2020 at 04:30:32 UTC, Calvin P wrote:
I use this code to get member function address on runtime:
=
struct A {
this(){};
}
auto ctor = (&__traits(getMember, A.init,"__ctor")).funcptr;
=
my question is, how to get it in compile time like static
function address:
=
struct A {
void d(){};
static void fn(){};
}
enum FN = // static method address is ok
enum A0 = &(A.d).funcptr; // Error: need this for d of type
void()
enum A1 = (&__traits(getMember, A,"d")).funcptr; // Error: no
property funcptr for type void function()
enum A2 = (&__traits(getMember, A.init,"d")).funcptr; //
Error: (().d).funcptr cannot be evaluated at compile time
=
A non-static member method can use the context of the struct
where it is defined in. E.g. it could alter a member variable.
This context has to be constructed at run time (and there could
be many instances of the context) and does not exist in compile
time. Therefore the difference to the static method.
Re: What type does byGrapheme() return?
On Monday, 6 January 2020 at 08:39:19 UTC, Robert M. Münch wrote: On 2020-01-05 04:18:34 +, H. S. Teoh said: At a minimum, I think we should file a bug report to investigate whether Grapheme.opSlice can be implemented differently, such that we avoid this obscure referential behaviour that makes it hard to work with in complex code. I'm not sure if this is possible, but IMO we should at least investigate the possibilities. Done... my first bug report :-) I copied togehter all the findings from this thread. For the sake of completeness https://issues.dlang.org/show_bug.cgi?id=20483
Re: Multi-threaded sorting of text file
On Saturday, 4 January 2020 at 07:51:49 UTC, MGW wrote: Need help: There' s a large text file (hundreds of thousands of lines). The structure is as follows: 2345|wedwededwedwedwe .. 872625|rfrferwewweww . 23|rergrferfefer It is necessary to sort this file by the first field having received: 23|rergrferfefer... 2345|wedwededwedwedwe... 872625|rfrferwewweww... There are also N CPU (from 4 to 8) and 16 Gb of Memory. Necessary come up with an algorithm in D for fast sorting using multithreading. As far as I know, there isn't any native in D. Maybe I overlooked some at code.dlang.org. But there are plenty out there in the wild. Found this on the first shoot: https://stackoverflow.com/questions/23531625/multithreaded-sorting-application/23532317
Re: array of functions/delegates
On Tuesday, 24 December 2019 at 07:37:02 UTC, Rumbu wrote:
I am trying to create an array of functions inside a struct.
struct S {
void f1() {}
void f2() {}
alias Func = void function();
immutable Func[2] = [, ]
}
What I got: Error: non-constant expression ''
Tried also with delegates (since I am in a struct context but I
got: no `this` to create delegate `f1`.
So, is there any way to have an array of functions without
adding them at runtime?
If you don't need runtime, probably like this:
´´´
import std;
void f1(S s) {assert(1);}
void f2(S s) {assert(1);}
alias field = AliasSeq!(f1, f2);
struct S{}
void main()
{
S s;
field[0](s);
}
´´´
Don't know why UCFS doesn't work in this case though.
Maybe, this is also helpful:
https://forum.dlang.org/post/mailman.2415.1354291433.5162.digitalmars-d-le...@puremagic.com
Re: Intersection of two sets
On Tuesday, 3 December 2019 at 13:43:26 UTC, Jan Hönig wrote:
It seems i don't google the right keywords.
What i want to do: I have two sets. (I didn't find how to do
sets, so i have two associative boolean arrays
`bool[]`). And i want to join them, via an
intersection.
I know how to code this. Loop over one AA, if the key is also
in the other one, we add that to the third array which is going
to be returned.
pseudocode:
alias set = bool[]
set foo = ...
set bar = ...
set result;
foreach(key; foo)
{
if (key in bar)
{
result[key] = true;
}
}
return result;
1) Is there a better way for creating a set, other then `alias
set = bool[keyClass]`?
This depends on the available accesses on your sets. In terms of
ranges:
Are your sets InputRanges, ForwardRange, ... ?
2) Are there some build-in function for handling such sets?
This is maybe what you are looking for:
https://dlang.org/phobos/std_algorithm_setops.html
Re: Simple casting?
On Tuesday, 26 November 2019 at 05:17:54 UTC, Taylor R Hillegeist
wrote:
On Tuesday, 26 November 2019 at 05:05:48 UTC, Taylor R
Hillegeist wrote:
I'm attempting to do a segment group.
details:
alias ProbePoint[3]=triple;
triple[] irqSortedSet = UniqueTriples.keys
.sort!("a[1].irqid <
b[1].irqid",SwapStrategy.stable)
.array;
83:triple[][] irqSortedSets = irqSortedSet.chunkBy!((a,b) =>
a[1].irqid == b[1].irqid);
GetAllTriplesExtractFileIrqSplit.d(83): Error: cannot
implicitly convert expression `chunkBy(irqSortedSet)` of type
`ChunkByImpl!(__lambda4, ProbePoint[3][])` to
`ProbePoint[3][][]`
I have something that looks like a triple[][] but I can't seem
to get that type out.
when I add .array it converts to a Group which doesn't make
sense to me because I'm not using a unary comparison. Any
thought?
a simpler example:
import std.algorithm.comparison : equal;
import std.array;
// Grouping by particular attribute of each element:
uint[3][] data = [
[1, 1,0],
[1, 2,0],
[2, 2,0],
[2, 3,0]
];
uint[3][][] r1 = data.chunkBy!((a,b) => a[0] == b[0]);
fails in the same way.
What exactly is the problem, as this works for me if I understood
your goal correctly:
´´´
void main()
{
import std.algorithm.comparison : equal;
import std.array;
import std;
// Grouping by particular attribute of each element:
uint[3][] data = [
[1, 1,0],
[1, 2,0],
[2, 2,0],
[2, 3,0]
];
auto r1 = data.chunkBy!((a,b) => a[0] == b[0]);
}
´´´
If it is the type of the return value --> the return value of
chunkBy has a different one compared to the input. Instead, you
get an abstracted range whereas the input data serves as a source.
Re: Splitting a stream of data on based on data change.
On Thursday, 21 November 2019 at 21:36:08 UTC, Taylor R
Hillegeist wrote:
I was looking through the standard library for a good way to
split a range into several ranges based on value changes in the
stream:
AAABB
would be split on the AB transition into:
AAA BB
I just couldn't figure out an elegant way to do it? Any ideas?
Like this?
´´´
void main()
{
import std;
"AAABB"
.chunkBy!((a,b) => a == b)
.writeln;
}
´´´
https://dlang.org/library/std/algorithm/iteration/group.html
https://dlang.org/library/std/algorithm/iteration/chunk_by.html
Re: Unable to pass a D function member to a C callback
On Saturday, 2 November 2019 at 17:49:09 UTC, Luh wrote:
Hello,
When trying to pass a D function to the C callback, the
compiler says:
'Error: cannot implicitly convert expression
of type extern (C) bool delegate(const(short*) a, ulong b,
void* c) to extern (C) bool function(const(short*), ulong,
void*'
because my function is member of a class (compiles when the
function is out of the class).
Is there any way to say to solve this ?
The wiki isn't very clear about the C callbacks:
https://dlang.org/spec/interfaceToC.html#callbacks
C code:
typedef bool (*onProcessCallback)(const short*, size_t, void*);
D Code:
-
class Game
{
onProcessCallback m_onProcessCb;
this()
{
m_onProcessCb = // Error here
}
void onProcess()
{
// ...
}
extern(C) bool onProcessCb(const short* a, size_t b, void* c)
{
onProcess();
return true;
}
}
private extern(C)
{
// Should call onProcess() when executed by the C lib
alias onProcessCallback = bool function(const short*, size_t,
void*);
}
-
This is because onProcessCb is a member of an object. Therefore,
it carries also the information about the context, which includes
e.g. all members of the class.
Due to this onProcessCb is a delegate, which is something
different from a function, cf.
https://dlang.org/spec/function.html#closures
So, there is a type mismatch.
Re: Dynamic Arrays as Stack and/or Queue
On Monday, 7 October 2019 at 19:38:50 UTC, mipri wrote: On Monday, 7 October 2019 at 19:16:31 UTC, IGotD- wrote: On Monday, 7 October 2019 at 17:36:09 UTC, Ferhat Kurtulmuş wrote: I'm not talking about memory deletion. I'm talking about push, pop, enqueue, and dequeue behavior. I'd assume in a garbage collected language letting the reference float off should be picked up by the GC. I'm sorry. Writing on my mobile phone. Maybe this is what you are looking for https://dlang.org/phobos/std_container_dlist.html I think what he is looking for are the general pop_front, push_front, pop_back and push_back that you would find in virtually any C++ STL container algorithms like list, vector or map. I think this is a good question as I don't really see any good example in the documentation of the dynamic arrays about this. This is very common use case for arrays. Is there any D equivalent? With the performance that you'd expect, I believe: #! /usr/bin/env rdmd [...] I assume this is a little bit more complicated: while popFront and popBack are ubiquitous in ranges in D, the push functions can't be unified in terms of memory management. For example, you cannot guarantee any performance, while using GC. This opposed to complexity, which is, of course, known. Maybe, this is the reason, why such containers are omitted in Phobos (?) But: There is a priority queue, named binaryheap: https://dlang.org/phobos/std_container_binaryheap.html and there are hints, that for a stack you have to rely e.g., on an array or a list implementation http://www.cplusplus.com/reference/stack/stack/ both exist in phobos: https://dlang.org/phobos/std_container_array.html https://dlang.org/phobos/std_container_dlist.html This gives rise to user implementations like https://code.dlang.org/packages/queue https://code.dlang.org/packages/mergearray etc. Maybe, there will be more soon? ;)
Re: how to determine if a function exists in a class?
On Wednesday, 2 October 2019 at 06:06:20 UTC, TodNaz wrote: Hello everyone! I have a question: how to determine if a function exists in a class? Is this possible with @pointer tagging? Do you mean, like in examples of https://dlang.org/library/std/traits/has_member.html ?
Re: Looking for a Simple Doubly Linked List Implementation
On Friday, 20 September 2019 at 20:26:03 UTC, Ron Tarrant wrote: Hi guys, I've been banging my head on the screen with this one for the last week or so. For whatever reason, I'm having major problems understanding how to implement a doubly-linked list in D. I don't know if it's because I'm losing my ability to sort these things or if it's just that different from C. If someone could please post a minimal example (if there's extra stuff in there, I'll get confused; I'm getting that old, dammit) I'd be ever so grateful. rosetta code is quite good for such problems http://rosettacode.org/wiki/Doubly-linked_list/Definition#D
Re: need this for name of type string
On Tuesday, 10 September 2019 at 10:32:29 UTC, Andre Pany wrote:
Hi,
following coding is throwing compiler error:
need this for name of type string
The error disappears if I delete method0.
My gut feeling is, this is a compiler bug?
---
class C
{
static this()
{
getT!(typeof(this))();
}
@Foo void method0(){}
@Foo("abc") void method1(){}
}
struct Foo
{
string name;
}
void getT(T)()
{
import std.traits: hasUDA, getUDAs;
static foreach(fieldName; __traits(allMembers, T))
{
static if (hasUDA!(__traits(getMember, T, fieldName),
Foo))
{
pragma(msg, getUDAs!(__traits(getMember, T,
fieldName), Foo)[0].name);
}
}
}
void main(){}
---
Kind regards
André
Don't think so. In case of @Foo, you don't instantiate an object.
Therefore, name cannot exist. So... in this case, the UDA is a
type, not an object you can query for a name.
It's more the like the example with SimpleAttr on the help page
[1], I think.
[1] https://dlang.org/library/std/traits/get_ud_as.html
Re: What the abstrac final class mean?
On Monday, 12 August 2019 at 08:54:56 UTC, lili wrote: Hi: Why need defined an abstract final class? see https://github.com/Rikarin/Trinix/blob/master/Kernel/arch/amd64/gdt.d From what I saw, all members are static. So, this is a kind of utility class, which is not supposed to be instantiated, nor to be derived from. Maybe, it serves like a namespace, for convenience...
Re: Abstract classes vs interfaces, casting from void*
On Sunday, 11 August 2019 at 20:32:14 UTC, John Colvin wrote: As I see this, everything you wrote is correct. :) But you compared abstractness with interface usage, initially. So... I would say, interfaces are more like the abstract method case without any function body. But then, you will have to use "override" all across the inherited classes. Ok. So that means the difference is pretty subtle, give or take a few extra keywords. Which leaves multiple inheritance as the only significant difference? From my perspective it looks like there are two massively overlapping features with some quite arbitrary feeling restrictions and differences. E.g. why can I not inherit from multiple 100% abstract empty classes? Wouldn't that be the same as inheriting from multiple interfaces? The overlap is there, but it is not so massive, I would say. If you inherit from abstract classes, then you do not plan to keep them empty. So, the overlap you are speaking about is exactly as large as the amount of "100% abstract empty classes". And for these, the approach to keep the interface as a separate interface seems more convenient, as Adam said. In the end, by forcing an explicit override, some semantic is also implied.
Re: Abstract classes vs interfaces, casting from void*
On Sunday, 11 August 2019 at 16:05:20 UTC, John Colvin wrote:
I'm trying to narrow down exactly what patterns work with each
and how they overlap.
What I was trying to get at with the abstract method thing is
that
abstract class C
{
void foo();
}
is an abstract class with a non-abstract method, whose
implementation is going to come from somewhere else (not a
common pattern in D).
class C
{
abstract void foo();
}
is an abstract class with an abstract method foo, which means
you have to override it in a inheriting class to get a
non-abstract class.
As I see this, everything you wrote is correct. :)
But you compared abstractness with interface usage, initially.
So... I would say, interfaces are more like the abstract method
case without any function body. But then, you will have to use
"override" all across the inherited classes.
Re: Abstract classes vs interfaces, casting from void*
On Sunday, 11 August 2019 at 13:09:43 UTC, John Colvin wrote: Ok. What would go wrong (in D) if I just replaced every interface with an abstract class? I think there's some confusion here, because B.foo is not abstract. abstract on a class is not inherited by its methods. https://dlang.org/spec/attribute.html#abstract Now, I'm confused, as you asked about abstract classes. So, yes, you can define the abstractness of classes differently. And what is your point?
Re: Passing nested template function
On Saturday, 10 August 2019 at 17:45:43 UTC, Prateek Nayak wrote: A nested function can be passed to another function evident from this example: https://run.dlang.io/is/6waRkB However if the nested function is a template function, it raises an error https://run.dlang.io/is/PQhkwl The error being: cannot get frame pointer to the nested function Is there a way to pass a nested template function to a function declared outside the outer function scope? The part I'm not sure about: This is not possible: Before instantiation, the object does not exist, you cannot, therefore, pass its pointer, not to speak about the pointer of its frame. However, how about this: https://run.dlang.io/is/8drZRf
Re: Abstract classes vs interfaces, casting from void*
On Saturday, 10 August 2019 at 14:29:03 UTC, John Colvin wrote:
On Saturday, 10 August 2019 at 10:11:15 UTC, Alex wrote:
On Saturday, 10 August 2019 at 08:20:46 UTC, John Colvin wrote:
On Friday, 9 August 2019 at 13:39:53 UTC, Simen Kjærås wrote:
Thanks for the extra detail.
Is there a solid reason to ever use an interface over an
abstract class? (Other than multiple inheritance).
I'm such a noob at anything related to OO.
The general question is tricky, as different languages differ
in details what is forced and what is allowed for abstract
classes and interfaces.
But roughly speaking, my opinion is: if you can/want to
provide some default behavior than you are about to write an
abstract class.
If you are about to provide information/restriction of
behavior, then this is more like an interface.
Ok. What would go wrong (in D) if I just replaced every
interface with an abstract class?
´´´
void main(){}
interface A { void fun(); }
abstract class B{ void fun(); }
class C : A{ void fun(){} }
class D : B{ /*override*/ void fun(){} }
´´´
case 1:
interface A and class C implementing interface A:
You don't need to "override" anything. You are forced to provide
an implementation of the function inside the class.
case 2:
abstract class B and class D inheriting from it:
You can but not have to provide an implementation of a function
inside the abstract class.
If I don't and do not provide any implementation inside D I get a
linker error. Don't how this case behaves on your system.
If you provide an implementation inside the abstract class, you
don't have to provide any in the derived one.
In any case, if you want to provide an implementation inside the
derived class you have to literally "override", as in D implicit
overrides are not allowed.
Re: Abstract classes vs interfaces, casting from void*
On Saturday, 10 August 2019 at 08:20:46 UTC, John Colvin wrote: On Friday, 9 August 2019 at 13:39:53 UTC, Simen Kjærås wrote: Thanks for the extra detail. Is there a solid reason to ever use an interface over an abstract class? (Other than multiple inheritance). I'm such a noob at anything related to OO. The general question is tricky, as different languages differ in details what is forced and what is allowed for abstract classes and interfaces. But roughly speaking, my opinion is: if you can/want to provide some default behavior than you are about to write an abstract class. If you are about to provide information/restriction of behavior, then this is more like an interface.
Re: Is it possible to execute a function inside .d script that has no main function?
On Thursday, 11 July 2019 at 09:43:55 UTC, BoQsc wrote:
Here I have a file named: module.d
import std.stdio : writeln;
void interestingFunction(){
writeln("Testing");
}
There is no main() function since, I want to import this
module, into another .d file.
( If I try to import and module.d does have main() function I
get this error: )
otherFile.d(13): Error: only one main, WinMain, or DllMain
allowed. Previously found main at module.d(3)
I would like to launch function "interestingFunction()"
directly using rdmd.
Is it possible to achieve that by any way?
I tried to launch the whole file, but it gave me some weird
output:
C:\Users\User\Desktop\Environment variables>rdmd module.d
OPTLINK (R) for Win32 Release 8.00.17
Copyright (C) Digital Mars 1989-2013 All rights reserved.
http://www.digitalmars.com/ctg/optlink.html
OPTLINK : Warning 134: No Start Address
If you are trying to test a function separately from other
functions, e.g. for testing, then you are approaching unit
testing.
You could write a unit test block just under the function to test
like
unittest
{
interestingFunction;
}
and launch it via rdmd... don't know the syntax right now. But
here is something:
https://stackoverflow.com/questions/10694994/rdmd-is-not-running-unit-tests
So, I assume something like
rdmd -unittest --main module.d
Re: For loop with separator
On Thursday, 4 July 2019 at 17:00:33 UTC, Q. Schroll wrote:
Probably you've come over this problem once in a while, too.
You have a repeating solution, so you use a for(each) loop.
Sometimes, there is an action to be performed between the end
of one iteration and the beginning of the next, if there is
one. The prime example is printing the comma when printing a
list: There is one between any two elements, but neither is one
at front or behind the last one.
Typical solutions I employed were:
1 Handling the first element separately
2 Condition in the loop, that is false exactly for the first
iteration.
1 can be done with ranges easily:
if (!range.empty)
{
action(range.front);
range.popFront;
foreach (element; range)
{
betweenAction();
action(element);
}
}
This approach is clearly quite verbose for the problem, but
there's nothing done unnecessarily.
2 can be done easily, too:
foreach (i, element; range)
{
if (i > 0) betweenAction();
action(element);
}
While 2 is less code, it's prone to be checked every iteration.
Note that 2 is rather D specific in its length. It can be done
in other languages, but is more verbose.
Is there a cleaner solution that I missed?
As far as I can interpret it, joiner
https://dlang.org/library/std/algorithm/iteration/joiner.html
uses roughly the first approach.
Re: create and initialise array
Thanks Matheus, thats what i needed. I added a PR to mention this function in the language documentation about arrays.
create and initialise array
Is there a way of creating and initialising a dynamic array ? for example I am doing this: auto arr = new float[]; arr[] = 0.0f; Profiling indicates that the compiler (gdc) is spending significant time memsetting the whole array to something (nan ?) before I immediately memset it to 0.0f. It would be good if there was a way of either void initialing it so that the first memset is avoided or a way of replacing the init value with a different one. Thanks, Alex
Re: Delegate / Error: cannot implicitly convert expression...
On Saturday, 15 June 2019 at 16:34:22 UTC, Robert M. Münch wrote:
On 2019-06-15 16:19:23 +, Anonymouse said:
By design, I think: "delegate and function objects cannot be
mixed. But the standard function std.functional.toDelegate
converts a function to a delegate."
Your example compiles if the assignment is changed to dg =
toDelegate(); (given appropriate imports).
https://tour.dlang.org/tour/en/basics/delegates
https://dlang.org/phobos/std_functional.html#.toDelegate
Hmm... but this here compiles:
void main()
{
import std.stdio: write, writeln, writef, writefln;
void foo(int a) {return; }
void test()
{
void delegate(int) dg;
dg =
}
}
See: https://run.dlang.io/is/U7uhAX
Is it because inside main() there is a stack frame? And with a
global function there is none? I'm a bit confused...
Correct. Inside main, foo is a delegate.
https://dlang.org/spec/function.html#nested
Re: Elegant way to test if members of array A are present in array B?
On Tuesday, 11 June 2019 at 17:12:17 UTC, Robert M. Münch wrote: Is there a simple and elegant way to do this? Or is just using a foreach(...) with canFind() the best way? There is also find_among, but the performance is the same, I assume. https://dlang.org/library/std/algorithm/searching/find_among.html
Re: How to create a template class using foreach delegate to filter objects in a member function call?
On Saturday, 1 June 2019 at 14:24:11 UTC, Robert M. Münch wrote:
The myFilter struct is the implementation which myClass.put()
should use to iterate over all objects.
Which ones? The E-objects, or the objects contained in myClass,
which you don't want to know about?
All things being only examples.
Sure. So, please, provide a minimal example, as I'm only guessing
what use case you want to solve. Even if it is not compilable.
So, the idea is, that I can provide a delegate which
foreach(...; myFilter(objects)) uses. Like a run-time plug-in.
Maybe you can. But "put" has to remain a function, not a template.
Do you have control about the contained classes? If so, it is
a hint to implement the testing inside them. Like:
/* probably inside a templated mixin */
bool testfunction(inputs){...}
class myOtherClass(/*probably templated*/){... mixin
testfunction ... & provide a put function}
I thought about a mixin too. But this requires an understanding
of how myClass works. Which I what I want to avoid.
Over which objects your filter will be iterating then?
* So, you are not totally against the idea of modifying the
foreign library, but you want to keep modifications small?
Yes, because myClass is some external lib, which can be changed
to support this approach here. But not more.
Re: How to create a template class using foreach delegate to filter objects in a member function call?
On Friday, 31 May 2019 at 16:24:28 UTC, Robert M. Münch wrote:
The code is just to show the problem and not meant to compile.
I couldn't get anything to compile...
That's ok, but could you provide an example anyway? Is it like
this?
´´´
void main(){
auto target = new myClass!int();
target.objects.length = 4;
auto val = 42;
put(target, val, testfunction); // does the test function
enters here?
put(target, val);
auto f = myFilter!int; // where do you want to use this
entity?
}
´´´
Said this, I for myself had a similar problem. I solved this
by reversing the hierarchy: I templated my objects I wanted to
use the filter on with the filter function and removed the
need of the template parameter inside the filter.
The thing is, myClass is not under my control. It's coming from
a library I don't maintain and I don't want to mess around with
the code or if, as minimalistic as possible. That's why I was
thinking about providing a put(T)... function.
*
My first idea was to sub-class myClass, but objects is private,
so no chance to get access to it.
You could still write a general filter function in this case,
if you want. For example, you could use mixins for this...
Then myClass needs to somehow get the mixin in.
So, to summarize the problem: Given a class that manages an
array of things as an OutputRange how can I provide a put()
function with something like a filter-predicate? I only want to
put() to some of the things, not all.
Do you have control about the contained classes? If so, it is a
hint to implement the testing inside them. Like:
/* probably inside a templated mixin */
bool testfunction(inputs){...}
class myOtherClass(/*probably templated*/){... mixin testfunction
... & provide a put function}
* So, you are not totally against the idea of modifying the
foreign library, but you want to keep modifications small? With
the approach now, you could, for example, handle compile time
blocks inside the put function in the myClass and dynamical ones
inside the myOtherClasses.
class myClass(E){/* inserted put function */ void put(...){static
if put action is at all possible --> put. }}
Re: How to create a template class using foreach delegate to filter objects in a member function call?
On Thursday, 30 May 2019 at 18:34:31 UTC, Robert M. Münch wrote:
I have myClass and I want to add a way where I can provide a
delegate to iterate over myClass.objects when a member function
put(...) of myClass is called. The idea is that a user of
myClass can provide something like an "iterator filter" so that
the function is only called on a subset of myClass.objects.
myClass(E){
myOtherClass!E objects;
void put(E obj) {
.put(objects, obj);
}
void put(T)(E obj, T filter) {
foreach(o ; filter!E(objects)){
.put(o, obj);
}
}
}
struct myFilter {
myOtherClass!E object;
opApply(int delegate(E) foreach_body) const {
if(mytestfunc(object))
return(foreach_body(object));
}
}
But I'm struggeling how to write all this down with tempaltes,
because E is not known in myFilter. But the filter code needs
to be aware of the template type if myClass. I hope the idea
want to do is understandable.
Not sure, if I understood your problem correctly. It is meant
that the class myClass defines an array of myOtherClass objects?
The code does not compile and it does not provide an example, how
you would apply the pattern, even in a non-compileable way...
However,
commonly, a filter is a higher order function, which expects a
predicate acting on each element of a set. Even if it's higher
order, it is still a function, not a delegate. Therefore, it is
unexpected, that you want to store something inside the filter.
Said this, I for myself had a similar problem. I solved this by
reversing the hierarchy:
I templated my objects I wanted to use the filter on with the
filter function and removed the need of the template parameter
inside the filter.
You could still write a general filter function in this case, if
you want. For example, you could use mixins for this...
As I said... not sure if this is of any help for you...
Re: Performance of tables slower than built in?
On Friday, 24 May 2019 at 13:57:30 UTC, Ola Fosheim Grøstad wrote: On Friday, 24 May 2019 at 12:24:02 UTC, Alex wrote: If it truly is a 27x faster then then that is very relevant and knowing why is important. Of course, a lot of that might simply be due to LDC and I wasn't able to determine this. Just one more thing you really ought to consider: It isn't obvious that a LUT using double will be more precise than computing sin using single precision float. So when I use single precision float with ldc and "-O3 -ffast-math" then I get roughly 300ms. So in that case the LUT is only 3 times faster. Perhaps not worth it then. You might as well just use float instead of double. The downside is that -ffast-math makes all your computations more inaccurate. It is also possible that recent processors can do multiple sin/cos as simd. Too many options… I know. The thing is, the LUT can have as much precision as one wants. One could even spend several days calculating it then loading it from disk. I'm not sure what the real precision of the build in functions are but it shouldn't be hard to max out a double using standard methods(even if slow, but irrelevant after the LUT has been created). Right now I'm just using the built ins... Maybe later I'll get back around to all this and make some progress.
Re: Performance of tables slower than built in?
On Friday, 24 May 2019 at 11:45:46 UTC, Ola Fosheim Grøstad wrote:
On Friday, 24 May 2019 at 08:33:34 UTC, Ola Fosheim Grøstad
wrote:
On Thursday, 23 May 2019 at 21:47:45 UTC, Alex wrote:
Either way, sin it's still twice as fast. Also, in the code
the sinTab version is missing the writeln so it would have
been faster.. so it is not being optimized out.
Well, when I run this modified version:
https://gist.github.com/run-dlang/9f29a83b7b6754da98993063029ef93c
on https://run.dlang.io/
then I get:
LUT:709
sin(x): 2761
So the LUT is 3-4 times faster even with your quarter-LUT
overhead.
FWIW, as far as I can tell I managed to get the lookup version
down to 104 by using bit manipulation tricks like these:
auto fastQuarterLookup(double x){
const ulong mantissa = cast(ulong)( (x - floor(x)) *
(cast(double)(1UL<<63)*2.0) );
const double sign =
cast(double)(-cast(uint)((mantissa>>63)&1));
… etc
So it seems like a quarter-wave LUT is 27 times faster than sin…
If so then that is great and what I'd expected to achieve
originally.
I guess this is using LDC though? I wasn't able to compile with
LDC since after updating I'm getting linker errors that I have to
go figure out.
You just have to make sure that the generated instructions
fills the entire CPU pipeline.
What exactly does this mean? I realize the pipeline in cpu's is
how the cpu decodes and optimizes the instructions but when you
say "You have to make sure" that pre-supposes there is a method
or algorithm to know.
Are you saying that I did not have enough instructions that the
pipeline could take advantage of?
In any case, I'll check your code out and try to figure out the
details and see exactly what is going on.
If it truly is a 27x faster then then that is very relevant and
knowing why is important.
Of course, a lot of that might simply be due to LDC and I wasn't
able to determine this.
Can you do some stats for dmd and ldc?
You seem to be interested in this, are you up for a challenge?
The idea is to use tables to optimize these functions.
Half sin was done above but quarter sine can be used(there are 4
quadrants but only one has to be tabularized because all the
others differ by sign and reversion(1 - x), it's a matter of
figuring out the sign).
Of course it requires extra computation so it would be
interesting to see the difference in performance for the extra
logic.
Then there is exp
exp(x) can be written as exp(floor(x) + {x}) =
exp(floor(x))*exp({x})
and so one can optimize this by tabulating exp(x) for 0<= x < 1
which is the fractional part of exp(x).
Then tabulating it for a wide range of integers(probably in 2's).
e.g.,
exp(3.5) = exp(3)*exp(.5)
both come from a lookup table.
or one could do
exp(3) = exp(1 + 1 + 1) = exp(1)*exp(1)*exp(1)
(this requires iteration if we do not tabulate exp(3).
Hence one would limit the iteration count by tabulating things
like exp(10^k) and exp(k) for -10 < k < 10.
The idea is basically one can get really dense LUT's for a small
range that then are used to build the function for arbitrary
inputs.
With linear interpolation one can get very accurate(for all
practical purposes) LUT table methods that, if your code is
right, is at least an order of magnitude faster. The memory
requirements will be quite small with linear interpolation(and
ideally quadratic or cubic if the costs are not too high).
That was what I was starting to work on before I got thrown off
by it being much slower.
It seems you already have the half-sin done.
One could do things like sin, cos(obviously easy), exp, exp()^2,
erf(x), sinh, cosh, etc. Things like sec could also be done as it
would save a division since it seems they take about 30 cycles.
But it would depend on the memory used.
[I can't mess with this now because I've gotta work other things
at the moment]
Thanks.
Re: Performance of tables slower than built in?
On Friday, 24 May 2019 at 11:57:44 UTC, Alex wrote:
On Friday, 24 May 2019 at 08:13:00 UTC, Basilez B. wrote:
On Thursday, 23 May 2019 at 10:16:42 UTC, Alex wrote:
On Wednesday, 22 May 2019 at 08:25:58 UTC, Basile B. wrote:
On Wednesday, 22 May 2019 at 00:22:09 UTC, JS wrote:
I am trying to create some fast sin, sinc, and exponential
routines to speed up some code by using tables... but it
seems it's slower than the function itself?!?
[...]
Hi, lookup tables ARE faster but the problem you have here,
and I'm surprised that nobody noticed it so far, is that
YOUR SWITCH LEADS TO A RUNTIME STRING COMPARISON AT RUNTIME.
Just replace it with a static if (Method = "Linear") {
/*...*/} else { /*...*/}
Also takes care to the type used. With DMD the implicit
coercion of float and double can lead to extra conversions.
You'll directly see a 15% gain after refactoring the switch.
Surely not?!?! Surely the compiler can optimize that switch
since the value passed is CT? I thought the whole point of
not having static switch(analogous to static if) was because
it would go ahead and optimize these cases for us... and it's
just a switch, just a jmp table.
Try by yourself but to be clear note that I don't like your
attitude, which I find disrespectful.
Are you an idiot or on medications? My attitude? What did you
want me to do? Suck your cock? My attitude? Seriously? WHERE?
WHERE? You quoted everything?
I don't like your attitude? You seem to be extremely
oversensitive and take things out of context?
It sounds like you just don't like people questioning you in
any way shape or form even if you are wrong.
"Surely not?!?! Surely the compiler can optimize that switch
since the value passed is CT? I thought the whole point of not
having static switch(analogous to static if) was because it
would go ahead and optimize these cases for us... and it's
just a switch, just a jmp table."
Where? I seriously do not like your attitude though! You attack
me when I said nothing offensive to you. You have serious
problems. Get back on or get off the lithium.
[Now, of course, you get to see what an attitude really looks
like... maybe I've taught you a bit about perspective? I doubt
it.]
What amazes me is that you Basilez come in and start stuff and
yet my response to you starting stuff will get deleted and yours
won't... that is typical.
You really have mental issues. No where in my post was I hostile
to you and yet you decided to have a hissy fit. You are a
snowflake that obviously need a ass kicking. That will teach you
not to be so sensitive and interpret things in your own little
cushioned wall universe.
See, no one was attacking you or questioning your intelligence...
that is something you perceived and made up all on your own. But
you will be supported by all the other people who love cushy
walls and koolaid rather than getting the help you need.
Re: Performance of tables slower than built in?
On Friday, 24 May 2019 at 11:45:46 UTC, Ola Fosheim Grøstad wrote:
On Friday, 24 May 2019 at 08:33:34 UTC, Ola Fosheim Grøstad
wrote:
On Thursday, 23 May 2019 at 21:47:45 UTC, Alex wrote:
Either way, sin it's still twice as fast. Also, in the code
the sinTab version is missing the writeln so it would have
been faster.. so it is not being optimized out.
Well, when I run this modified version:
https://gist.github.com/run-dlang/9f29a83b7b6754da98993063029ef93c
on https://run.dlang.io/
then I get:
LUT:709
sin(x): 2761
So the LUT is 3-4 times faster even with your quarter-LUT
overhead.
FWIW, as far as I can tell I managed to get the lookup version
down to 104 by using bit manipulation tricks like these:
auto fastQuarterLookup(double x){
const ulong mantissa = cast(ulong)( (x - floor(x)) *
(cast(double)(1UL<<63)*2.0) );
const double sign =
cast(double)(-cast(uint)((mantissa>>63)&1));
… etc
So it seems like a quarter-wave LUT is 27 times faster than sin…
You just have to make sure that the generated instructions
fills the entire CPU pipeline.
Well, the QuarterWave was suppose to generate just a quarter
since that is all that is required for these functions due to
symmetry and periodicity. I started with a half to get that
working then figure out the sign flipping.
Essentially one just has to tabulate a quarter of sin, that is,
from 0 to 90o and then get the sin right. This allows one to have
4 times the resolution or 1/4 the size at the same cost.
Or, to put it another say, sin as 4 fold redundancy.
I'll check out your code, thanks for looking in to it.
Re: Performance of tables slower than built in?
On Friday, 24 May 2019 at 08:13:00 UTC, Basilez B. wrote:
On Thursday, 23 May 2019 at 10:16:42 UTC, Alex wrote:
On Wednesday, 22 May 2019 at 08:25:58 UTC, Basile B. wrote:
On Wednesday, 22 May 2019 at 00:22:09 UTC, JS wrote:
I am trying to create some fast sin, sinc, and exponential
routines to speed up some code by using tables... but it
seems it's slower than the function itself?!?
[...]
Hi, lookup tables ARE faster but the problem you have here,
and I'm surprised that nobody noticed it so far, is that YOUR
SWITCH LEADS TO A RUNTIME STRING COMPARISON AT RUNTIME. Just
replace it with a static if (Method = "Linear") { /*...*/}
else { /*...*/}
Also takes care to the type used. With DMD the implicit
coercion of float and double can lead to extra conversions.
You'll directly see a 15% gain after refactoring the switch.
Surely not?!?! Surely the compiler can optimize that switch
since the value passed is CT? I thought the whole point of not
having static switch(analogous to static if) was because it
would go ahead and optimize these cases for us... and it's
just a switch, just a jmp table.
Try by yourself but to be clear note that I don't like your
attitude, which I find disrespectful.
Are you an idiot or on medications? My attitude? What did you
want me to do? Suck your cock? My attitude? Seriously? WHERE?
WHERE? You quoted everything?
I don't like your attitude? You seem to be extremely
oversensitive and take things out of context?
It sounds like you just don't like people questioning you in any
way shape or form even if you are wrong.
"Surely not?!?! Surely the compiler can optimize that switch
since the value passed is CT? I thought the whole point of not
having static switch(analogous to static if) was because it
would go ahead and optimize these cases for us... and it's
just a switch, just a jmp table."
Where? I seriously do not like your attitude though! You attack
me when I said nothing offensive to you. You have serious
problems. Get back on or get off the lithium.
[Now, of course, you get to see what an attitude really looks
like... maybe I've taught you a bit about perspective? I doubt
it.]
Re: Performance of tables slower than built in?
On Thursday, 23 May 2019 at 18:57:03 UTC, Ola Fosheim Grøstad wrote: On Wednesday, 22 May 2019 at 00:22:09 UTC, JS wrote: I am trying to create some fast sin, sinc, and exponential routines to speed up some code by using tables... but it seems it's slower than the function itself?!? Not when I tried it with one of the online compilers, LUT is 3-4 times faster on your tight inner loop, but I guess it depends on the CPU. LUT should be very fast in long-running tight inner loops like that once the cache is warm with such as small LUT that fits in working memory (cache). I've used very small LUT's like a length of 5 and it didn't significantly change anything. Unless it is being hit hard at the start and that is skewing the results, it doesn't seem to be the issue. I haven't tested this well but was just thrown off by the results as it should easily have been inverted and I expected quite a significant speed up(several factors) and not the reverse.
Re: Performance of tables slower than built in?
On Thursday, 23 May 2019 at 19:17:40 UTC, Ola Fosheim Grøstad wrote: On Wednesday, 22 May 2019 at 00:22:09 UTC, JS wrote: xxx = 0; sw.reset(); sw.start(); for(double i = 0; i < 1000; i++) xxx += sin(PI*i); t = sw.peek().msecs; writeln(t); sw.stop(); } What you are doing wrong is that xxx is never used... So DMD removes it altogether? If you add writeln(xxx) after the second loop as well, then maybe the measurements make more sense? Ola. maybe, I thought I put in the writeln(xxx) in there to do that... yeah, looking at my code it's there, so that is not the problem. This is the code I had, import std.datetime; double xxx = 0; StopWatch sw; sw.start(); for(double i = 0; i < 1000; i++) xxx += sinTab(i); auto t = sw.peek().msecs; writeln(t); sw.stop(); writeln(xxx); xxx = 0; sw.reset(); sw.start(); for(double i = 0; i < 1000; i++) xxx += sin(PI*i); t = sw.peek().msecs; writeln(t); sw.stop(); writeln(xxx); Either I modified it later or deleted one of those lines or the editor screwed up when I pasted it... I don't recall touching the code afterwards. Either way, sin it's still twice as fast. Also, in the code the sinTab version is missing the writeln so it would have been faster.. so it is not being optimized out.
Re: Performance of tables slower than built in?
On Thursday, 23 May 2019 at 15:20:22 UTC, Timon Gehr wrote: On 23.05.19 12:21, Alex wrote: On Wednesday, 22 May 2019 at 00:55:37 UTC, Adam D. Ruppe wrote: On Wednesday, 22 May 2019 at 00:22:09 UTC, JS wrote: I am trying to create some fast sin, sinc, and exponential routines to speed up some code by using tables... but it seems it's slower than the function itself?!? There's intrinsic cpu instructions for some of those that can do the math faster than waiting on memory access. It is quite likely calculating it is actually faster. Even carefully written and optimized tables tend to just have a very small win relative to the cpu nowadays. Surely not? I'm not sure what method is used to calculate them and maybe a table method is used internally for the common functions(maybe the periodic ones) but memory access surely is faster than multiplying doubles? ... Depends on what kind of memory access, and what kind of faster. If you hit L1 cache then a memory access might be (barely) faster than a single double multiplication. (But modern hardware usually can do multiple double multiplies in parallel, and presumably also multiple memory reads, using SIMD and/or instruction-level parallelism.) I think a single in-register double multiplication will be roughly 25 times faster than an access to main memory. Each access to main memory will pull an entire cache line from main memory to the cache, so if you have good locality (you usually won't with a LUT), your memory accesses will be faster on average. There are a lot of other microarchitectural details that can matter quite a lot for performance. I realize a lot of optimizations could be made but I still find it hard to believe that it could be done faster even with special hardware unless a LUT is used in the hardware already or some highly optimized algorithms. The whole point of general purpose computing was to get away from specialized hardware because it was cheaper and one could spend the resources in improving raw cycle performance which would benefit the entire system. But I guess because of complexity of hardware now days it's hard to really figure out what is going on. http://ithare.com/infographics-operation-costs-in-cpu-clock-cycles/ Maybe when it is an "intrinsic" it can avoid some of the issues that might otherwise cost in a LUT(such as a context switch). And most of the time these functions are computed by some series that requires many terms. I'd expect, say, to compute sin one would require at least 10 multiplies for any accuracy... and surely that is much slower than simply accessing a table(it's true that my code is more complex due to the modulos and maybe that is eating up the diff). Do you have any proof of your claims? Like a paper that discusses such things so I can see what's really going on and how they achieve such performance(and how accurate)? Not exactly what you asked, but this might help: https://www.agner.org/optimize Also, look up the CORDIC algorithm. I don't see how that can necessarily be faster. A LUT can give full 64-bit precision with one operation. The CORDIC needs iteration, at least 10 to be of any use. LUT's are precision independent assuming the creation cost is not included. I couldn't find anything in that link that specifically addressed speeding up typical math functions. It would be nice to know exactly what is going on, which functions are optimized and the typical speed up over a lut. I have some code that uses sin, exp and a few other primitive algebraic functions and in one case the code is extremely slow(it uses exp). I haven't done much testing of all this but something just seems off somewhere. Either the sin is heavily optimized and exp is not(which it too have a CORDIC like algorithm since exp(a+b) = exp(a)*exp(b)) or something else is happening that I'm not aware of.. which is why I went to tabularizing these functions in the first place. Also, I don't know the kinda accuracy they have, which doesn't help much but I could use a more accurate algorithm which is slower since it is pre-computed. That site I linked does talk about some of the issues and stuff... I guess I just need to update my thinking on modern cpus a little better. I guess there is no tool that can tell one exactly what is happening to a piece of code in the cpu... basically an instruction level profiler?
Re: Performance of tables slower than built in?
On Wednesday, 22 May 2019 at 00:55:37 UTC, Adam D. Ruppe wrote: On Wednesday, 22 May 2019 at 00:22:09 UTC, JS wrote: I am trying to create some fast sin, sinc, and exponential routines to speed up some code by using tables... but it seems it's slower than the function itself?!? There's intrinsic cpu instructions for some of those that can do the math faster than waiting on memory access. It is quite likely calculating it is actually faster. Even carefully written and optimized tables tend to just have a very small win relative to the cpu nowadays. Surely not? I'm not sure what method is used to calculate them and maybe a table method is used internally for the common functions(maybe the periodic ones) but memory access surely is faster than multiplying doubles? And most of the time these functions are computed by some series that requires many terms. I'd expect, say, to compute sin one would require at least 10 multiplies for any accuracy... and surely that is much slower than simply accessing a table(it's true that my code is more complex due to the modulos and maybe that is eating up the diff). Do you have any proof of your claims? Like a paper that discusses such things so I can see what's really going on and how they achieve such performance(and how accurate)?
Re: Performance of tables slower than built in?
On Wednesday, 22 May 2019 at 08:25:58 UTC, Basile B. wrote:
On Wednesday, 22 May 2019 at 00:22:09 UTC, JS wrote:
I am trying to create some fast sin, sinc, and exponential
routines to speed up some code by using tables... but it seems
it's slower than the function itself?!?
[...]
Hi, lookup tables ARE faster but the problem you have here, and
I'm surprised that nobody noticed it so far, is that YOUR
SWITCH LEADS TO A RUNTIME STRING COMPARISON AT RUNTIME. Just
replace it with a static if (Method = "Linear") { /*...*/} else
{ /*...*/}
Also takes care to the type used. With DMD the implicit
coercion of float and double can lead to extra conversions.
You'll directly see a 15% gain after refactoring the switch.
Surely not?!?! Surely the compiler can optimize that switch since
the value passed is CT? I thought the whole point of not having
static switch(analogous to static if) was because it would go
ahead and optimize these cases for us... and it's just a switch,
just a jmp table.
Re: Why function does not work with delegate
On Wednesday, 22 May 2019 at 23:54:47 UTC, Adam D. Ruppe wrote:
On Wednesday, 22 May 2019 at 22:33:52 UTC, Alex wrote:
auto x = (GdkEventButton* e, Widget w) ...
X.addOnButtonPress(x);
Why is x not a delegate?
Because you didn't ask for one and it didn't have to be.
Just add the delegate keyword to ask for one:
auto x = delegate(GdkEventButton* e, Widget w) {};
That is what I was looking for.
Thanks.
Why function does not work with delegate
In gtkD one can use a lambda directly:
X.addOnButtonPress((GdkEventButton* e, Widget w) ...
but if I try move the lambda in to a variable so I can use it
with multiple handlers, I get an error:
// x is a function and does not work
auto x = (GdkEventButton* e, Widget w) ...
X.addOnButtonPress(x);
etc...
It's because the second case treats x as a function while the
first it is a delegate and addOnButtonPress requires a delegate...
Why is x not a delegate?
Now, if I reference a variable outside the scope of the lambda it
turns magically in to a delegate and works!
But that is an ugly hack!
// now x is a delegate and works
auto x = (GdkEventButton* e, Widget w) { auto q = X; ...
Now sure I can hack x and use some template to turn it in to a
fake delegate but then that is dangerous.
I suppose one could have a template that only converts it if it
is a function and then that will deal with both cases and might
work...
But why?
Is there any way to force it to not reduce the delegate to a
function which is obviously an optimization when nothing accesses
the outside context.
Re: release build with debug information?
On Tuesday, 21 May 2019 at 09:48:34 UTC, Robert M. Münch wrote: Is it possible to compile a release build with debug information? There is a "release-debug" version in case you are using dub. Not sure, if there is enough debug info for you.
Impose structure on array
given some array, is there some way to easily impose structure on that array at runtime? void* data; auto x = cast(byte[A,B,C])data; X is then an AxBxC matrix. I'm having to compute the index myself and it just seems unnecessary. A and B are not known at compile time though. Obviously it should be just as efficient as computing the offset manually. I could probably do this with a struct and override opIndex but I'm wondering what is already out there. If it's slower or consumes more memory than manual it's not worth it(since my code already calcs the index).
Re: Basic Linear Algebra and D's Array Operation
On Sunday, 19 May 2019 at 16:17:17 UTC, Andrew Edwards wrote:
´´´
import std;
void main()
{
int[][] M = [[1,2,3],[1,2,3],[1,2,3]];
M.recursiveMultiplier(4);
writeln(M);
}
void recursiveMultiplier(T, V)(T arr, V val) @nogc
{
static if(isArray!(ElementType!T))
arr.each!(el => el.recursiveMultiplier(val));
else
arr[] = arr[] * val;
}
´´´
Can you do me a favor and extend it to cover the cases where V
is either an array or multidimensional array? The text I'm
using has exercise to implement a bunch of matrix operations so
that would help out a lot.
Not really. For a general matrix-matrix multiplication special
algorithms exist. ndslices use blas for calculation. For
different numeric types, things get involved very fast, not to
speak about special algorithms for special-formed matrices.
And I don't even know, which representation (row/column major)
you expect ;)
The operation itself is, however, a simple one. To implement a
basic version I would cite
http://rosettacode.org/wiki/Matrix_multiplication#D
Re: Basic Linear Algebra and D's Array Operation
On Sunday, 19 May 2019 at 06:34:18 UTC, Andrew Edwards wrote:
Sooo... I'm trying to learn this stuff so that I can fully
grasp the content of Jens Mueller's 2019 DConf talk and its
applications in financial sector (forex and options/futures
trading). Unfortunately, I'm doing so using python but I'd like
to accomplish the same in D. Here goes:
Array (Vector) Algebra
auto V = [1, 2, 3];
auto v = V[] * 4; // v == [4, 8, 12]
Output:
Error: array operation V[] * 4 without destination memory not
allowed
Huh? What? That makes no sense, but okay... whatever.
int[3] v = V[] * 4; // v == [4, 8, 12]
v[] = v[] + v[]; // v == [8, 16, 24]
v[] = v[] / 2; // v == [4, 8, 12]
v[] = v[] - v[]; // v = [0, 0, 0]
so far so good. On to the fun stuff.
Multidimensional Array (Matrix) Algebra
auto M = [[1, 2, 3], [1, 2, 3], [1,2,3]];
int[3][3] m = M[] * 4;
Output:
Error: incompatible types for (M[]) * (4): int[][] and int
Okay, I'm lost on that one. But let's press on.
int[3][3] m = M[] * [[4]];
Output:
Error: cannot implicitly convert expression M[] * [[4]] of
type int[][] to int[]
int[3][3] m = M[] * [[4,4,4], [4,4,4], [4,4,4]];
Output:
Error: cannot implicitly convert expression M[] * [[4, 4, 4],
[4, 4, 4], [4, 4, 4]] of type int[][] to int[]
I'm so confused. Maybe it's the way I'm accessing M?
int[3][3] m = M[][] * 4;
Output:
Error: incompatible types for (M[]) * (4): int[][] and int
And... it begins again!!!
So the question is, how do I pull this off in D using just
builtin arrays and phobos?
Any assistance is appreciated.
Matrix operations are a pain in D. This is due to static arrays
and dynamic arrays are different types and don't mix a priori:
https://dlang.org/spec/arrays.html
Slice operations exist, but they are defined mainly for arrays
and not for arrays of arrays. Some basic operations (like
setting) are possible, but as you see, even multiplication fails.
You could reinvent something like
´´´
import std;
void main()
{
int[][] M = [[1,2,3],[1,2,3],[1,2,3]];
M.recursiveMultiplier(4);
writeln(M);
}
void recursiveMultiplier(T, V)(T arr, V val) @nogc
{
static if(isArray!(ElementType!T))
arr.each!(el => el.recursiveMultiplier(val));
else
arr[] = arr[] * val;
}
´´´
BUT:
As I saw, in the talk, NDarrays are referenced. The common
(widely used and recommended) way to use this functionality in D
is by using mir.ndslices.
http://docs.algorithm.dlang.io/latest/mir_ndslice.html
Thanks,
Andrew
P.S. Why do we still have two sets of documentations ([1],[2])
for the language? Which is the official one and when can we get
rid of the other?
[1] https://dlang.org/library/std/array.html
[2] https://dlang.org/phobos/std_array.html
Re: Creating Anonymous structs
On Saturday, 18 May 2019 at 20:53:50 UTC, Alex wrote: On Saturday, 18 May 2019 at 20:03:14 UTC, Adam D. Ruppe wrote: On Saturday, 18 May 2019 at 15:59:05 UTC, Alex wrote: Structs combine data, I have a use case where I do not want to litter the scope with variables and would like to put them in a struct but the variable will only be used once. This is basically what Phobos's Tuple is. auto x = tuple(value_for_x, value_for_y); http://dpldocs.info/experimental-docs/std.typecons.tuple.html I thought about using them but they are not the same. A tuple cannot have functionality. It's not as general as a struct or class and it doesn't look as nice if the struct is large... and if we were to use a class we don't get to inherit. I suppose one could use delegates but it's still a pain because to setup and ends up being more terse than just going about it the standard way.
Re: Creating Anonymous structs
On Saturday, 18 May 2019 at 20:03:14 UTC, Adam D. Ruppe wrote: On Saturday, 18 May 2019 at 15:59:05 UTC, Alex wrote: Structs combine data, I have a use case where I do not want to litter the scope with variables and would like to put them in a struct but the variable will only be used once. This is basically what Phobos's Tuple is. auto x = tuple(value_for_x, value_for_y); http://dpldocs.info/experimental-docs/std.typecons.tuple.html I thought about using them but they are not the same. A tuple cannot have functionality. It's not as general as a struct or class and it doesn't look as nice if the struct is large... and if we were to use a class we don't get to inherit.
Re: Creating Anonymous structs
Also, I realize one could use Voldemort types, e.g., something
like
auto x = (){ struct X { int x; } return X(); }
but this is so verbose as to not really be any better(although it
does accomplish hiding the struct, I'm not so concerned with
hiding the struct as I am code brevity. I do realize there is
very little extra chars but that isn't the point. I'm asking if
there is a way to accomplish what I'd like to do).
Creating Anonymous structs
Structs combine data, I have a use case where I do not want to
litter the scope with variables and would like to put them in a
struct but the variable will only be used once.
struct X
{
int x;
double y;
}
X x;
Seems redundant to have to do this, rather, it would be nice to do
auto x = struct {
int x;
double y;
};
And this would create the same effect but it would only exist in
one place.
Is there any way to accomplish this without actually defeating
the purpose?
Obviously there is not a huge difference between what is possible
and what I want to achieve. I just feel it would be more sound to
use an anonymous struct.
Re: 1 - 17 ms, 553 ╬╝s, and 1 hnsec
On Friday, 17 May 2019 at 18:02:04 UTC, kdevel wrote: On Thursday, 16 May 2019 at 20:31:23 UTC, Vladimir Panteleev wrote: On Thursday, 16 May 2019 at 20:17:37 UTC, Steven Schveighoffer [...] hnsecs is more confusing than nanoseconds. People know what a nanosecond is, a hecto-nano-second is not as familiar a term. Agreed, which is why Duration.toString shouldn't be used to present durations to users. Developers, however, are expected to know what a hectonanosecond is, same as with all the other technical terms. "hectonanosecond" looks like an illegal combination of SI prefixes [1]. I recommend changing the meaning of hnsecs to "[one] hundred nanoseconds". [1] "Prefixes may not be used in combination." https://en.wikipedia.org/wiki/Metric_prefix It through me off, it really makes no sense. The purpose of a prefix is to define something better. hectonano seems contradictory... and is it any different than nanohecto? There really is no point in it, the whole reason for the metric system is to provide a hierarchical resolution. Just use nano or pico
Re: Blog Post #0036 - File Dialog - Open a Single File
On Friday, 17 May 2019 at 09:24:59 UTC, Ron Tarrant wrote: The second post this week continues the series on Dialogs. This one is about opening files and can be found here: http://gtkdcoding.com/2019/05/17/0036-file-open-dialogs.html So, I'm using gtkD and eventually I'll have the need to use movable icons that can be interacted with using the icon by dragging them around in a DrawingArea. So if you need ideas to for another tutorial that would be helpful to me. It's probably not too hard but I've not messed with those things yet and maybe you'll find an easier way to deal with it. The idea would be to create DrawingArea and then display the "icons" and have mouse interaction. I'm not sure if using custom drawing or something built in is best. Custom drawing is probably what I'll do since I know more about that then gtk.
Re: disabling and enabling console output
On Thursday, 16 May 2019 at 17:49:24 UTC, Adam D. Ruppe wrote: On Thursday, 16 May 2019 at 14:53:14 UTC, Alex wrote: I have some code that disables the console because some other code puts junk on it that I don't want to see s stupid question but can't you just edit the other code to not put junk on it? No, it is in an external lib and I'd have to mod the code, maintain it, and compile it... should be much simpler just to redirect stdout. In fact, it works, I just can figure out how to re-enable it.
Re: disabling and enabling console output
On Thursday, 16 May 2019 at 17:19:13 UTC, Vladimir Panteleev wrote: On Thursday, 16 May 2019 at 17:18:01 UTC, Alex wrote: adding int dup(int) @trusted; int dup2(int, int) @trusted; int close(int) @trusted; int open(in char*, int, ...) @trusted; Be sure to make them extern(C). Sorry, I haven't tried it, I'm guessing that it should work based on: https://github.com/digitalmars/dmc/blob/master/include/io.h#L142-L147 Ok, the issue is because I was adding import core.stdc.stdio, core.stdc.stdio; extern (C): @system: nothrow: @nogc: static int _dup(int); static int dup2(int, int); directly inside the PushFD struct... I marked them static and it still didn't help. I don't know it's adding the class for the lookup: PushFD!(1).PushFD.dup2(int, int)" (_D3mM__T6PushFDVii1ZQm4dup2UNbNiiiZi) Unfortunately the code is crashing because _open or _sopen is returning -1 for /dev/null Works fine nul, NUL, and CONOUT$ but does not block the output. I'm not sure if they are failing to block or if they are blocking what is being opened(and not the original console). That is, do I need to not open and simply close stdout?
Re: disabling and enabling console output
On Thursday, 16 May 2019 at 17:07:39 UTC, Vladimir Panteleev wrote: On Thursday, 16 May 2019 at 17:05:01 UTC, Alex wrote: One thing you could try is going one level lower, and using dup() to save the stream to another fd, close() to close the stdout one, and dup2() to restore the saved fd over the stdout one. Unfortunately D doesn't seem to have dup, dup2. They are in the C library. Looks like Druntime has D declarations only for Posix: https://github.com/cybershadow/druntime/blob/issue19433/src/core/sys/posix/unistd.d#L51-L52 You can just copy those. adding int dup(int) @trusted; int dup2(int, int) @trusted; int close(int) @trusted; int open(in char*, int, ...) @trusted; results in an unresolved symbol.
Re: disabling and enabling console output
On Thursday, 16 May 2019 at 15:21:48 UTC, Vladimir Panteleev
wrote:
On Thursday, 16 May 2019 at 14:53:14 UTC, Alex wrote:
I have some code that disables the console because some other
code puts junk on it that I don't want to see... then I enable
it.
One thing you could try is going one level lower, and using
dup() to save the stream to another fd, close() to close the
stdout one, and dup2() to restore the saved fd over the stdout
one.
Unfortunately D doesn't seem to have dup, dup2.
On 05/10/14 22:24, MarisaLovesUsAll via Digitalmars-d-learn wrote:
I sometimes got a useless messages in stdout from SDL_Image
library, and I want to temporary silence it. How do I do?
One way would be something like:
import std.stdio;
void writeOutput () {
static c = 1;
printf("%d\n", c++);
}
void main() {
writeOutput();
{
auto ex = PushFD!1("/dev/null".ptr);
writeOutput();
}
writeOutput();
}
struct PushFD(int fd) {
import core.sys.posix.fcntl, core.sys.posix.unistd;
int old;
this(const char* fn) { //
old = dup(fd);
auto nfd = open(fn, O_RDWR);
dup2(nfd, fd);
close(nfd);
}
~this() { dup2(old, fd); close(old); }
}
// In real code you'll want to check for errors from
dup/dup2/open/close.
artur
That code fails to compile on windows.
Re: 1 - 17 ms, 553 ╬╝s, and 1 hnsec
On Thursday, 16 May 2019 at 15:27:33 UTC, Vladimir Panteleev wrote: On Thursday, 16 May 2019 at 15:19:03 UTC, Alex wrote: 1 - 17 ms, 553 ╬╝s, and 1 hnsec WTH!! is there any way to just get a normal u rather than some fancy useless asci hieroglyphic? Why don't we have a fancy M? and an h? It's outputting UTF-8, but, your console is not configured to display UTF-8. On Windows, you can do so (before running your program), by running: chcp 65001 Or, within your program, by calling: SetConsoleOutputCP(CP_UTF8); Note that this has some negative side effects, which is why D doesn't do it automatically. (Blame Windows.) What's an hnsec anyways? Hecto-nano-second, the smallest representable unit of time in SysTime and Duration. Thanks... Why not just use u? If that is too much trouble then detect the code page and use u rather than the extended ascii which looks very out of place?
1 - 17 ms, 553 ╬╝s, and 1 hnsec
1 - 17 ms, 553 ╬╝s, and 1 hnsec WTH!! is there any way to just get a normal u rather than some fancy useless asci hieroglyphic? Why don't we have a fancy M? and an h? What's an hnsec anyways?
disabling and enabling console output
I have some code that disables the console because some other
code puts junk on it that I don't want to see... then I enable it.
stdout.close();
stderr.close();
...
stdout.open("CON", "w");
stderr.open("CON", "w");
It works but when the routine that uses this is called twice, it
completely disables all output afterwards.
//1
stdout.close();
stderr.close();
//2
stdout.open("CON", "w");
stderr.open("CON", "w");
//3
stdout.close();
stderr.close();
//4
stdout.open("CON", "w");
stderr.open("CON", "w");
//5
So, one gets output at 1 and 3 but not 5.
Am I doing something wrong or is this a bug?
I've tried various things such as saving and restoring stdout,
using CONOUT$, etc...
I think it might be outputting in 3 because of caching rather
than it actually working once.
Can play around with it here:
https://run.dlang.io/is/q3kpSB
Re: GtkD slows down visual D keyboard
A hack:
On Tue, 14 May 2019 19:44:01 +0200, Mike Wey wrote:
On 14-05-2019 05:10, Alex X wrote:
Any news on this?
https://forum.dlang.org/thread/bznpylcjostbrrwzh...@forum.dlang.org
It's severely cramping my style ;/
Unfortunately no.
// The following code bypasses GTK windows hooking that causes
problems with visual studio debugging(slow keyboard, it is a hack
and may not work in general)
debug {
import core.sys.windows.windows, core.stdc.string;
alias HHOOK function(int, HOOKPROC, HINSTANCE, DWORD)
SetWindowsHookExAProc;
alias HHOOK function(int, HOOKPROC, HINSTANCE, DWORD)
SetWindowsHookExWProc;
static extern (Windows) HHOOK KBHook(int, HOOKPROC, HINSTANCE,
DWORD)
{
asm
{
naked;
ret;
}
}
DWORD old;
auto err = GetLastError();
auto hModule = LoadLibrary("User32.dll");
auto proc = cast(SetWindowsHookExAProc)GetProcAddress(hModule,
"SetWindowsHookExA");
err = GetLastError();
VirtualProtect(proc, 40, PAGE_EXECUTE_READWRITE, );
err = GetLastError();
memcpy(proc, , 7);
// Cleanup
//FreeLibrary(hModule);
}
The code above is based on the idea from
https://github.com/microsoft/Detours
I didn't feel like investing the time to integrate it in to my
code.
The code I've included is a hack that simply bypasses all hooking
routines and hence the screwed up keyboard hook.
It only works for x64 since ret works to return properly(x86
messages with the stack and requires a bit more code).
Re: Compiler/Phobos/Types problem — panic level due to timing.
On Wednesday, 8 May 2019 at 11:53:34 UTC, Russel Winder wrote: On Mon, 2019-05-06 at 15:53 +, John Colvin via Digitalmars-d-learn wrote: […] pretty please show people it with UFCS: recurrence!((a, n) => a[n-1] + a[n-2])(zero, one) .dropExactly(n) .front Any particular reason for preferring this form over the original? For example, It is more readable, as the order of execution is unwinded.
Re: alias this and struct allocation
On Monday, 6 May 2019 at 14:48:56 UTC, faissaloo wrote:
I've been having some memory issues (referenced objects turning
to nulls for no apparent reason) and I was wondering if I've
misunderstood how allocation works when instantiating a struct
that uses alias this:
import std.stdio;
struct Parent {
int a;
}
struct Child {
Parent base;
alias base this;
int y;
}
auto myStructMaker() {
return new Child(Parent(10),20);
}
void main()
{
writeln(*myStructMaker());
}
In this example is the data in base guaranteed to exist?
Yes:
static assert(!__traits(compiles, Child.init.base is null));
Or is base definitely part of the allocation of Child on the
heap?
I would say, yes. Why do you think it is a contradiction?
Re: Mixin can't access library symbols?
On Friday, 3 May 2019 at 17:55:19 UTC, faissaloo wrote:
On Friday, 3 May 2019 at 17:51:39 UTC, Adam D. Ruppe wrote:
On Friday, 3 May 2019 at 17:48:50 UTC, faissaloo wrote:
How can I get a mixin to implicitly include the symbols from
its surrounding context? Is this possible?
What's your big picture goal? Do you have sample code you have
tried so far?
Also, are you talking mixin("string") or mixin template? They
work differently with symbols too.
My sample code is too big to be useful. The use of my mixin
looks like:
mixin(defState!("XEvent value;"));
But it tells me it can't find the symbol XEvent despite me
having used it elsewhere.
It's because XEvent is not visible in the scope, you need to
import the module it is contained in. mixin templates are used in
the call scope, not the defining scope.
You have some misunderstanding of D meta programming but you h
ave not given enough info to diagnose the problem.
You look to be using a string that represents a code string that
will be later mixed in(as a string mixin) but you are also using
a template mixin.
But most likely you simply need to add an "import ..." somewhere
to get XEvent in the scope. Sometimes this is a little tricky
because you want to generalize it so you have to do some weird
stuff and use mixin("import "~moduleName!T~";");
Re: What's best practice to use compound literals with structs and C-APIs?
On Thursday, 2 May 2019 at 07:11:37 UTC, Robert M. Münch wrote:
On 2019-05-01 19:13:54 +, Alex said:
Doesn't work because this seems to kick in some D releated
run-time stuff which lead to unresolved externals during
linking:
error LNK2001: Nicht aufgelöstes externes Symbol "...__initZ".
error LNK2001: Nicht aufgelöstes externes Symbol
"...__xtoHashFNbNeKxSQBtQBoQBfZm".
error LNK2001: Nicht aufgelöstes externes Symbol
"...__xopEqualsFKxSQBsQBnQBeKxQmZb".
Not sure, why this happens.
Found this bug: https://issues.dlang.org/show_bug.cgi?id=12374
It is closed now, because of inactivity, if you have a current
case - a reopen is welcome.
However... Not sure, maybe someone else has more knowledge
about this.
Thanks for the link, looks a bit related. I would need to see
if I can create a small case which shows the problem...
So, you generate D structs from C, right? If so, and if you
need the byRef at any cost - you could tweak the generator, so
byRef is generated for all structs.
Well, the generator is DStep... and I'm not sure if a general
"byRef" approach would make sense. And listing affected structs
manually will complicate the workflow again.
yeah...
What I'm irriated about is, that this works:
A tmp = {x,y};
return myfunc();
But this doesn't:
return myfunc(new A(x,y));
Or I haven't found a valid syntax to do it inline.
For me, this works:
´´´
void main()
{
myfunc(new A(5));
}
struct A{
int i;
}
void myfunc(A* myA){}
´´´
Re: GtkD slows down visual D keyboard
On Friday, 26 April 2019 at 14:50:17 UTC, Mike Wey wrote: On 26-04-2019 10:31, Amex wrote: When debugging under visual D, the keyboard response is slowed down to the extreme. This is a Gtk issue I believe. It only has to do with the keyboard. For example, if I hit F10 to step, it takes the ide about 10 seconds to "respond" and move to the next line... yet the mouse can access stuff instantaneous. I believe Gtk or GtkD is slowing down the keyboard input somehow and for some reason making debugging apps a nightmare since it literally takes about 100 times longer to debug than it should. searching google reveals: https://github.com/Microsoft/vcpkg/issues/4529 https://developercommunity.visualstudio.com/content/problem/42018/debugging-with-keyboard-very-slow.html "You somehow break keyboard shortcuts during debugging in VS if the application you're debugging is registering a callback with "SetWindowsHookEx" from user32.dll with hook ID "WH_KEYBOARD_LL". Don't call it in debug builds or add "if (!Debugger.IsAttached)" in front of the call to "SetWindowsHookEx" if the debugger is attached before the function is called. This brings debugging with keyboard back to the same speed as with the UI buttons for our application." This seems to be an issue with Gtk. I'm not sure if GtkD can do anything about it. Maybe somehow reroute the keyboard handler(first remove it from the hook then call it manually or reduce the number of calls to it). I can confirm that gtk call "SetWindowsHookEx" with the "WH_KEYBOARD_LL" ID upon initialization. As far as i can tell it doesn't provide a way to skip this. Any news about this? Do you think it can be fixed in some way?
Re: What's best practice to use compound literals with structs and C-APIs?
On Wednesday, 1 May 2019 at 14:59:48 UTC, Robert M. Münch wrote: On 2019-05-01 14:23:37 +, Alex said: However, to rebuild the same structure, auto ref parameters may be appropriate. https://dlang.org/spec/template.html#auto-ref-parameters That would need me to change myfunc which is not possible because the D binding is all generated from C code. Ok, I see. or you new A(...) in place Doesn't work because this seems to kick in some D releated run-time stuff which lead to unresolved externals during linking: error LNK2001: Nicht aufgelöstes externes Symbol "...__initZ". error LNK2001: Nicht aufgelöstes externes Symbol "...__xtoHashFNbNeKxSQBtQBoQBfZm". error LNK2001: Nicht aufgelöstes externes Symbol "...__xopEqualsFKxSQBsQBnQBeKxQmZb". Not sure, why this happens. Found this bug: https://issues.dlang.org/show_bug.cgi?id=12374 It is closed now, because of inactivity, if you have a current case - a reopen is welcome. However... Not sure, maybe someone else has more knowledge about this. or you use the byRef-pattern as shown in d-idioms https://p0nce.github.io/d-idioms/#Rvalue-references:-Understanding-auto-ref-and-then-not-using-it This again would need my to change the C bindings, which are generated. So, you generate D structs from C, right? If so, and if you need the byRef at any cost - you could tweak the generator, so byRef is generated for all structs.
Re: What's best practice to use compound literals with structs and C-APIs?
On Wednesday, 1 May 2019 at 12:47:22 UTC, Robert M. Münch wrote:
I use some C library that uses structs and many functions that
use pointer to structs as arguments:
struct A {...};
myfunc(A *myA);
In C you can do this to get a lvalue:
myfunc(&(A){...});
In D this doesn't work and I get an "is not an lvalue and
cannot be modified".
What's the correct D-ish way in such a case?
Look, even in C you have to workaround the case, where you want
to pass a value instead of a pointer. So, the proper question
would be, how to redesign, so that &(A){...} is not needed.
However, to rebuild the same structure, auto ref parameters may
be appropriate.
https://dlang.org/spec/template.html#auto-ref-parameters
or you new A(...) in place
or you use the byRef-pattern as shown in d-idioms
https://p0nce.github.io/d-idioms/#Rvalue-references:-Understanding-auto-ref-and-then-not-using-it
Not sure, which part is under your control...
Determime actual modules used
I need to determine the actual modules that are used in the project, not just imported but ones that actually are referenced. Any utility exists to do this?
Re: Call delegate from C++
On Wednesday, 24 April 2019 at 16:20:17 UTC, Nicholas Wilson
wrote:
How do you pass a delegate to a c++ function to be called by it?
The function to pass the delegate to is:
extern (C++) int
fakeEntrypoint(
extern(C++) void function(void* /*delegate's context*/)
func,
void* /*delegate's context*/ arg);
What I want is:
int entrypoint(scope void delegate() func)
{
return fakeEntrypoint(
// for some reason func.funcptr is void
function()
cast(void function(void*))func.funcptr,
func.ptr);
}
but that fails with
cannot pass argument cast(void function(void*))func.funcptr of
type
void function(void*) to parameter extern (C++) void
function(void*) func
It's clear that your delegate is not extern C++
int entrypoint(scope extern(C++) void delegate() func)
Re: alias fails to compile
On Monday, 22 April 2019 at 08:02:06 UTC, Arun Chandrasekaran
wrote:
What am I doing wrong here?
struct A
{
union B
{
int bb;
}
B b;
alias aa = b.bb;
}
void main()
{
A a = A();
// a.b.bb = 4; // works
a.aa = 4; // fails
}
https://run.dlang.io/is/kXaVy2
aa is a "static" semantic.
your statement a.aa does not get translated in to a.b.bb like you
think it does.
You are doing nothing any different than A.aa = 4.
which, when you realize this you'll understand the "need this"
error.
It's as if you are doing
struct A
{
union B
{
int bb;
}
B b;
}
alias aa = A.b.bb;
aa = 4;
which is like trying to say
A.b.bb = 4;
In D we can access "static" stuff using the object and so this
can make things look like the mean something they are not.
If you could magically pass the this to it using something like
UFCS then it could work.
import std.stdio;
struct A
{
union B
{
int bb;
}
B b;
alias aa = (ref typeof(this) a) { return };
}
void main()
{
A a = A();
a.b.bb = 4;
a.aa(a).bb = 5;
writeln(a.aa(a).bb);
}
But here a.aa is not aa(a) and UFCS does not work so one must
first access the alias and then pass the this.
Basically you are not going to get it to work. Just not how the
semantics works.
It would be nice if a.aa(a) could reduce to a.aa as is UFCS was
smart enough to realize it could pass it to the alias as this,
but it doesn't.
else one might could do
alias aa = this.b.bb;
and
a.aa = 4;
Re: Inherit enum members
On Sunday, 21 April 2019 at 20:58:19 UTC, Andrey wrote:
Hello,
I have got 2 enums. How to inherit one enum from another?
enum Key : string
{
K1 = "qwerty",
K2 = "asdfgh"
}
enum ExtendedKey : Key
{
E1 = "q1",
E2 = "w2",
E3 = "e3"
}
Result:
onlineapp.d(27): Error: cannot implicitly convert expression
"q1" of type string to Key
onlineapp.d(28): Error: cannot implicitly convert expression
"w2" of type string to Key
onlineapp.d(29): Error: cannot implicitly convert expression
"e3" of type string to Key
How to understand this?
I don't know why you want to do this, just use string directly.
enum ExtendedKey : typeof(EnumMembers!Key[0])
{
q = EnumMembers!Key[0]
}
would work..
Alternatively look at this thread:
https://forum.dlang.org/thread/irvtrixunermburvv...@forum.dlang.org?page=2
Where you can use the code and classes to subtype and emulate
enums.
Re: How to debug long-lived D program memory usage?
On Friday, 19 April 2019 at 03:27:04 UTC, Adam D. Ruppe wrote: On Friday, 19 April 2019 at 02:58:34 UTC, Alex wrote: Curious, what are these programs? A terminal emulator gui (like xterm), a detachable terminal emulator (like gnu screen), a slack client, an irc client, and a bunch of http servers including d doc search, a work program, and a personal utility. Ok, nothing useful ;) I was thinking you might be doing stuff like running a security system that did computer vision, or some type of advanced house monitoring and control(voice activated doors or something) ;) Could you not, as a quick fix, just reboot and automate restarting those? Maybe design an auto-restart which saves the state, shuts itself down and then relaunches itself and loads the data? This could be done as a fail safe when memory consumption get's too high. All of them would show growing memory time, some worse than others. You can see a lot of difference in them - gui programs, terminal programs, network server programs. But, I did write it all myself, so it could be a mistake I keep on making. So far, I basically tracked down the terminal emulator things to being inefficient scrollback storage. I made the structs smaller and limited the amount saved more than before and cut this by half. The ddoc search was keeping the index in memory, that's fixed, but it still shows growing usage over time. Of course, restarting that is trivial if need be, but still, I wanna make sure I am doing it right too - especially if it is one of my underlying libraries to blame. Gonna have to be one of those things you track down because it could be something as simple as the GC or something more serious. You might have hook in to the GC and just write out stats, I believe there is a stats collector somewhere though. Yes, indeed. I am starting to make serious progress now - mostly the fault is me storing excessive histories inefficiently. Should have been obvious in retrospect, but I didn't realize just how much overhead there was in my designs! D should have a very good memory statistics library built(I guess it has something with the switches)... since it should have no issues tracking memory usage. Every memory allocation must have a corresponding deallocation for stable programs. All allocations and deallocations have specific file locations or occur in the GC. I don't see why it would be difficult to monitor this stuff. As I mentioned, I generally never use new precisely so I can track this stuff myself and have a nice printout of memory usage when I need it and even verify the net memory allocation 0 zero on program exit. I haven't messed with the GC but I imagine it too shouldn't be hard to add the info too.
Re: How to debug long-lived D program memory usage?
On Wednesday, 17 April 2019 at 16:27:02 UTC, Adam D. Ruppe wrote: D programs are a vital part of my home computer infrastructure. I run some 60 D processes at almost any time and have recently been running out of memory. Each individual process eats ~30-100 MB, but that times 60 = trouble. They start off small, like 5 MB, and grow over weeks or months, so it isn't something I can easily isolate in a debugger after recompiling. I'm pretty sure this is the result of wasteful code somewhere in my underlying libraries, but nothing is obviously jumping out at me in the code. So I want to look at some of my existing processes and see just what is responsible for this. I tried attaching to one and `call gc_stats()` in gdb... and it segfaulted. Whoops. I am willing to recompile and run again, though I need to actually use the programs, so if instrumenting makes them unusable it won't really help. Is there a magic --DRT- argument perhaps? Or some trick with gdb attaching to a running process I don't know? What I'm hoping to do is get an idea of which line of code allocates the most that isn't subsequently freed. Curious, what are these programs? You might have hook in to the GC and just write out stats, I believe there is a stats collector somewhere though. I did this by replacing new and monitored and calculated the allocations. This didn't help for any GC issues but at least made sure all my allocations were correct. What you could do is something similar to this and just output stuff to a text file(that is written every so often). If they programs are not too large you could used named allocations that could then be graphed individually(or use the file locations, __FILE__, etc). Search and replace all new's and allocs with your custom ones and override the GC's. Should give you a good idea of what's going on.
Re: Subtyping of an enum
On Monday, 15 April 2019 at 20:36:09 UTC, Anton Fediushin wrote:
On Monday, 15 April 2019 at 14:20:57 UTC, Alex wrote:
On Monday, 15 April 2019 at 08:39:24 UTC, Anton Fediushin
wrote:
Hello! I am currently trying to add a custom `toString`
method to an enum so that:
1. Enum members would still have numeric values and can be
easily compared (things like `enum a { foo = "FOO", bar =
"BAR”}` won't do, I want `a.foo < a.bar)`)
2. More custom methods can be implemented in the future
Obvious solution is to wrap an enum in a structure and
utilize 'alias this' for subtyping like this:
```
struct Enum {
private {
enum internal {
foo,
bar
}
internal m_enum;
}
this(internal i) { m_enum = i; }
alias m_enum this;
string toString() {
// custom implementation of toString
}
}
```
This seems to work just fine for assigning and comparisons
but passing Enum as a function argument does not work:
```
void fun(Enum e) {}
fun(Enum.foo);
---
Error: function fun(Enum e) is not callable using argument
types (internal)
Cannot pass argument foo of type internal to parameter Enum e.
```
Of course, I could just define a bunch of functions that
accept my enum as the first argument and call them using UFCS
but it'd require to explicitly specify functions instead of D
taking care of that (toString() for structures is called
automagically by functions like writeln) and those functions
would hang around here and there totally unorganized. I
prefer to keep functions inside of structures and classes.
If there are other ways of achieving the same *and* keeping
code clean and organized, please share.
Thank you in advance,
Anton.
yes,
import std.stdio, std.meta, std.traits, std.conv;
enum _MyEnum : int { a,b,c}
struct _Enum(T)
{
T value;
alias value this;
// generate static field members
static foreach(e, v; EnumMembers!T)
{
pragma(msg, "static MyEnum "~to!string(v)~" =
MyEnum(T."~to!string(v)~");");
mixin("static MyEnum "~to!string(v)~" =
cast(MyEnum)(T."~to!string(v)~");");
}
}
alias _Enum!_MyEnum MyEnum;
void foo(MyEnum e)
{
writeln(to!int(e));
}
void main()
{
foo(MyEnum.a);
foo(MyEnum.b);
foo(MyEnum.c);
}
https://run.dlang.io/is/WOcLrZ
Note that value is never used, it just makes the cast work and
treats the struct as an enum. Not sure if there is a way
around that.
Thank you, this is the solution I have been looking for!
Yes, it is quite nice. D should simply allow enums to act as
structs, they are effectively the same.[meaning they should
should allow methods having methods]
You might want to add a little more functionality. I screwed up
the code when generalizing it, here is a bit better version:
https://run.dlang.io/is/yyuy77
Using the struct you can leverage all the power of op's such as
dispatching, assignment, etc.
Essentially one is just using a standard struct but using enum's
to define the names and values(since they are auto filled).
D should just do away with enums and allow one to create a enum
struct, e.g.,
struct S
{
enum : int
{
a,b,c
}
}
Of which enum S : int { a,b,c } is short hand when one does not
want to add new functionality or D could just treat enum like a
struct by allowing methods inside the enum.
The code I created essentially emulates this, one can make the
enum internal and private to hide it.
Re: Transparent cast from class to member pointer?
On Monday, 15 April 2019 at 15:07:10 UTC, Robert M. Münch wrote: On 2019-04-15 08:19:57 +, Ali ‡ehreli Bingo, I didn't know that I can do an 'alias this' using a function and not only a type... pretty cool. So, with several of these I can setup implicit conversions to different types. Thanks. Well, as I know, multiple alias this won't work yet... https://wiki.dlang.org/DIP66
Re: Subtyping of an enum
On Monday, 15 April 2019 at 08:39:24 UTC, Anton Fediushin wrote:
Hello! I am currently trying to add a custom `toString` method
to an enum so that:
1. Enum members would still have numeric values and can be
easily compared (things like `enum a { foo = "FOO", bar =
"BAR”}` won't do, I want `a.foo < a.bar)`)
2. More custom methods can be implemented in the future
Obvious solution is to wrap an enum in a structure and utilize
'alias this' for subtyping like this:
```
struct Enum {
private {
enum internal {
foo,
bar
}
internal m_enum;
}
this(internal i) { m_enum = i; }
alias m_enum this;
string toString() {
// custom implementation of toString
}
}
```
This seems to work just fine for assigning and comparisons but
passing Enum as a function argument does not work:
```
void fun(Enum e) {}
fun(Enum.foo);
---
Error: function fun(Enum e) is not callable using argument
types (internal)
Cannot pass argument foo of type internal to parameter Enum e.
```
Of course, I could just define a bunch of functions that accept
my enum as the first argument and call them using UFCS but it'd
require to explicitly specify functions instead of D taking
care of that (toString() for structures is called automagically
by functions like writeln) and those functions would hang
around here and there totally unorganized. I prefer to keep
functions inside of structures and classes.
If there are other ways of achieving the same *and* keeping
code clean and organized, please share.
Thank you in advance,
Anton.
Should have been
struct _Enum(T)
{
T value;
alias value this;
static foreach(e, v; EnumMembers!T)
mixin("static T "~to!string(v)~" =
cast(_Enum)(T."~to!string(v)~");");
}
Re: Subtyping of an enum
On Monday, 15 April 2019 at 08:39:24 UTC, Anton Fediushin wrote:
Hello! I am currently trying to add a custom `toString` method
to an enum so that:
1. Enum members would still have numeric values and can be
easily compared (things like `enum a { foo = "FOO", bar =
"BAR”}` won't do, I want `a.foo < a.bar)`)
2. More custom methods can be implemented in the future
Obvious solution is to wrap an enum in a structure and utilize
'alias this' for subtyping like this:
```
struct Enum {
private {
enum internal {
foo,
bar
}
internal m_enum;
}
this(internal i) { m_enum = i; }
alias m_enum this;
string toString() {
// custom implementation of toString
}
}
```
This seems to work just fine for assigning and comparisons but
passing Enum as a function argument does not work:
```
void fun(Enum e) {}
fun(Enum.foo);
---
Error: function fun(Enum e) is not callable using argument
types (internal)
Cannot pass argument foo of type internal to parameter Enum e.
```
Of course, I could just define a bunch of functions that accept
my enum as the first argument and call them using UFCS but it'd
require to explicitly specify functions instead of D taking
care of that (toString() for structures is called automagically
by functions like writeln) and those functions would hang
around here and there totally unorganized. I prefer to keep
functions inside of structures and classes.
If there are other ways of achieving the same *and* keeping
code clean and organized, please share.
Thank you in advance,
Anton.
yes,
import std.stdio, std.meta, std.traits, std.conv;
enum _MyEnum : int { a,b,c}
struct _Enum(T)
{
T value;
alias value this;
// generate static field members
static foreach(e, v; EnumMembers!T)
{
pragma(msg, "static MyEnum "~to!string(v)~" =
MyEnum(T."~to!string(v)~");");
mixin("static MyEnum "~to!string(v)~" =
cast(MyEnum)(T."~to!string(v)~");");
}
}
alias _Enum!_MyEnum MyEnum;
void foo(MyEnum e)
{
writeln(to!int(e));
}
void main()
{
foo(MyEnum.a);
foo(MyEnum.b);
foo(MyEnum.c);
}
https://run.dlang.io/is/WOcLrZ
Note that value is never used, it just makes the cast work and
treats the struct as an enum. Not sure if there is a way around
that.
Re: Subtyping of an enum
On Monday, 15 April 2019 at 13:38:33 UTC, Anton Fediushin wrote: This does work unless I want to use it like this: ``` fun(Enum.foo); --- Error: function fun(Enum e) is not callable using argument types (internal) cannot pass argument foo of type internal to parameter Enum e ``` This is correct. And you enforced this behavior as you said Enum.internal is private to make it inaccessible from any other place. All I want is a way to have > an enum that I could extend with my own methods. So... either you pass the internals of Enum somewhere, or you don't...
Re: Subtyping of an enum
On Monday, 15 April 2019 at 10:15:50 UTC, Anton Fediushin wrote:
On Monday, 15 April 2019 at 10:00:36 UTC, Alex wrote:
Enum.internal is private to make it inaccessible from any other
place. All I want is a way to have an enum that I could extend
with my own methods.
Something to make the following code work:
```
Enum a = Enum.foo;
Enum b = Enum.bar;
assert(a == Enum.foo);
assert(a < b);
assert(a.toString == "FOO");
assert(b.toString == "BAR");
writeln(a); // FOO
writeln(b); // BAR
```
This would:
´´´
struct Enum {
private {
enum internal {
foo,
bar
}
internal m_enum;
}
this(internal i) { m_enum = i; }
alias m_enum this;
string toString() {
if(m_enum == internal.foo)
return "FOO";
else
return "BAR";
}
}
void fun(Enum e) {}
void main(){
import std.stdio;
fun(Enum.init);
Enum a = Enum.foo;
Enum b = Enum.bar;
assert(a == Enum.foo);
assert(a < b);
assert(a.toString == "FOO");
assert(b.toString == "BAR");
writeln(a); // FOO
writeln(b); // BAR
}
´´´
Assuming, that automatic generation of "FOO" from foo was not
part of your question :-p
Re: Subtyping of an enum
On Monday, 15 April 2019 at 08:39:24 UTC, Anton Fediushin wrote:
Hello! I am currently trying to add a custom `toString` method
to an enum so that:
1. Enum members would still have numeric values and can be
easily compared (things like `enum a { foo = "FOO", bar =
"BAR”}` won't do, I want `a.foo < a.bar)`)
2. More custom methods can be implemented in the future
Obvious solution is to wrap an enum in a structure and utilize
'alias this' for subtyping like this:
```
struct Enum {
private {
enum internal {
foo,
bar
}
internal m_enum;
}
this(internal i) { m_enum = i; }
alias m_enum this;
string toString() {
// custom implementation of toString
}
}
```
This seems to work just fine for assigning and comparisons but
passing Enum as a function argument does not work:
```
void fun(Enum e) {}
fun(Enum.foo);
---
Error: function fun(Enum e) is not callable using argument
types (internal)
Cannot pass argument foo of type internal to parameter Enum e.
```
Of course, I could just define a bunch of functions that accept
my enum as the first argument and call them using UFCS but it'd
require to explicitly specify functions instead of D taking
care of that (toString() for structures is called automagically
by functions like writeln) and those functions would hang
around here and there totally unorganized. I prefer to keep
functions inside of structures and classes.
Isn't this a reason for passing your internals encapsulated, like
´´´
Enum EnumInstance = Enum(Enum.internal.foo);
fun(EnumInstance);
´´´
?
If there are other ways of achieving the same *and* keeping
code clean and organized, please share.
Thank you in advance,
Anton.
Otherwise, you could alwas define fun as
´´´
void fun(Enum.internal e) {}
´´´
but I assume, you want to avoid especially this.
In favor of my first proposition, also speaks the fact, that
Enum.foo is somewhat awkward w.r.t. your question, as you treat
the internal enum as a static member. Was this intended?
Re: bug in compiles?
On Friday, 12 April 2019 at 09:43:01 UTC, Jacob Carlborg wrote:
On 2019-04-11 20:13, Alex wrote:
The following code works when I comment out the static if
//static if (__traits(compiles, __traits(getAttributes, T)))
static foreach(a; __traits(getAttributes, T)) Attributes
~=
There seems to be absolutely no reason why this code would
fail with the static if but pass without it but in the first
case I get no attributes because the __traits compiles fails.
__traits(compiles, __traits(getAttributes, T))
vs
__traits(getAttributes, T)
How could it not compile in the first case and yet work in the
foreach?
The problem is that "__traits(getAttributes, T)" in it self is
not valid code. It needs to be part of larger expression or
statement. The following seems to work:
https://run.dlang.io/is/JWkdbQ
So this suggests that the error is due to an expression, I
thought compiles could take expressions ;/
onlineapp.d(17): Error: tuple(3) has no effect
3-int
@(3) int a;
__traits(getAttributes, a);
I use the same semantics all over the place and it seems to work:
static if (__traits(compiles, __traits(isTemplate, T)))
The same issue will happen, but I believe static if works here
without issue. If so this means that it is a bug. Maybe compiles
can have handle certain primitives(such as bools here) but not
others(such as tuples in the main case)?
It would make little sense to be forced to use a temp variable:
static if (__traits(compiles, auto x = __traits(isTemplate, T)))
(after all, a ; is not required either)
In fact, though:
Returns a bool true if all of the arguments compile (are
semantically correct). The arguments can be symbols, types, or
expressions that are syntactically correct. The arguments cannot
be statements or declarations.
If there are no arguments, the result is false.
import std.stdio;
struct S
{
static int s1;
int s2;
}
int foo();
int bar();
void main()
{
writeln(__traits(compiles)); // false
writeln(__traits(compiles, foo)); // true
writeln(__traits(compiles, foo + 1)); // true
writeln(__traits(compiles, + 1));// false
writeln(__traits(compiles, typeof(1))); // true
writeln(__traits(compiles, S.s1));// true
writeln(__traits(compiles, S.s3));// false
writeln(__traits(compiles, 1,2,3,int,long,std)); // true
writeln(__traits(compiles, 3[1]));// false
writeln(__traits(compiles, 1,2,3,int,long,3[1])); // false
So ultimately it suggests a bug in the compiler.
Re: bug in compiles?
On Friday, 12 April 2019 at 00:02:36 UTC, Seb wrote: On Thursday, 11 April 2019 at 23:55:18 UTC, Alex wrote: to judge people objectively. This isn't a nursery school and we are not 3 year olds... Exactly. So start behaving like a grown-up and professional. When you ask someone for help on the street, do you curse at him too? Um, where the hell did I "curse" at him? See, you are making up shit. Prove it! The posts are recorded! See, you do want this to a nursery school... You want your little rules and regulations and no cursing or you'll get soap in your mouth. You want to act like a grown up but you don't wanna be a grown up. Being a grown up sometimes requires you to not respond to people that you don't like. Yet you did! In the real world when someone says shit you don't like and you say shit back and then claim your in the right when you do the exact same shit doesn't cut it. See, you decided to become part of this problem... because you are part of the problem. You had nothing useful to say, nothing factual, nothing to add intelligently but you just decided on your own that you wanted to take sides play these little games. "Must be something else in your code because it works fine for me with this shortened example. https://run.dlang.io/is/o8xESB Seriously? Do you think you have ESP? Your code isn't even close to was talking about ;/ Here is is updated that shows the error. You seem to fail to understand that it is impossible for it to be my code. There is no way the static if should fail yet the static foreach pass. They both go together, that is is the whole point of the static if, to make sure the foreach works, yet it says it doesn't work when it in fact does(as commenting out the line proves)." I asked him if he thinks he has ESP, was that cursing him? I told him his code isn't close to what I was talking about, is that cursing? I'm asking a damn question and making a statement. I was trying to explain to him that there is no way in hell that he could be right(well, there is a small chances but why would he assume that?) because he of the nature of the problem. No where did I cuss him, attack him personally... it's something you guys decided to interpret as then you get offended and cause problems and you don't like me telling you to fuck off for saying I'm causing problems when you are causing problems. See, you guys are the source. You think your job is to police the world because you are special. If Bauss got offended or didn't like my town then he can chose to not respond to me ever again, that solve that problem. See, if I'm so fucking hostile to everyone and everyone never responds to me, guess the fuck what? No one responds, no problems. At most I could flood the site with useless posts or some shit like that(which I wouldn't do).. But instead, what happens is people like you that think you are do-gooders and you are going to save the world from ilk like me only make things worse. That is typical of people like you(which I say because you have proven you are that type of person by responding rather than just ignoring). At least if you had something useful to say then maybe it would matter. Instead, you say I am slinging poop and that gives you the right to sling poop back... but you also claim you are on the moral high ground. Now, that is my assessment of the situation. I claim it is based on facts. You can object, but you have the right to just STFU and let other people STFU. But I imagine you will want to continue being part of the problem. Seriously, what do you think will come out of your comments? They have no substance that can possibly have any good outcome. It's just like the shit I have said here, except my goal is to get you to realize that you are not contributing to the solution. Same as Parker with his need to police the the world. Do you really think it will make things better?
Re: bug in compiles?
On Thursday, 11 April 2019 at 23:04:46 UTC, Mike Parker wrote: On Thursday, 11 April 2019 at 22:41:32 UTC, Alex wrote: Seriously? Do you think you have ESP? Your code isn't even close to was talking about ;/ Here is is updated that shows the error. You seem to fail to understand that it is impossible for it to be my code. If you continue to attack people who are trying to help you, the moderators will stop approving your posts. The hostility is unwelcome here. If the number of your posts that have not been approved didn’t serve as a warning, then this does. Quick google search to help you with your problem: https://www.quora.com/How-do-I-develop-a-thick-skin-and-stop-getting-offended-over-everything https://www.arkansasonline.com/news/2019/feb/05/too-thin-skin-20190205/ https://medium.com/the-mission/welcome-to-the-thin-skinned-generation-where-everything-is-a-bloody-problem-8bd5cb336361 http://dare.wisc.edu/survey-results/1965-1970/emotional-states-and-attitudes/gg8 http://meanttobehappy.com/10-ways-you-too-can-stop-being-so-easily-offended/ You can't police the world. You seem to live in a PC fantasy world where where every little booboo is treated as a life and death situation. You are not helping with the world with your need to control it. What are you going to do when things get really bad in the world? Have a nervous break down? If you think the shit I say is hostile and attacking people you really have no clue what the real world is like. You seem to have control issues that you should get addressed if you are going to threaten people over moronic statements that you interpret with your bias to be hostile. I'm sorry, but I'm not going to play your games. Did you go after FeepingCreature? He was clearly more hostile than I was but I bet you didn't say a god damn thing to him... You want me to stop being "hostile" then you need to throw your badge in the trash and stop trying to police every conversation because you really are in no position to judge people objectively. This isn't a nursery school and we are not 3 year olds... and if you want to turn it in to that kinda atmosphere then you kiss my ass.
Re: bug in compiles?
On Thursday, 11 April 2019 at 19:42:05 UTC, Steven Schveighoffer
wrote:
On 4/11/19 2:13 PM, Alex wrote:
The following code works when I comment out the static if
//static if (__traits(compiles, __traits(getAttributes, T)))
static foreach(a; __traits(getAttributes, T)) Attributes
~=
There seems to be absolutely no reason why this code would
fail with the static if but pass without it but in the first
case I get no attributes because the __traits compiles fails.
__traits(compiles, __traits(getAttributes, T))
vs
__traits(getAttributes, T)
How could it not compile in the first case and yet work in the
foreach?
It should. Do you have a larger example? One that can be played
with?
-Steve
import std.stdio, std.traits, std.conv;
struct A(alias T)
{
static void foo()
{
static if (__traits(compiles, __traits(getAttributes, T))) //
Failing for some reason
static foreach(a; __traits(getAttributes, T)) pragma(msg,
to!string(a), "-", typeof(a).stringof);
}
}
void main()
{
@(3) int a;
(A!a).foo();
}
Commenting out the static if allows the foreach to pass and
everything works. The whole point of the static if is to let the
foreach work.
Both are only dependent on
__traits(getAttributes, T)
So if that can't compile then how could the foreach work?
https://run.dlang.io/is/WlXCIZ
Re: bug in compiles?
On Thursday, 11 April 2019 at 20:49:45 UTC, bauss wrote:
On Thursday, 11 April 2019 at 18:13:48 UTC, Alex wrote:
The following code works when I comment out the static if
//static if (__traits(compiles, __traits(getAttributes, T)))
static foreach(a; __traits(getAttributes, T)) Attributes ~=
There seems to be absolutely no reason why this code would
fail with the static if but pass without it but in the first
case I get no attributes because the __traits compiles fails.
__traits(compiles, __traits(getAttributes, T))
vs
__traits(getAttributes, T)
How could it not compile in the first case and yet work in the
foreach?
T is a local variable name passed to this code, which does
generally return an
error when used in certain ways:
int x;
Code!x; // Basically the code at the top
if I try to do too much with x I get `cannot use local `x` as
a parameter to a non-global template`. Usually when I try to
pass T to another template I get this error.
But some things work. But I can't for the life of me
understand why compiles is failing but the foreach loop is
working.
The problem is that I am using compiles quite often and either
I'm misusing it or it's got some bugs in it that worry me
because maybe they are silently failing?
Note that I get no errors in my code and I do get the
attributes so it is technically working.
It would be really nice to know why the compiles is failing,
e.g.,
pragma(compilesmsg, __traits(getAttributes, T)) spits out the
error.
Must be something else in your code because it works fine for
me with this shortened example.
https://run.dlang.io/is/o8xESB
Seriously? Do you think you have ESP? Your code isn't even close
to was talking about ;/
Here is is updated that shows the error. You seem to fail to
understand that it is impossible for it to be my code. There is
no way the static if should fail yet the static foreach pass.
They both go together, that is is the whole point of the static
if, to make sure the foreach works, yet it says it doesn't work
when it in fact does(as commenting out the line proves).
import std.stdio, std.traits, std.conv;
struct A(alias T)
{
static void foo()
{
static if (__traits(compiles, __traits(getAttributes, T))) //
Failing for some reason
static foreach(a; __traits(getAttributes, T)) pragma(msg,
to!string(a), "-", typeof(a).stringof);
}
}
void main()
{
@(3) int a;
(A!a).foo();
}
bug in compiles?
The following code works when I comment out the static if //static if (__traits(compiles, __traits(getAttributes, T))) static foreach(a; __traits(getAttributes, T)) Attributes ~= There seems to be absolutely no reason why this code would fail with the static if but pass without it but in the first case I get no attributes because the __traits compiles fails. __traits(compiles, __traits(getAttributes, T)) vs __traits(getAttributes, T) How could it not compile in the first case and yet work in the foreach? T is a local variable name passed to this code, which does generally return an error when used in certain ways: int x; Code!x; // Basically the code at the top if I try to do too much with x I get `cannot use local `x` as a parameter to a non-global template`. Usually when I try to pass T to another template I get this error. But some things work. But I can't for the life of me understand why compiles is failing but the foreach loop is working. The problem is that I am using compiles quite often and either I'm misusing it or it's got some bugs in it that worry me because maybe they are silently failing? Note that I get no errors in my code and I do get the attributes so it is technically working. It would be really nice to know why the compiles is failing, e.g., pragma(compilesmsg, __traits(getAttributes, T)) spits out the error.
Re: Overloads not returning appropriate info. [Field reflunkory]
On Tuesday, 9 April 2019 at 21:00:55 UTC, H. S. Teoh wrote: On Tue, Apr 09, 2019 at 08:49:17PM +, Alex via Digitalmars-d-learn wrote: On Tuesday, 9 April 2019 at 18:56:58 UTC, H. S. Teoh wrote: [...] My point has been and is that there is a better way that is more natural. I make no claims about anything else. It may be a cop out to say something that is a tautology but I make the claim as an emphasis that I believe that it is more true in this case than others. i.e., D's traits are PITA. Ok, they are not as bad as some things but I know they can be better since I have used other languages that have far more logical reflection(such as C#) than D. As I said, __traits was never designed to be user-friendly, or even "logical". It was supposed to be a quick-and-easy way to tap into compiler internals, and std.traits was supposed to be the proper API to introspection. But std.traits, as it stands, is far, far from what it ought to be, and so we have today's sorry situation. That's unfortunate... but at least they are generally pretty functional. I remember trying to do basic type comparisons in C#'s reflection and didn't have the capability(I think it got it later but I believe that was the time I left for D). I can understanding adding traits int he way it was, but at some point it has to be brought to the same standard as the rest of the language. It's just far too important to neglect. After all, Even most of phobos is using meta programming. (And on a side note: don't even get me started on is(...) expressions.) Anyway, since you seem to be passionate about this, this could be your chance of making std.traits what it ought to have been all along, or making a sensible reflection library that can for all practical purposes replace std.traits. The problem is, I believe to do it right, it should be done in the compiler(at least some changes) and I know virtually nothing about the design and internals, so it would be much more time consuming than I'd like). I feel if I were going to go down that route I'd rather spend time writing a compiler or getting better as functional programming. I, for one thing, would appreciate a nicer API to introspection than what we currently have. One of the main things that drew me to D was its metaprogramming capabilities, and while overall it has been a positive experience, there *are* flies in the ointment like __traits, is(...) expressions, etc.. If you or somebody else could come up with a saner way to do introspection in D, it'd be very much appreciated. Basically same here. D is one of those love/hate relationships ;/ Meta programming is the next stage of evolution of programming. It is necessary for simplifying the complex problems of the modern computing world. D does have quite a nice syntax for most of this and does reasonably well(Although I believe functional programming blows D's type system out the water since it deals with structural mapping directly without "special cases").
Re: Overloads not returning appropriate info. [Field reflunkory]
On Wednesday, 10 April 2019 at 02:19:42 UTC, Adam D. Ruppe wrote: On Tuesday, 9 April 2019 at 20:45:18 UTC, Alex wrote: On Tuesday, 9 April 2019 at 18:33:21 UTC, Seb wrote: Have you considered writing a DIP? No, because I expect it won't even be considered. You won't pass review if you don't show knowledge of the existing language, but there's a lot of people who are interested in a few changes. A few years ago, there was a proposal for a magical `meta` namespace that would call into the compiler for syntax sugar on CT reflection. The old idea was to replace `__traits(X, args)` with `meta.X(args)` - pure syntax change - but you could perhaps revive and expand that as the entry point to your new idea and get some people on board. Yeah, but that isn't really effective, virtually identical. I am talking about one level higher abstraction. I mean, it's all the same but I'd like things to be sorta based in oop and ranges(UFCS like stuff). I haven't though about it enough to know how it would work out but I imagine things could be done very nicely. E.g., some accessors get information and some process that information and one can combine and match as needed. X.Type.name, X.Members.Select!"foo".Memebers.Select!"bar"(assuming foo is an aggregate), etc. Range functionality could even be used to process arrays(I guess the return of the traits would need to be ranges). I'm skeptical of any reflection library, but compiler changes might be able to change that. The status quo for D's reflection libraries are: 1) weird bugs and/or omissions since the language does not let you express all the function parameter details as return values or local variables. 2) slow compile times (you said your thing was 10 seconds! that's utterly unacceptable) It actually is not to bad. I haven't done much testing but at least repeatedly calling the Reflect on the same base type added little overhead(it wasn't scaling linearly with the number of calls). So maybe it has a chance. Still will never be as efficient as doing it internally though. 3) not actually significantly easier to use than language built-ins (if they are actually easier to use at all!) So any library without compiler changes is, as of today, I believe *impossible* to get right, and getting as close as you can is horribly slow. So, your DIP would necessarily include language+compiler changes. And the compiler is *already* (almost) fully capable, so changing that needs to show that the change is worth it. Maybe you can do that, even little cosmetic things can indeed be a win, but to write a convincing case here, you'll need to compare and contrast various cases. I'd definitely rather see this in the compiler. I just no zero about Dmd's design and the specifics. It's not something I'm capable of doing without a significant investment that I'm not willing to do(only if I could add the design on top without having to "learn" everything about the compiler). My goal was to sort of bridge the gap of the ideal solution and what we have. Something I could use personally to solve most of the frustrations I have but I wasn't thinking of trying to make it in to something ideal.
Re: Overloads not returning appropriate info. [Field reflunkory]
On Wednesday, 10 April 2019 at 14:06:53 UTC, Adam D. Ruppe wrote: On Wednesday, 10 April 2019 at 10:18:35 UTC, H. S. Teoh wrote: [...] There's a little bit weird about it, but it makes sense. I used to find it hard to even remember how it works, but then I had to describe it for the book and it all came together. Consider this. [...] I wonder if there are some interesting patterns of nesting is's? is(...is(...is(...)...)...)
Re: Overloads not returning appropriate info. [Field reflunkory]
On Tuesday, 9 April 2019 at 18:56:58 UTC, H. S. Teoh wrote: On Tue, Apr 09, 2019 at 06:33:21PM +, Seb via Digitalmars-d-learn wrote: On Tuesday, 9 April 2019 at 16:30:53 UTC, Alex wrote: > On Tuesday, 9 April 2019 at 14:59:03 UTC, Adam D. Ruppe > wrote: > > [...] > I didn't say the language. The point with the language is > that it could have built in semantics to do reflection in a > inform way(__traits is somewhat uniform but messy and then > one has std.traits which then makes it not uniform). > > [...] Have you considered writing a DIP? I think the original intent was that __traits was supposed to be low-level, implementation-specific calls into the compiler, while std.traits is supposed to be the user-friendly syntactic sugar built on top that user code is supposed to use. Unfortunately, it turned out that people prefer using __traits directly instead, and std.traits hasn't quite been keeping up with new __traits (e.g., AFAIK __traits(compiles) does not have a std.traits equivalent), and is also less familiar to many people, so now we have a mishmash of code sometimes using __traits and sometimes std.traits. That may be the case but I recently saw some one here say "All the roads to hell are paved with good intentions", which isn't hyperbole. The better the initial plan the better things will turn out. Planning is the key to success, without it there is only luck. My point has been and is that there is a better way that is more natural. I make no claims about anything else. It may be a cop out to say something that is a tautology but I make the claim as an emphasis that I believe that it is more true in this case than others. i.e., D's traits are PITA. Ok, they are not as bad as some things but I know they can be better since I have used other languages that have far more logical reflection(such as C#) than D. Because D has such an extensive meta programming language(the best I've seen for procedural) it needs a well thought out and natural reflection scheme. traits works but the more I use it the more I believe it could have been done better. It's one thing to use it here and there, but when you use it everywhere the issues multiply. I think the library I through together at least demonstrates a much more natural way(and it was just a first attempt without any planning). I imagine something much better could be created with some proper planning and teamwork. My impression though is few people here actually care about such things.
Re: Overloads not returning appropriate info. [Field reflunkory]
On Tuesday, 9 April 2019 at 18:33:21 UTC, Seb wrote:
On Tuesday, 9 April 2019 at 16:30:53 UTC, Alex wrote:
On Tuesday, 9 April 2019 at 14:59:03 UTC, Adam D. Ruppe wrote:
[...]
I didn't say the language. The point with the language is that
it could have built in semantics to do reflection in a inform
way(__traits is somewhat uniform but messy and then one has
std.traits which then makes it not uniform).
[...]
Have you considered writing a DIP?
No, because I expect it won't even be considered. The typical
responses I have seen to this sort of thing is that "we already
have it". Hence why I decided to write my own lib, and then had a
few issues.
Andre did look in to some of the ideas and said he would pass it
off to some GSOC students to look in to making it better, so
maybe something will come out of that.
I believe that basically the compiler simply needs to present a
better interface in to reflection. This should have been done
from the get go but I guess __traits has been patched together
over time as as things were needed.
Essentially the compiler would need to do what I have done and
wrap __traits and std.traits in to a more uniform interface. It
would add an extra layer of indirection though since the wrapper
needs then to stay consistent with any traits changes.
My library works well but is incomplete and has some bugs to due
bugs in traits. It is, though, rather slow and I haven't worked
on fixing it. (actually it doesn't seem to add too much overhead
after the first call but I imagine that is due to the template
being instantiated already in the module, might multiply for each
new module it is used in)
What I'm thinking is that maybe it is better to have some range
like semantics used for reflection. I have thought about it much
but I got the idea earlier.
Type.Reflect.Accessor.Accessor.Selector.Selector.Accessor...
The idea is that one can access stuff from the type and then use
certain keywords to select and filter and then access more.
I say it is range like but I'm not sure if ranges would work or
not or if it would just be dispatching.
E.g.,
MyClass.Reflect.TemplateParameters.Select!int.Names
Would get the template parameters of MyClass, then select only
those with int and then get the names of those parameters.
(this could work in general for runtime too)
MyClass.SomeArray.Select("x.value == 4").name;
which is why I say it is sorta like ranges(which I'm thinking
more of piping).
I just haven't thought about it much and there doesn't seem to be
much interest in going this route... I think it would be a great
addition to D but others seem to not care or are more interested
in arguing to relatively insignificant issues.
Re: Overloads not returning appropriate info. [Field reflunkory]
On Tuesday, 9 April 2019 at 14:59:03 UTC, Adam D. Ruppe wrote: On Tuesday, 9 April 2019 at 14:42:38 UTC, Alex wrote: It basically proves my point that there are issues with D. The language is fine in this case, it is a bug in the library. I didn't say the language. The point with the language is that it could have built in semantics to do reflection in a inform way(__traits is somewhat uniform but messy and then one has std.traits which then makes it not uniform). Though, I don't think the library can be fixed because the language doesn't have facilities to express these things through libraries but I also don't see the point in having a library at all. You incur compile time and run time costs for stuff you probably don't need and introduce another layer of bugs. There is no runtime costs. The library may not be efficient but it is a better design. It abstracts most of the crap away and provides a very natural and uniform interface in to reflection. Ultimately the compiler itself should provide this information directly. It has all the information when it compiles and it can lazily instantiate whatever information it has to calculate when it is requested. It could be very efficient, it is just doing what __traits does but more naturally. Reflection should be a first class semantic in D given D's heavy meta programming capabilities. Some of the lower level features are a little weird to see*, but they are easy to use once you get to know them. * for example static if(is(typeof(overload) Params == __parameters)) to get the function parameter list (as the Params variable there). It is a little weird looking, but it isn't really hard to use. The problem is that there is a semantic that supposedly exists to dot he same but fails. So it is not about weirdness but about non-uniformity. Why does it have to be that way? There is no reason, it is also a hack in the compiler. WHy not just wrap that code with something sane like Type.Reflect!Parameters ? This is exactly what my library does and it is a more sane looking solution. It's that simple. You can't disagree, you know it looks better(we could argue about the precise syntax but it is much better and more informative than what you posted). Also, your snippet is meant to be used, later on, such as in a for each loop, when we could do static foreach(p; Type.Reflect!Parameters) vs static if(is(typeof(overload) Params == __parameters)) static foreach(p; Params) It's 50% savings in both line space and character space, it's much faster to understand, it is uniform and natural while the second case is ugly, confusing, and bloated. My point is that THERE IS NO NEED for such things. It is ALL about syntax. It's just wrappers. There is no new functionality. I'm just trying to make things "look" better because things that "look" better are easier to comprehend. Look better means that they are more uniform with common practices and experiences and allow for easier navigation in memory space. You may be ok with having to remember special cases here and their... but it is a defect. Suppose you program in 10 languages regularly, those special cases then are an order of magnitude more to remember... suppose you do other things with your life. If you don't and all you do is program D then you don't feel it as bad, if you do lots of other things then these are speed bumps that slows one down for no good reason at all(if you have one, besides, "some one has to code the new syntax and it takes work to make it better" then I'd like to hear it). What I see if you justifying bad syntax just to justify it because it exists. If I'm wrong you just have to give me meaningful reasons why that is not the case. I'm not looking to be confrontational, I'm looking to make things better. If you are right about what you claim then you can back it up, if not you can't except with fallacious arguments. My mind is willing to be changed as long as the change is provably good, else there is no point in going backwards. I think the only argument you have is "It already exists and works and is not too bad"... which may be a good enough argument for you but isn't for me. That type of argument can be used to prevent progress on anything. "The cave is already exists and works to keep us sheltered and is not that bad so we don't need to build a nice house with AC that takes work to do". If all you have ever lived in is a cave then you can't possibly know if the house is better. It has to be built first to compare and contrast. The secret is that there is always something better than something else and it always should be sought after, at least theoretically(sure there is the practical issue of time, I accept that, but I don't accept denial that their isn't something better). Hell, as much time that we have spent arguing over this shit we could have probably created a language feature
Re: Overloads not returning appropriate info. [Field reflunkory]
On Monday, 8 April 2019 at 21:52:59 UTC, Adam D. Ruppe wrote: On Saturday, 6 April 2019 at 12:20:28 UTC, Alex wrote: Error: variable `std.traits.ParameterDefaults!(foo).Get!1u.Get` only parameters or stack based variables can be `inout` so i think that is a bug in the phobos library see: https://forum.dlang.org/thread/qbqvkcoexxtlvlxob...@forum.dlang.org I appreciate you looking in to it instead of writing it off. It basically proves my point that there are issues with D. These issues tend too be subtle and creep in to code and then that causes problems. I have been thrown off several times and when things don't work out I assume it is my code and when it's not I've already trashed my code trying to figure out what was wrong with it. These are the real problems with D and they come from two things: Not having a uniform and direct interface for reflection. Not having proper unit testing done for traits. D is so heavy in meta programming that maybe it is time for a proper solution?
Re: const of AliasSeq is silently ignored
On Monday, 8 April 2019 at 19:56:50 UTC, Yuxuan Shui wrote: In this example: const(AliasSeq!(int, int)) a; pragma(msg, typeof(a)); // (int, int) This kind of make sense, since AliasSeq is not a "single" type. But silently dropping const seems bad, the compiler should probably report an error/warning in this case? kinda makes sense and making sense are two different things. It has to make sense to the compiler. While I see that you want to distribute const over the list, D is not designed to do this with anything that I know of. It could, without issue, but one must makes sure it does not contradict any other uses. If it doesn't then it could be a bonus feature. Normally though one expects const to work on it's argument and so this also suggests having a const AliasSeq. Since we can't have a const AliasSeq there may be no issue redefining it to me what you want. I agree that silently dropping things are bad. D does this sometimes and it can be a real pain.
Re: Templates - What's Up with the template keyword?
On Monday, 8 April 2019 at 12:23:28 UTC, Ron Tarrant wrote:
I'm digging into templates in an attempt to understand the
signals-n-slots replacement for the observer pattern, but I've
got a question I can't seem to find an answer for and an
example for which I'm unable to solve the error.
First, the question...
Your confusion arises in your understanding of meta programming
and templates. Templates are compile time expressions that use
parameters. They are exactly analogous to parameters in typical
programming but allow one to pass around CT information that
doesn't exist at run time.
It is not the statement itself that is a template but the fact
that it depends on a "template", which is a sort of abstract
variable.
class C(T)
template C(T)
struct(T)
interface(T)
void foo(T)()
etc...
are all things that depend on a template parameter T. One can say
that they are all "templated" or are "templates".
One can also say they are parameterized(meaning they take a
parameter, but the parameters are CT "objects".
Essentially template is the most general and the rest are just
syntactic sugar.
e.g.,
template CC(T)
{
class C
{
T t;
}
}
template CC is a "template"(just like a cookie cutter but that
can configure itself depending on what T is, as this example
shows that we can create a class with different type of t.
D has all kinda of stuff like this that help reduce the bloat of
templates. Sometimes you must use one method over another for
certain effects but usually you can pick and choose.
The idea is not to think of meta programming as something
different than normal programming. It is still programming and
there is enough of an overlap that it benefits one to realize
they are the same thing but are at different levels in the type
system. Meta programming works on the type hierarchy while
"runtime programming" works in the type hierarchy. Meta
programming is a super set of runtime programming.
The way I think of meta programming is that of coding runtime
code. Run time code codes binary code. If I create a statement
like
writeln("test");
I know that the code gets translated in to a call instruction,
pointers are used, "test" exists in some location in memory,
etc... it all is machine code though when I compile.
When I do something like this
foo!int();
I know that the first part of foo!int is "meta code" and it first
gets translated in to runtime code and then that code gets
translated in to machine code.
For example
void foo(T)(T s) { writeln(s); }
in this case, depending on what T is at compile time(which I get
to decide in some way and so I know exactly what it is at compile
time, in theory), foo takes on different versions.
if I call foo(3) then it is writeln(3) and T is an int(by
deduction in the compiler) and the compiler can even optimize out
certain things here because it also knows that 3 is known.(this
is CTFE) There is nothing to optimize in that example though.
if I call foo(readln()) then the the compiler cannot optimize out
but this code get translated in to writeln(readlin()) but T is a
string(since readln returns a string and the compiler can deduce
it).
But in general foo acts as all these possibilities(and all the
possibilities are known by the compiler because they have to be
known to compile and use).
So, what does templates do? They combine very similar code in to
meta blocks that can then be easily used. They allow constructing
very complex meta code such as
void foo(T)(T s) { static if (is(T == string)) writeln(s); }
and now foo is much more complicated because it has two
completely different behaviors depending on what T is. You can't
get that with run time code without a lot of work and it will
never be efficient. But here the compiler will eventually know
what T is and it can then choose the correct path at compile
time. The if will disappear and so no extra overhead exists at
runtime.
So, templates are very powerful things(the above doesn't even
dent their power) The idea to bear in mind is that anything in D
is a template if it takes a template parameter. Think of a
template as a drawing template used to sketch something. It isn't
the final result but it shapes the final result. It is more like
a blueprint or a program in and of itself.
I think the hard part for many is that they can't balance the
meta programming part with the run time part. This is very easy
though if one always just keeps track of which side one is
programming in and not to mix them up(mentally).
The meta programming part will always be obvious, it will depend
on template parameters and use meta programming constructs. There
are sometimes overlap between the two levels but it because
natural once one gets enough of an understanding.
The hardest part about D is that it has so much meta programming
stuff and there are sometimes bugs and special cases to do
things, but the grammatical
Re: Overloads not returning appropriate info. [Field reflunkory]
On Monday, 8 April 2019 at 12:26:28 UTC, Adam D. Ruppe wrote: On Sunday, 7 April 2019 at 17:42:58 UTC, Alex wrote: That is blatantly wrong. The code works EXACTLY the same way with and without using stringof. In some cases, yeah. In the general case, no. Your import hack* is only there because of stringof. Using the local symbol, there is no need to import the module. This means you avoid name conflicts with local symbols (like I pointed out in the linked post) and it has the potential to avoid protection violation errors, since you are no longer getting the symbol from your module; it is gotten somewhere else, ideally from its own module, and passed to you, which is allowed even for private or hidden symbols. It also just makes the code a lot simpler, so there's no more need to jump through hoops to debug it. But I've already said the point of using T.stringof is so that one gets what T is and that actually helps debugging. You don't think I didn't try using T first? Why would I type extra symbols if it work exactly fine the first time? The reason I added `~T.stringof~` which is 11 more chars than T.` was precisely because the code wasn't working and I was trying to figure out why. to claim that it's absolutely wrong in all cases is ignorant. I realize that in many cases it is unnecessary and in some cases it will break the code(requiring an import because one is not using the type but the id which is then hidden)... But as I said, I did a search and replace that it didn't change squat as far as the code. The main issue was using that typeof which you didn't catch cause you were too busy trying to make an issue out of stringof. The other issues either remain, even after using your "rule", or I had to refactor the code and use different traits(such as the one you recommended for fields). My point is that you are going ape shit over using T.stringof, you posted no real reasons why it is absolutely unnecessary yet claimed was after I already shown that it has some use. It's one thing to make a suggestion and say "You know, you don't have to use T.stringof since it will function better in general, try it without it and see if fixes your problems" rather than keep on beating a dead horse. * https://github.com/IncipientDesigns/Dlang_Reflect/blob/master/mReflect.d#L61 I have removed all T.stringof's in the code and I still get the exact same errors. That's the first step. Then, you clean up the hacks that were introduced to work around stringof's problems and get a better design that actually works, like passing private members from one module to another via alias parameters. I don't know what you are talking bout passing private members from one module using alias parameters. There is only one module that does the reflection and all the "passing" of private parameters are done INSIDE that module. If you mean that I should pass the initial class as an alias, well, I tried that initially and it worked for some things but failed for others so went back and forth between using alias and types. The problem is because there are issues in D's type system and when they create hard to track bug one has to screw with shit to figure out what is going on and that introduces dead ends which may or may not be modify the design incipiently... which is the whole damn reason I'm writing the reflection library in the first place... to avoid all these issues with traits and provide a common interface... I mean, half the shit in __traits looks like it could be in std.traits and there is no clear reason why there are two aspects of D that do essentially the same thing. Also there are many "holes" in traits that require compound solutions(such as filter members to specific types) which then creates ugly CT code(multiple nested loops). one could just open the source if there was anything to "hide" That's not necessarily true, it is possible to have code exclude private members. In fact, it is often considered good practice to do that for library releases for encapsulation! I'm not sure what you are talking about here. I assume you mean the body, which I'm not talking about. The body is irrelevant. You can't even get the body using __traits. I'm talking about if the symbol exists, private or not, one can see it in the source code since, for it to be marked private it must show up in the source. So, "private" does actually hide shit in the source code. It may hide the functionality/body/binary code, but marking a member private doesn't HIDE anything in the source. Protection is a runtime thing(except for CTFE). Protection *only* exists at compile time - at runtime, there's zero checks. There's nothing preventing you from passing a pointer to a private member, for example. No, you really are missing the point. Protection is a RUNTIME thing. Else one would just make all members public. Protection exists at compile
Re: What Does @ Mean?
On Monday, 8 April 2019 at 11:58:49 UTC, Ron Tarrant wrote:
This is frustrating and makes me feel like a complete newb.
Worse, it's impossible to search for. Ever try Googling a
single character?
The D documentation also doesn't seem to explain the meaning of
this or any other token. Sure, most of them are obvious, but
this one eludes me. All I can find is this:
https://dlang.org/spec/lex.html#tokens
Would someone please tell me what an at sign (@) means when
it's used like this:
bool isLeaf() @property
{
return children.length == 0;
}
In fact, I have no idea what @ means anywhere other than in an
email address. Is this a common thing in contemporary languages?
And while I'm asking, does an underscore have special meaning
when used either at the beginning or end of a variable name?
How about a double underscore?
I know underscores are sort of left over from C, but do these
characters have special meaning in D or are they simply a
convention... like T in a template definition?
Some of the attributes in D go with an "@".
https://forum.dlang.org/post/fiwfcsqmjsndcjixi...@forum.dlang.org
https://wiki.dlang.org/Language_Designs_Explained
https://dlang.org/spec/attribute.html
Re: Overloads not returning appropriate info. [Field reflunkory]
On Sunday, 7 April 2019 at 15:35:46 UTC, FeepingCreature wrote: On Sunday, 7 April 2019 at 03:47:25 UTC, Alex wrote: rules are meant to be broken. No they're not! Almost by definition not! More comprehensively, if you break a rule you take responsibility for the outcome. You wanna use stringof? "Don't use stringof for that." "rules are meant to be broken." -- "Wah, my code doesn't work, stringof is shit, bad design, fix D pls." Don't ask questions if you don't care about the answers. More importantly, don't ignore advice and then complain about it. You are a moron. Almost by definition? Here is some advice, don't be a pscyhopath. You come in to a thread without any desire to help in any way but to throw your 2c's and pretend you have something useful to say. You really are an idiot. The problems I faced had nothing to do with stringof. I did a search and replace and replaced ALL instances and the EXACT same code and issues were generated. That alone proves you are a moron. You can't expect to lead by authority. Give a good reason why I should avoid it and change my current ways and I will. Your code will break in surprising and unfixable ways. `stringof` is not *for* mixin. If you use it for mixin, you will be on your own design-wise. The language will not be changed to "fix" the "bugs" you run into. It will work until it won't work, and then you'll have to rewrite the entire thing anyway. Don't use stringof for mixin. go screw yourself. Please don't EVER respond to me again. I will ignore ALL your replies. I don't give a shit about your "advice". You clearly have no idea what you are talking about but have some need to act like an authority. I just hope you don't have a badge and a gun... People like you end up killing other people because they don't do shit the way you think they should. I'm just wondering if your that Adam guy... kinda fishy you both show up spouting the same BS and don't even back up your claims and when I say prove your claim by an example you spout the same BS. Morons make claims, experts prove them, neither of you have proven anything but you have made a lot of claims. It amazes me people like you freely exist in the world. Again, LEAVE ME ALONE! But I bet you won't! Psychopaths like yourself just can't shut the fuck up when told to go away.
