Re: pointer escaping return scope bug?
On Saturday, 19 November 2022 at 15:02:54 UTC, Nick Treleaven
wrote:
On Saturday, 19 November 2022 at 14:52:23 UTC, ag0aep6g wrote:
That's essentially just a function that returns its pointer
parameter. So the program boils down to this:
```D
@safe:
int* fp(return scope int* p) { return p; }
void main()
{
int* p;
{
auto lf = new int;
p = fp(lf);
}
assert(p != null); // address escaped
}
```
Which is fine, as far as I can tell. `lf` is not `scope`. And
when you pass it through `fp`, the result is still not
`scope`. So escaping it is allowed.
You do get an error when you make `lf` `scope` (explicitly or
implicitly). So everything seems to be in order.
OK, so how do I make `lf` implicitly scope?
Have the `int*` inside it to point to a local, or assign another
`scope int*` to it.
Re: Is defining get/set methods for every field overkill?
On Saturday, 19 November 2022 at 09:49:18 UTC, thebluepandabear
wrote:
On Saturday, 19 November 2022 at 09:26:49 UTC, Andrey Zherikov
wrote:
On Saturday, 19 November 2022 at 09:12:26 UTC,
thebluepandabear wrote:
That's the point many people have given here which is not
convincing him, even though it is quite great.
I think we all know the answer here
IMHO you are both right :)
You are speaking about API compatibility, `[]() {}()` speaks
about ABI compatibility. The latter makes sense in
long-running production software. So we know that there are no
issues in API compatibility but we don't know anything about
ABI.
I am too dumb to know what ABI is
ABI is short for application binary interface. Where API means
how you use another module in source code, ABI means how you
would use that module in assembly langauge or machine code.
If two versions of a library have the same ABI, the program using
the library does not have to be recompiled, only relinked to the
new library (which happens at runtime if it's a dynamically
linked library).
It tends to be of less importance in D than in C or C++. First, D
modules usually compile quickly enough that premade binaries
(which would be hard to keep up to date with the source code
headers) don't make sense. Second, DUB standardises the build
process so binaries aren't needed for user convenience either.
Maybe the most important remaining use case is building a library
that can be used from other languages.
Re: Is defining get/set methods for every field overkill?
On Saturday, 19 November 2022 at 09:26:49 UTC, Andrey Zherikov
wrote:
On Saturday, 19 November 2022 at 09:12:26 UTC, thebluepandabear
wrote:
That's the point many people have given here which is not
convincing him, even though it is quite great.
I think we all know the answer here
IMHO you are both right :)
You are speaking about API compatibility, `[]() {}()` speaks
about ABI compatibility. The latter makes sense in long-running
production software. So we know that there are no issues in API
compatibility but we don't know anything about ABI.
Yes, this is a good summary. Redefining a raw field as a
getter/setter pair keeps the API but breaks the ABI, so in some
cases conservative getters/setters can be justified.
Another problem with raw fields:
```D
struct S{int field;}
@safe clientCode()
{ auto s = new S();
doSomething();
}
```
This will break if S is rewritten as
```D
struct S
{ int field_;
auto field(){return field_;}
auto field(int val){return field_ = val;}
}
```
I though at first that breakage could still be avoided by instead
writing
```D
struct S
{ int field_;
ref field(){return field_;}
}
```
...but I tested and actually it does not work because in this
case `` takes the address of the getter function, not the
field.
Now, despite all this I don't think it'd be a good idea to write
everything to getters/setters just in case. The binary interface
issue is frankly secondary: most structs and classes are just
compiled along with their client code. And even separately
compiled libraries only have to do this if they strive to provide
a stable ABI between releases, which is not nearly always the
case. Nor needs to be.
But still the pointer problem in the above example stands, so
conservative getters/setters are justified in an API that's used
widely enough. But probably not for something internal to a ten
thousand line long package.
Re: Is defining get/set methods for every field overkill?
On Saturday, 19 November 2022 at 03:52:41 UTC, thebluepandabear
wrote:
Say you want to write 'SET' now whenever someone sets a
width/height value for the rect (as an example), and 'GET' when
someone gets the width/height value for the rect, what you
could do is do this:
```
class Rect2D {
int rectWidth;
int rectHeight;
int width() {
writeln("GET");
return rectWidth;
}
void width(int rectWidth) {
writeln("SET");
this.rectWidth = rectWidth;
}
int height() {
writeln("GET");
return rectHeight;
}
void height(int rectHeight) {
writeln("SET");
this.rectHeight = rectHeight;
}
}
```
Honestly, it may not be a magic bullet, but still useful.
Yes, this is what I meant. I did use the UFCS name inaccurately:
I believe UFCS means the ability to write `y.x(z)` in place of
`x(y, z)`, and maybe the ability to write `y.x = z` in place of
`y.x(z)`, but it does not mean the ability to omit empty
parenthesis in a function call. The latter is what enables
getters that don't break the API.
Re: Is defining get/set methods for every field overkill?
On Thursday, 17 November 2022 at 04:39:35 UTC, thebluepandabear wrote: I am debating whether or not I should add getter methods to these properties. On one hand, it will inflate the codebase by a lot, on the other hand -- in other languages like Java it is a good practice D has far less need for getters/setters than Java or C++. The reason is [Uniform Function Call Syntax](https://ddili.org/ders/d.en/ufcs.html). This means that a member of a `struct` or `class` can start out as a normal field and be later converted to getter/setter if needed, without breaking calling code. You still might want to use setters when you want to be extra conservative (client code taking address of a struct field will still break if your getter replacing it can't return by `ref`), but for the vast majority of purposes that is an overkill IMO.
Re: Making sense out of scope and function calls
On Sunday, 13 November 2022 at 19:06:40 UTC, 0xEAB wrote:
Why does only the latter sample compile?
The former leads to the following warning:
Are you using the `-preview=dip1000` compiler flag?
I didn't manage to reproduce this in a simple example of my own.
The closest I equivalent I accomplished is this:
```
enum LowerCaseToken { u, l, c }
struct Foo {
@safe:
int* dummy;
string[int][LowerCaseToken] _headers;
this(return ref int i)
{
dummy =
}
string[] getHeader(LowerCaseToken name) scope return
{
return _headers[name].values;
}
string[] getHeader(string name)() scope return
{
enum token = LowerCaseToken.l;
// Error. Remove to compile
auto x =
return this.getHeader(token);
}
}
@safe void main()
{
int x;
auto foo = Foo(x);
foo.getHeader!"h1"();
}
```
With `-preview=dip1000` this fails, but with a slightly different
message to yours, "cannot take address of `scope` parameter
`this` in `@safe` function `getHeader`". It's right to fail,
because you cannot have any pointer (or array, or class) to point
to a `scope` variable. D does not have any storage class for `x`
that would protect the int pointed to by `dummy`, because
`scope(Foo*)` means address of Foo is protected, not the address
of whatever `dummy` and `_headers` point to.
However, this error only happens if I try to create a pointer to
`this`, not when simply using `this`, plus the error is a bit
different, so I'm not sure what's going on.
(and why is the deprecation message printed twice?)
The function is a template. Perhaps it's instantiated twice.
Another possibility, you have instantiated the mixin template
that contains that function in your project twice.
Re: How to build DMD/Phobos on Windows
On Wednesday, 24 August 2022 at 18:06:29 UTC, Dmitry Olshansky wrote: It's been a long time but I've found some spare hours I want to devote to finally updating our std.uni to Unicode 14 (soon to migrate to 15 I guess). Thanks, much appreciated! So what is the canonical way to build D on Windows? Any pointers would be greately appreciated. Don't know since I don't use Windows anymore but if all else fails it probably works on WSL.
Re: How to use a non-static objects in string `mixin`?
On Saturday, 27 August 2022 at 13:20:13 UTC, hype_editor wrote: I need to use function `eval` sometimes, but compiler throws an error: `Error: variable `firstOperand` cannot be read at compile time`. You're probably misunderstanding `mixin`. It does not work like an eval function at Lisp or JavaScript or such. Instead, it evaluates it's contents at compile time, meaning that you can only use compile-time data in it, `enum` variables and template arguments for example. Because the operator is not known at compile time, this means you need something else. Switch statement Paul Backus suggested is one option. You could alternatively try an associative array that maps the operators to the respective functions, something like (untested): ```D enum opMap = [ "+": (double a, double b) => a+b, "-": (double a, double b) => a-b, //... ]; //in the eval function return opMap[operator](firstOperand, secondOperand); ```
Re: DIP1000
On Friday, 24 June 2022 at 05:11:13 UTC, Ola Fosheim Grøstad wrote: No, the lifetime is the same if there is no destructor. Being counter intuitive is poor usability. It depends on whether you expect the rules to be smart or simple. Smart is not necessarily better, as the Unix philosophy tells you. I'm sure you have experience about programs that are unpredictable and thus frustating to use because they try to be too smart.
Re: Bug in dmd?
On Tuesday, 14 June 2022 at 23:56:58 UTC, Andrey Zherikov wrote: On Tuesday, 14 June 2022 at 21:44:48 UTC, Dukc wrote: No idea. The functions seems indeed to be exactly the same, so I assume this is a DMD bug. It cannot be a bug in `std.sumtype`, since that would trigger in both of the templates. This definitely triggers some bug in DMD because this `private void printHelp ...` function is not really `private` as it's called from [another module](https://github.com/andrey-zherikov/argparse/blob/bug/source/argparse/internal.d#L786) and DMD doesn't catch this. Now when I think of it, perhaps the fact that private `printHelp` has the same name as the public `printHelp` is somehow confusing dmd. If you try to rename the private `printHelp` and it's call in the public one to something else, you might get some insight on what triggers this behaviour.
Re: Bug in dmd?
On Tuesday, 14 June 2022 at 13:39:12 UTC, Andrey Zherikov wrote:
I have [pretty simple code in my
library](https://github.com/andrey-zherikov/argparse/blob/bug/source/argparse/help.d#L27-L47):
```d
alias CC = SumType!(AA,BB);
struct AA {}
struct BB
{
CC[] c;
}
private void ppp(T, Output)(auto ref Output output, in
CommandArguments!T cmd, in Config config)
{
auto cc = CC(AA()); // (1)
}
private void printHelp(T, Output)(auto ref Output output, in
CommandArguments!T cmd, in Config config)
{
auto cc = CC(AA()); // (2)
}
void printHelp(T, Output)(auto ref Output output, in Config
config)
{
ppp(output, CommandArguments!T(config), config);
printHelp(output, CommandArguments!T(config), config);
}
```
[Line (2)
produces](https://github.com/andrey-zherikov/argparse/runs/6880350900?check_suite_focus=true#step:5:12) `undefined reference to '_D3std7sumtype__T7SumTypeTS8argparse4help2AATSQtQm2BBZQBl6__dtorMFNaNbNiNfZv'` (it demangles to `pure nothrow @nogc @safe void std.sumtype.SumType!(argparse.help.AA, argparse.help.BB).SumType.__dtor()`)
If I comment line (2) then everything is good (no link errors).
Note that there is the same code at (1) which doesn't produce
any error. Any idea what's going on?
No idea. The functions seems indeed to be exactly the same, so I
assume this is a DMD bug. It cannot be a bug in `std.sumtype`,
since that would trigger in both of the templates.
BTW, thanks for taking the effort to write your question this
well (demagling, link to your library and all).
Re: What's a good way to disassemble Phobos?
On Saturday, 30 April 2022 at 18:49:27 UTC, Adam D Ruppe wrote: On Saturday, 30 April 2022 at 18:18:02 UTC, Dukc wrote: I'm looking for something where I could search for the call to the DRuntime functions in question, from an already combined .o or .a. What do you suggest? I'm on Linux. objdump -d works on .o files Indeed, this seems workable output. Thanks.
What's a good way to disassemble Phobos?
I have figured out that my development build of Phobos is for some reason including instances of `__cmp` and `dstrcmp` templates from DRuntime in the Phobos binary. Since `-betterC` client code does not link Phobos in, it fails if it tries to use those functions. The problem: how do I track down what includes those functions in the Phobos binary? The -vasm switch of DMD gives a neat output, but I can get it to only show the disassembly of files I'm compiling (not already combined files), and before the linking phase. So no info where the function calls point to. I also tried ndisasm. It can disassemble already compiled binaries, but it's output is utter trash. It can't even figure where a function begins or ends, let alone displaying their name. Instead it displays just a sea of `add` instructions for the areas between the functions. I'm looking for something where I could search for the call to the DRuntime functions in question, from an already combined .o or .a. What do you suggest? I'm on Linux.
Re: How to use destroy and free.
On Saturday, 30 April 2022 at 11:37:32 UTC, Tejas wrote: Hell, just using `scope int[] i` should be enough to trigger deterministic destruction, no? `typecons`'s `Scoped!` template can be used if 100% guarantee is needed _and_ the memory has to be stack allocated Didn't think of that. To be frank, I don't know if `scope int[] i` means deterministic destruction. `Scoped` does IIRC.
Re: How to use destroy and free.
On Sunday, 24 April 2022 at 21:00:50 UTC, Alain De Vod wrote:
Is this a correct program to explicit call destroy & free ?
```
void main(){
int[] i=new int[1];
import object: destroy;
destroy(i);
import core.memory: GC;
GC.free(GC.addrOf(cast(void *)(i.ptr)));
}
```
A few picks.
1: You do not need to import `destroy`. Everything in `object` is
automatically imported.
2: As others have said, destroying an int, or an array if them,
is meaningless, since they do not have destructors. The only
thing your call does is to set `i` to `null`. In this case it
means that there are no more references to the array, so the
garbage collector can collect it at some point.
3: Because `i` is now null, `GC.free` also does nothing. If you
had something that really mandated using `destroy`, you'd want to
use `destroy!false(i)` to avoid setting `i` to `null`.
4: Manually freeing garbage collected memory is just as dangerous
as freeing manually managed memory. It's preferable to just let
the GC collect the memory. Also like said, there's probably no
point to allocate with GC in the first place if you're going to
manually free the memory.
5: If you're in a hurry to free the memory, a safer way is to
call `GC.collect`. It will most likely free your old data
immediately. Don't trust it quite 100% though, since it's
possible that some unlucky bit pattern in your remaining data,
that isn't really a pointer, "points" to your old data and it
won't get collected. Using a precise GC would eliminate that risk
I think.
This is rarely a problem though, as long as you either don't do
anything mandatory in destructors, or use `destroy` before
forgetting the data. The GC can still usually free the majority
of your memory.
Re: print ubyte[] as (ascii) string
On Thursday, 30 December 2021 at 09:34:27 UTC, eugene wrote:
```d
char[] s = cast(char[])ioCtx.buf[0 ..
strlen(cast(char*)ioCtx.buf.ptr) - 1];
// -1 is to eliminate terminating '\n'
writefln("got '%s' from '%s:%d'", s, client.addr, client.port);
```
Is there some more concise/elegant way to do that?
Try `auto s = fromStringz(cast(char*)ioCtx.buf.ptr)`.
Re: Why do we have Dmain?
On Friday, 22 October 2021 at 07:00:25 UTC, Mike Parker wrote: The entry point for your program is a function `_start`. That's implemented in the C runtime, which all D programs depend on. It in turn calls `main`, as it does for C and C++ programs. It is possible, in both C and D, to write your own `_start` and not depend on the C runtime. This is something you want to do only if necessary though - C runtime is so small that you don't want to drop it for any realistic desktop or even a smartphone program. The usual reason to do this is if there is no C runtime easily available - meaning mainly embedded targets.
Re: better c fibers
On Tuesday, 21 September 2021 at 09:37:30 UTC, Abby wrote: Hi there, I'm new in dlang I specially like betterC. I was hoping that d fibers would be implemented in without using classes, but there are not. Is there another way how to use async/await in dlang better c? Thank you for your help Abby A C or C++ concurrency library should work. Another option, if you just want fibers but not true concurrency, would be to do some assembly trickery. Probably not too hard if you know assembly, but not very portable. If the reason you're using `-betterC` is targeting asm.js or WebAssembly, you will need to use the JavaScript APIs of your environment for concurrency.
Re: Array permutations
On Saturday, 11 September 2021 at 19:37:42 UTC, Vino wrote:
Request your help on the below to print the below array as
"Required output", Was able to get these values
"[1,2],[2,3],[3,4],[4,5]" by using list.slide(2), need your
help to get values "1,3],[1,4],[1,5],[2,4],[2,5],[3,5]"
```d
import std;
auto slideEnds(List)(List list, size_t slideLen)
{ return list.slide(slideLen).map!(window => [window.front,
window.back]);
}
void main()
{ auto list = [1,2,3,4,5];
iota(2, list.length)
.map!(slideLen => list.slideEnds(slideLen))
.joiner
.writeln;
}
```
This almost does the trick. It leaves out `[1, 5]` for some
reason I didn't bother to check though.
Re: Ali's Book - Programming in D
On Friday, 10 September 2021 at 22:26:34 UTC, Ali Çehreli wrote: https://bitbucket.org/acehreli/ddili/commits/ Ah it's there - gotta remember that place if I want to make corrections. Good book - It's the one that got me up to speed with D before I was commited enough to pay for anything. Now while I'm talking, I'll tell the one error I have already spotted, in the `ranges` chapter. It claims that `std.range.generate` calls the underlying function on `front`, not `popFront`. This used to be true long ago, but nowadays the call is done on `popFront` and the call result is cached for `front`.
Re: How to Fix Weird Build Failure with "-release" but OK with "-debug"?
On Wednesday, 21 July 2021 at 14:15:51 UTC, Steven Schveighoffer wrote: 2. It's hard for me to see where the null dereference would be in that function (the `bool` implementation is pretty simple). -Steve DMD complains about dereferences in three different lines. I suspect it's `this` reference that is `null`.
Re: Can static variables in methods be local for each object?
On Tuesday, 20 July 2021 at 09:24:07 UTC, Mark Lagodych wrote:
Is there a way to make myvar local to each instance of `X`
without making it a variable of `X`? Just curious.
Yes.
```d
import std.stdio;
class X {
int x(int param) {
static int[typeof(this)] myvar;
if (param == 0) return myvar.get(this, 1234);
else return myvar[this] = param;
}
}
void main()
{
X x1 = new X;
X x2 = new X;
x1.x(0).writeln; //1234
x2.x(0).writeln; //1234
x1.x(17).writeln; //17
x2.x(0).writeln; //1234
x1.x(0).writeln; //17
x2.x(0).writeln; //1234
}
```
However, this is definitely not recommended. When you are calling
a function with any particular object and argument set, you want
it to do the same thing and return the same result, regardless of
what's called before. Otherwise you're making debugging much more
difficult than it needs to be.
This means that `static` variables should generally be used only
for two things:
1: data that is only set at the beginning of the program, or at
first use, and then left to the initial value.
2: caching results of expensive computation. Even this is a bit
controversal, as it's easy to screw up - often it's just better
to split the function in two, and let the caller to cache the
results.
In this case, consider passing `myvar` explicitly:
```d
import std.stdio;
class X {
int x(int param, ref int[typeof(this)] myvar) {
if (param == 0) return myvar.get(this, 1234);
else return myvar[this] = param;
}
}
void main()
{
X x1 = new X;
X x2 = new X;
int[X] myvar;
x1.x(17, myvar).writeln; //17
x2.x(0, myvar).writeln; //1234
x1.x(0, myvar).writeln; //17
x2.x(0, myvar).writeln; //1234
myvar = null; //Forget all calls made so far
x1.x(0, myvar).writeln; //1234
x2.x(0, myvar).writeln; //1234
}
```
Re: Why can't we transpile C++ to D?
On Thursday, 10 June 2021 at 15:09:02 UTC, Tejas wrote: Sorry, I'm rather ignorant when it comes to this, but why can't we use [pegged](https://github.com/PhilippeSigaud/Pegged) to transpile C++ code to D? Then we won't need a nogc compatible std library and so many other things could get easier, like getting legacy code to use Dlang. It might not be worth it for C+17 and beyond, but older codebases could benefit significantly, right? This is article is about transpiling old C++ to newer C++, but the same problem applies with translating C++ to D: https://scottmeyers.blogspot.com/2015/11/the-brick-wall-of-c-source-code.html
Re: coreutils with D trials, wc, binary vs well formed utf
Is there a(n easy-ish) way to fix up that wc.d source in the
blog to fallback to byte stream mode when a utf-8 reader fails
an encoding?
Rewrite `toLine`:
```
Line toLine(char[] l) pure
{ import std.array : array;
import std.algorithm : filter;
import std.utf : byDchar, replacementDchar;
auto valid = l.byDchar.filter!(c => c!=replacementDchar).array;
return Line(valid.byCodePoint.walkLength,
valid.splitter.walkLength);
}
```
This just ignores malformed UTF without counting it in. It has
one problem though, for some reason it seems to ignore one
character after a malformed cone unit. I don't know why.
Re: dlang opengl / gl / glu /glut library.
On Sunday, 18 April 2021 at 23:36:58 UTC, Alain De Vos wrote: When doing graphics the number of functions explodes. So one needs always a list, compare to a header file in c. If there are "modern" alternatives to opengl feel free. More modern from which perspective? Simpler to use (non-inclusive list of options: SDL2/Allegro/SFML bindings, cairod, DLib, dgame)? Or more modern from GPU acceleration perspective (you're probably wanting derelict-vulkan or derelict-bgfx)?
Re: Dlang equivalent of #define/#ifdef : not... version
On Tuesday, 20 April 2021 at 23:58:46 UTC, Steven Schveighoffer
wrote:
static if(i_am_a_feature) {
...
}
This would be correct if `i_am_a_feature` would be always
defined, just set to `false` if not existent. But I think the
idea was to not define the symbol at all if feature does not
exists. In that case, the condition should be `static
if(is(typeof(i_am_a_feature)))`.
Re: How to get Laptop battery level
On Monday, 22 February 2021 at 21:14:48 UTC, Dukc wrote: Note that DGame seems to be currently unmaintained - it might have some bits that do not compile anymore. SDL2 is a commonly used library though - you should be able to find more examples about it if you need to. Plus, the example I linked is not really the simple minimalistic one you want if battery level is all you want to figure out. Probably the derelict-sdl2 front page is what you're looking for that instead: https://code.dlang.org/packages/derelict-sdl2
Re: How to get Laptop battery level
On Monday, 22 February 2021 at 20:59:01 UTC, Greatsam4sure wrote: Dlang is a system programming language. How do I access the battery level of my system using code in dlang? As a systems language, D could access the hardware interface directly, if you knew it and loaded your program as a kernel driver - if your operating system lets you do that. Now, I don't think that was the most practical way to approach the problem :-). Instead, I recommend you use the SDL2 multimedia library to give you a more portable interface. Usage example in D here: https://github.com/Dgame/Dgame/blob/master/source/Dgame/System/Battery.d Note that the D module I linked does not contain the machinery to initialize SDL2. This module seems to contain that: https://github.com/Dgame/Dgame/blob/master/source/Dgame/Window/Window.d Note that DGame seems to be currently unmaintained - it might have some bits that do not compile anymore. SDL2 is a commonly used library though - you should be able to find more examples about it if you need to.
Re: Profiling
On Tuesday, 9 February 2021 at 16:39:25 UTC, Dukc wrote: You may have or may not have done it wrong, but in any case this is a bug. If you do something wrong, the program should tell you what you did wrong, instead of telling you that character '-' does not belong to middle of a long int. Oh wait a bit. The stack trace shows calling some function of 'app.d' - that's presumably your program. I wonder why it's being called - aren't you supposed to be viewing the profiling results instead of profiling? I'm not sure what's happening.
Re: Profiling
On Tuesday, 9 February 2021 at 07:45:13 UTC, JG wrote: Is d-profile-viewer no longer working? Or did I do something wrong? You may have or may not have done it wrong, but in any case this is a bug. If you do something wrong, the program should tell you what you did wrong, instead of telling you that character '-' does not belong to middle of a long int. You can try older d-profile-viewers as a workaround. Or you can try different ways to invoke the profile viewer or to profile different programs and see if you can pinpoint the cause.
Re: Open question: what code pattern you use usually for null safety problem
On Thursday, 14 January 2021 at 18:24:44 UTC, ddcovery wrote: This is only an open question to know what code patterns you usually use to solve this situation in D: if(person.father.father.name == "Peter") doSomething(); if(person.father.age > 80 ) doSomething(); knowing that *person*, or its *father* property can be null Probably the incremental check solution. A helper function if I find myself doing that more than two or three times. On the other hand, I don't have to do this that often. I usually design the functions to either except non-null values, or to return early in case of null.
Re: Why many programmers don't like GC?
On Thursday, 14 January 2021 at 14:28:43 UTC, Виталий Фадеев wrote: On Wednesday, 13 January 2021 at 18:58:56 UTC, Marcone wrote: I've always heard programmers complain about Garbage Collector GC. But I never understood why they complain. What's bad about GC? How write quickly without GC ? In DMD style: never release memory! This is not an option for long-running programs though, nor for anything that otherwise uses significant amounts of memory. Better to just use the GC if unsure.
Re: DConf talk : Exceptions will disappear in the future?
On Monday, 4 January 2021 at 15:39:50 UTC, ludo456 wrote: Listening to the first visioconf of the Dconf 2020, titled Destroy All Memory Corruption, (https://www.youtube.com/watch?v=XQHAIglE9CU) Walter talks about not using exceptions any more in the future. He says something like "this is where languages are going" [towards no using exceptions any more]. I don't think exceptions are going anywhere. It might be that new libraries tend to avoid them (to work with @nothrow and @live), but there is no reason to banish them from the whole language - that would only result in huge breakage for limited benefit. And I suspect Walter didn't mean all code -just the relatively low-level stuff that might want to use `@live`. Even if he did, community will force him to reconsider.
Re: Floating point values in structs.
On Friday, 18 December 2020 at 16:18:12 UTC, Dave P. wrote: If the compiler is going to introduce the overhead of initializing all the variables anyway, why set it to nan when integer types get set to the useful default of 0? Consider default value of `int*`. It is `null`, not a pointer to a newly-allocated 0. Most would probably agree that `null` works better, because it stands for "empty". 0 may or may not, depending on context. It's this philosophy with floating-point values also. `0.0` might seem like a value when no value is intended, with `nan` there are no ambiguities. More about this: https://digitalmars.com/articles/b81.html https://dlang.org/blog/2018/10/17/interfacing-d-with-c-arrays-part-1/
Re: Is there a standard function that combines take() and popFrontExactly()
On Friday, 11 December 2020 at 19:07:23 UTC, realhet wrote:
I've just made this unicode wordreplacer function working, but
It seems not too nice and functional-ish.
Are there ways to make it more simple?
To answer the title, yes there is:
```
foreach(isWord, len; str.map!fun.group){
auto act = ().refRange.take(len).text;
res.put(isWord && act==from ? to : act);
}
```
But personally I think it does not pay to try to be more
functional than what this snippet already is. The most important
thing is that the program is functional on the high level. This
means avoiding globals and static variables (`pure` may help),
big monolithic functions, god classes and functions which get
needless info by their parameters. Being functional in the low
level is secondary and not always worth it.
Re: where is the memory corruption?
On Wednesday, 9 December 2020 at 20:35:21 UTC, Jack wrote: the output is "h" rather "hello". What am I missing? In the sayHello function, you are converting a pointer to utf16 character into utf8 string, not utf16 string to utf8 string. Convert the C wstring to a D `wstring` first (std.string.fromStringz).
Re: To use or not immutable?
On Wednesday, 9 December 2020 at 16:47:43 UTC, Jack wrote: Do you use it in your code base? are there some design flaws, like there's in C++'s const, which I'm not aware of? There are downsides, Jonathan Davis has written about them: http://www.jmdavisprog.com/articles/why-const-sucks.html But the downside of D's `const` or `immutable` are mainly that you can't use them everywhere you might wish to. A good rule of thumb is that if you can get it to pass compilation as `const` or `immutable` without any hacks, there is no problem going ahead with it.
Re: how to print progress of a long running parallel() loop?
On Monday, 7 December 2020 at 08:16:50 UTC, mw wrote: r = Parallel(n_jobs=2, verbose=10)(delayed(sleep)(.2) for _ in range(10)) to print out the progress. How to do this in D's parallel loop? thanks. Allocate a `shared int` before the foreach loop. In the loop when, let's say `!(i & 0xFFF)`, atomically increment the shared variable and print it's number. Disclaimer: no experience about using `shared`, but this is what I'd try.
Re: Automatic update system
On Thursday, 26 November 2020 at 12:13:59 UTC, vnr wrote: Hello, I have a program written in D which is open-source on GitHub. I would appreciate it if, when I release a new version, users would be notified by the program and that it offers an automatic update, i.e. the user doesn't have to reinstall the whole repository himself, but that it is updated automatically. I haven't found any packages that directly meet my needs, but in the meantime I imagine that I will have to use the GitHub API, as well as Curl to make such a system. Do you have any resources or suggestions as to how I could implement this? Thank you! Make it a DUB package. It does not update 100% automatically, but notifies when updates are available. You could also make an auto-updater by hand, but that requires a networking library and won't work anyway if the user does not have permissions to change the executable. This is often the case, as the often recommended places to store the programs are `/usr/bin/` or `c:/program files/`. Neither is accessible by default priviledges. In addition, it is a lot more work to implement than making a dub package. I don't recomment absent a strong reason. If you publish your program in some other package format (apt, rpm, flatpak or nix for example), you can try to get your package into some official repository. There you can publish updates easily, and the program gets updated among the regular software updates the users do.
Re: Simulating computed goto
On Wednesday, 25 November 2020 at 20:05:28 UTC, NonNull wrote: So to simulate computed goto have to 1. wrap switch(x) in a loop [ while(0) ] 2. inside each case recompute x (instead of jump to computed y) 3. jump back to execute switch again [ continue ] It does look as if a nested switch can contain case labels from an outer switch which is very good. Did not try this out. Any more ideas, advice? I quess you could define a string or a template mixin to automate this, if there are many functions doing this. Then again, you probably should NOT have many functions working this way -it is not at all a scalable way to program. It might be good for something that is called very often and thus needs to be fast, but not for regular code. Computed `goto`s are even worse in maintainability than normal `goto`s.
Re: Simulating computed goto
On Wednesday, 25 November 2020 at 18:44:52 UTC, NonNull wrote: Is there a good way to simulate computed goto in D? I haven't used assembly myself, but it's possible that you can define a mixin that does this, using inline assembly.
Re: Vibe.D TLS problem
On Tuesday, 27 October 2020 at 17:36:53 UTC, Dukc wrote: ``` HTTP connection handler has thrown: Accepting SSL tunnel: error:1408F09C:SSL routines:ssl3_get_record:http request (336130204) ``` I figured out from the Vibe.D source code that if I enable the debug level of the console logger, I should get more info. How do I do that (dub project, main controlled by Vibe.D)?
Re: How kill executables started with spawnShell or executeShell when program finish?
On Tuesday, 27 October 2020 at 15:16:33 UTC, Marcone wrote: Becouse my program use plink.exe running with spawnShell or executeShell. But when my program finish with some crash, or killed with windows task manager by user, Plink still running. How can I stop all process initialized with spawnShell or executeShell when program finish? I another works, how can I make plink.exe only lives when program is running? This is a bit heavyweight, but should be doable: have your primary process to start a watchdog process for itself. The watchdog continuosly sends messages to the primary process. If the message gets blocked or the watchdog receives no answer, it assumes the primary process has stopped working and thus terminates first plink.exe first and then itself. In fact, while you're on it you can make the watchdog to terminate the primary process too, so the user won't have to kill the program manually in case of infinite loop.
Vibe.D TLS problem
I have a Vibe.D server binary that, locally at least, works. But
only without TLS. I want to add TLS to it and test it locally
with a self-signed certificate. I made one with LibreSSL, stored
in `cert.crt` and `key.key`. The application main function:
```
shared static this()
{ import vibe.d;
//the program does check the key files are there before
starting to listen
foreach(fileCheck;
[ tuple("salasanatiivisteet", "generoi salasanojen
tarkistuslista ennen palvelimen käynnistämistä,
salasanageneraattorilla"),
tuple("key.key", "TLS-avain puuttuu. Sen pitäisi olla
nimeltään key.key"),
tuple("cert.crt", "TLS-sertifikaatti puuttuu. Sen pitäisi
olla nimeltään cert.crt"),
])
if (!fileCheck[0].exists || !fileCheck[0].isFile)
{ fileCheck[1].logInfo;
return;
}
auto settings = new HTTPServerSettings;
enum portNumber = 8080;
settings.port = portNumber;
settings.bindAddresses = ["::1", "127.0.0.1"];
settings.sessionStore = new MemorySessionStore;
// these three lines added
settings.tlsContext = createTLSContext(TLSContextKind.server);
settings.tlsContext.useCertificateChainFile("cert.crt");
settings.tlsContext.usePrivateKeyFile("key.key");
// inrelevant stuff...
listenHTTP(settings, router);
}
```
It compiles and starts to listen just like normal, but when
trying to enter the localhost URL, the browser announces "the
connection was reset" and this is logged ten times in the server
side:
```
HTTP connection handler has thrown: Accepting SSL tunnel:
error:1408F09C:SSL routines:ssl3_get_record:http request
(336130204)
```
The server then resumes listening, printing another ten errors if
trying to re-enter the page. Linked openssl.sa is 1.1.1g (the
original, not LibreSSL). Relevant DUB package configuration:
```
"dependencies": {
"vibe-d": "~>0.9.2",
"vibe-d:tls": "*"
},
"subConfigurations": {"vibe-d:tls": "openssl-1.1"},
"versions": [ "VibeHighEventPriority" ],
"versions": [ "VibeDefaultMain" ]
```
Re: Memory management
On Tuesday, 29 September 2020 at 10:57:07 UTC, novice3 wrote: Naive newbie question: Can we have (in theory) in D lang memory management like V lang? I don't know V so can't be sure, but doing it the same way as in the examples sounds possible. The first two calls are easy. D string literals are stored in the read-only memory that is uploaded together with the machine code before execution. So the naive implementation wouldn't allocate any more than the V version. The third one is more difficult. To allocate without using GC or RC means using an owning container, that releases memory when exiting the scope. While they can be checked against leaking referenced using the `-dip1000` feature, it's practical only when the memory has a single clear owner and there is no need to store references to it elsewhere. The GC and RC are better as a general-purpose solution. On the other hand, D could avoid all allocation in the third example by using ranges. That would cause the printing function to figure out the message as it prints.
Re: Accessing non-binary Unicode properties with std.uni
On Monday, 28 September 2020 at 18:23:43 UTC, Chloé Kekoa wrote: The documentation of std.uni [1] says that the unicode struct provides sets for several binary properties. I am looking for a way to query non-binary properties of a character. Is that possible with std.uni or do I need to use a third-party library? I am specifically interested in the East_Asian_Width property [2] (which has six allowed values). Trying to access std.uni.unicode.East_Asian_Width results in the error message: No unicode set by name East_Asian_Width was found. [1]: https://dlang.org/library/std/uni.html [2]: https://www.unicode.org/reports/tr11/tr11-38.html It seems the East Asian width is Unicode standard 13.0, while Phobos implements 6.2. So seems like ca case for a third-party library :(.
Re: Good way to send/receive UDP packets?
On Wednesday, 22 July 2020 at 13:17:11 UTC, wjoe wrote: - Choosing a port which isn't in use right now isn't good enough because a few minutes later there may be another program using it, too, and for the same reason. But doesn't the UDP header include the sender IP address? So together with the magic number, shouldn't it be good enough? I know it definitely is not going to hold against jamming or a man in the middle, but it isn't supposed to, at this stage. It's used only for simulations that have the criticality of a casual Tetris server. I do acknowledge that the needs may rise later on. And if so, I understand that I'm much better off switching the protocol than trying to hardening the UDP.
Re: Good way to send/receive UDP packets?
Thank you everybody - Especially for the links to the blogs. This is just the kind of stuff I seek (didn't give a close look yet, though). I think I'm going to try std.socket first, since it's in the standard library. If it feels like it could be easier, I'll consider Libasync.
Re: My RPN calculator code review?
On Friday, 17 July 2020 at 21:37:46 UTC, AB wrote: I'd appreciate your opinions regarding style, mistakes/code smell/bad practice. Thank you. In a project this small, implementability (meaning, ease of writing) is really the main guideline, readability is a non-issue. When your codebase hits a few hundred lines in size you should start to gradually pay more attention to readability/scalablity. In fact, things that are recommended in 2000-line projects may even be antipatterns in 100-line projects. For example, unit testing greatly reduces bugs, so it's highly recommended in general. But if your project is so small that normal manual testing covers most everything anyway, unit testing is just needless bloat. A github gist might be better when doing style reviews, because the forum snippets tend to have wandering indentation and line wrapping.
Good way to send/receive UDP packets?
I have a project where I need to take and send UDP packets over the Internet. Only raw UDP - my application uses packets directly, with their starting `[0x5a, packet.length.to!ubyte]` included. And only communication with a single address, no need to communicate with multiple clients concurrently. I understand that I could do it either with the Curl library bundled with Phobos, or use Vibe.D or Hunt instead. But it's the first time I'm dealing with low-level networking like this, and my knowledge about it is lacking. So seek opinions about what library I should use, and more importantly, why. Other advice about projects like this is also welcome, should anyone wish to share it.
Re: Arduino and MCU Support
On Thursday, 25 June 2020 at 03:00:04 UTC, Dylan Graham wrote: I'm currently making an automatic transmission controller with Arduino. C++ just has too many traps that I keep falling into. Since stability is critical (if the code screws up at 100km/h I'm dead), I'd rather use a sane language like D. No, don't! Regardless of the language, you should never trust your safety on one single program. See https://www.digitalmars.com/articles/b39.html Realistically, doing such a controller cannot be one man/woman endeavour.
Re: "if not" condition check (for data validation)
On Thursday, 18 June 2020 at 12:50:35 UTC, Stanislav Blinov wrote:
auto not(alias cond)() { return !cond(); }
if (not!(() => abra && cadabra)) ...
but that is indeed even less readable.
No reason to use templates here
```
pragma(inline, true) auto not(bool cond) { return !cond(); }
if (not!(abra && cadabra)) ...
//same as above
if (abra.not || cadabra.not) ...
```
Re: "if not" condition check (for data validation)
On Thursday, 18 June 2020 at 13:57:39 UTC, Dukc wrote: if (not!(abra && cadabra)) ... if (not(abra && cadabra)) ...
Re: unit test that show more than one failure
On Tuesday, 16 June 2020 at 06:19:51 UTC, Joel wrote:
I've tired different unit test libraries, but they jump out on
errors instead of just adding to failed numbers.
I'm thinking like this:
```
@("dummy");
unittset {
0.shouldEqual(0);
1.shouldEqual(2);
2.shouldEqual(3);
}
```
Test: dummy
test passed line 10: 0 is equal to 0
test failed line 11: 1 is not equal to 2
test failed line 12: 2 is not equal to 3
1 passed
2 failed
The unit tests I tried would jump out on the first failure.
I have solved this. In my project, I have two modules like this:
```
module assertions;
auto assert_(A)(A canditate)
{ assert(canditate);
}
auto assertOp(alias pred, A)(A canditate)
if (is(typeof(cast(bool) pred(canditate
{ assert(pred(canditate));
}
auto assertOp(alias pred, A, B)(A canditate, B check)
if (is(typeof(cast(bool) pred(canditate, check
{ assert(pred(canditate, check));
}
auto assertEmpty(A)(A aEl)
{ assertOp!(a => a.empty)(aEl);
}
auto assertEqual(A, B)(A aEl, B bEl)
{ assertOp!((a,b) => a == b)(aEl, bEl);
}
auto assertClose(A, B)(A aEl, B bEl)
{ import std.math;
assertOp!((a,b) => a.isClose(b))(aEl, bEl);
}
```
```
module assertions.characterization;
auto assert_(A)(A canditate)
{ import std.stdio : writeln;
writeln(canditate, cast(bool) canditate? " (passes)": "
(fails)");
}
auto assertOp(alias pred, A)(A canditate)
if (is(typeof(cast(bool) pred(canditate
{ import std.stdio : writeln;
writeln(canditate, cast(bool) pred(canditate)? " (passes)": "
(fails)");
}
auto assertOp(alias pred, A, B)(A canditate, B check)
if (is(typeof(cast(bool) pred(canditate, check
{ import std.stdio : writeln;
writeln(canditate, cast(bool) pred(canditate, check)? "
(passes)": " (fails)");
}
auto assertEmpty(A)(A aEl)
{ assertOp!(a => a.empty)(aEl);
}
auto assertEqual(A, B)(A aEl, B bEl)
{ assertOp!((a,b) => a == b)(aEl, bEl);
}
auto assertClose(A, B)(A aEl, B bEl)
{ import std.math;
assertOp!((a,b) => a.isClose(b))(aEl, bEl);
}
```
So I usually have the test like this:
```
@safe unittest
{ import assertions;
0.assertEqual(0);
1.assertEqual(2);
2.assertEqual(3);
}
```
...but when it fails, I just change the import to
`assertions.characterization`, and all test results, along with
info whether they're correct, are printed.
Re: Windows + LDC/DMD installation nightmare when changing VS versions
On Friday, 12 June 2020 at 15:21:12 UTC, Guillaume Piolat wrote: Any idea what could be causing this? Please help. This was a living nightmare. I just want a working setup... I don't know if this is any help, as I don't use Visual Studio myself, but: You're trying to build for a 32-bit architechture, but the DUB receives `--arch=x86_64`. It should be receiving `--arch=x86`. It's likely that due to this it builds a 64-bit binary and then fails to link into something that was correctly built as 32-bit.
Re: Why is there no range iteration with index by the language?
On Wednesday, 10 June 2020 at 15:34:57 UTC, Steven Schveighoffer wrote: My biggest problem with enumerate is that you can't bind the tuple to parameters for something like map: arr.enumerate.map!((idx, val) => ...) doesn't work. Instead you have to do: arr.enumerate.map!((tup) => ...) And use tup[0] and tup[1]. -Steve ``` alias tupArg(alias func) = x => func(x.expand); arr.enumerate.map!(tupArg!((idx, val) => ...)) ``` Somewhat heavy on syntax, but better than `tup[0]` or `tup[1]` IMO.
Re: how to append (ref) int[] to int[][]?
On Monday, 8 June 2020 at 06:13:36 UTC, mw wrote:
what I really want in (a) is append `ref arr` and output [[3],
[3], [3]], i.e. the real `arr` be appended instead of its copy.
I tried to change arrs' decl to:
(ref (int[]))[] arrs; // the intended semantics I want
1) I'm wondering how to achieve what I want? and
2) why "~=" here will append a copy rather than the real `arr`
itself to arrs?
Thanks.
```
import std.stdio;
void f(ref int[] arr) {
arr ~= 3;
}
void main() {
import std.algorithm;
int[]*[] arrs;
int[]* arr;
foreach (i; 0 .. 3) {
//stack allocated array pointer would expire on end of
scope, so must allocate the them on heap since we're keeping
refeerences on them.
auto arrayAllocation = new int[][1];
arr = [0];
*arr = new int[0];
arrs ~= arr;
f(*arr);
}
//will print an array of addresses otherwise
arrs.map!(ptr => *ptr).writeln;
}
```
But I must say I would generally prefer just calling `f()` on
`arrs[i]` directly after appending, or calling the function
before appending. One reason is that needless heap usage is
generally less efficient than using the stack.
Re: Distinguish between a null array and an empty array
On Sunday, 24 May 2020 at 12:29:23 UTC, bauss wrote: Dang, that sucks there is no proper way and I would say that's a big flaw of D. Because what I need it for is for some data serialization but if the value is an empty array then it should be present and if it's null then it should not be present. Since null is used to say "ignore this" in the data serialization. Oh well. If you want to avoid the memory cost of `Nullable`, I think you could still have a special value for "no data". But I wouldn't use D `null` for it, because it's so common for it to be used for empty values. Instead, I'd define a small data section somewhere. You test whether the array points to it (`[0] == [0]`), and if, it means no data.
Re: redirect std out to a string?
On Thursday, 21 May 2020 at 04:29:30 UTC, Kaitlyn Emmons wrote: is there a way to redirect std out to a string or a buffer without using a temp file? If you want to do the redirection at startup, it's possible. Have an another program to start your program by std.process functions and redirect stdout to a pipe. The outer program can then handle the output of the inner program however it wishes. Clumsy but possible. But I don't know whether a process can redirect it's own standard input or output.
Re: How to use this forum ?
On Wednesday, 20 May 2020 at 20:49:52 UTC, Vinod K Chandran wrote:
Hi all,
I have some questions about this forum.
1. How to edit a post ?
No can do :(. Well, moderators can delete posts so you could try
to ask them nicely in some cases but the primary way tends to be
the same as with email: send a correction message.
And if I recall correctly, this forum is based on some email
system, so even if a moderator deletes something, it'll probably
only be hidden from those that talk via forum.dlang.org - not
from those that use their email.
2. How to edit a reply ?
Same as above.
3. How to add some code(mostly D code) in posts & replies.
Matter of taste. I personally tend to do it like this:
```
void main()
{ import std.stdio;
writeln("hello world!");
}
```
Another good way is to use https://run.dlang.io/ and export your
code as gist from there.
4. How to add an image in posts & replies.
Add it somewhere else and post a link to it.
5. Is there a feature to mark my post as "[SOLVED]" ?
Alas, no.
Re: Why emsi containers have @disabled this(this) ?
On Tuesday, 19 May 2020 at 20:51:01 UTC, Luis wrote: I saw that they have postblit operator... But i don't understand exactly why. In special, when they implement InputRange over the containers, but having disabled postblit, make nearly useless (at least as I see on this old post https://forum.dlang.org/thread/n1sutu$1ugm$1...@digitalmars.com?page=1 ) You have to understand the memory management difference between EMSI-containers and regular D slices. A normal slice won't worry about freeing the memory used. It just assumes that either the garbage collector will take care of it (the usual case), or that the code will tell manually when the memory really needs to be freed (possibly by some other reference to the same memory). EMSI-containers, however, are designed to free their memory after use themselves. They do it by the Resource Acquisition Is Initialization principle: when the container gets deleted, the underlying data gets freed right away. This leads to that there must be only one container using the same memory. It would not do to make a copy of it, unless it's a deep copy (Deep copy means that also the underlying memory is copied. It tends to take long.). This is the reason that postblits are disabled in EMSI-containers. It wants to protect you from accidents. If you want to store the same container in many places, store references to it instead. And when iterating over it, you get the underlying range first, like Mike said. The underlying range can likely be copied freely.
Re: variant visit not pure?
On Thursday, 7 May 2020 at 20:12:03 UTC, learner wrote: Modules of D standard library aren't in a good shape, if everyone suggests alternatives for a basic building block as variant. I don't think Variant as a whole is the problem, when one uses it as the infinite variant it does fairly much what one can expect. The finite-field specialization of it is the one that's badly implemented. The types VariantN can hold are known at compile time, why can't it be specialized? It could, probably. This shows the biggest weakness (and strength) of D development: It's voluntary, so people work on that they happen to want to. That makes it unevenly developed compared to financially backed projects. We have both plenty of cool & rare features and lack of many relatively basic ones at the same time.
Re: variant visit not pure?
On Thursday, 7 May 2020 at 15:36:36 UTC, Ben Jones wrote: I've been using SumType... What are the main differences between it and TaggedAlgebraic? I have not used the the algebraic type of Taggedalgebraic tbh, but it also has a tagged union type that I have good experiences with. Unlike Phobos algebraic or SumType, it can have multiple fields of same type that are still separate by the tag value. Also unlike the two others I mentioned, you can handily define a `Void` field (or many of them) if you want special values for the tag that don't come with a value. In essence, `Taggedalgebraic.TaggedUnion` it's the D equivalent of Rust `enum`[1]. 1: https://doc.rust-lang.org/book/ch06-00-enums.html
Re: variant visit not pure?
On Thursday, 7 May 2020 at 10:21:26 UTC, Dukc wrote: that's the reason why `std.range.enumerate` does not infer attributes for example This was wrong. `enumerate` can infer. It's `lockstep` that cannot.
Re: variant visit not pure?
On Thursday, 7 May 2020 at 13:17:21 UTC, learner wrote: I've find this: https://issues.dlang.org/show_bug.cgi?id=16662 Hmm, that explains why it can't infer attributes. An unlimited variant could contain an object, and using it might or might not be . Of course, it could still infer the attribute for algebraic types were the wrapper a bit smarter. But `Algebraic` is inferior to the DUB packages anyway. Bad performance like Simen said, and can always be `null` regardless of requested types. With Taggedalgebraic, you can insert `Void` to allowed types if you want `null` value but you don't have it just because.
Re: Is there a way to benchmark/profile portably?
On Thursday, 7 May 2020 at 10:51:27 UTC, Simen Kjærås wrote: If I understand correctly, you want to measure how many cycles pass, rather than clock time? Something like that. Well, I would also like to eliminate differences based on different memory caches between machines. In addition, if the profiler could eliminate the randomness of the benchamrks that results from memory aligment, context switches and dunno, that would obviously be a big plus for automatic testing. If so, it seems perf can do that: https://perf.wiki.kernel.org/index.php/Tutorial Sounds worth a look. Thanks!
Re: Is there a way to benchmark/profile portably?
On Thursday, 7 May 2020 at 11:06:17 UTC, Dennis wrote: You can make a reference program that you use to get a measure for how fast the computer is that you run the benchmark on. Then you can use that to scale your actual benchmark results. When testing regressions there's a fairly obvious choice for this reference program: the old version. You can compare those results with the new version and report the relative difference. I have to keep that in mind, but I'd prefer something that does not require keeping old sources working, or floating their binaries around.
Re: variant visit not pure?
On Thursday, 7 May 2020 at 09:22:28 UTC, learner wrote: Good morning, Is there a reason why std.variant.visit is not inferring pure? I think `variant` will not infer any trributes. I'm not sure why. It could be some language limitation (that's the reason why `std.range.enumerate` does not infer attributes for example). Or it could be just badly implemented. Either way, there are DUB packages that are better in this (and other) regards. I recommend Taggedalgebraic[1]. [1] https://code.dlang.org/packages/taggedalgebraic
Is there a way to benchmark/profile portably?
Is there some way to measure the performance of a function so that the results will be same in different computers (all x86, but otherwise different processors)? I'm thinking of making a test suite that could find performance regressions automatically. I figured out Bochs[1] could be used for that, but it seems an overkill for me to install a whole virtual operating system just to benchmark functions. Does anybody know more lightweight way? [1] http://bochs.sourceforge.net/
Re: How to get Code.dlang.org to update the package?
On Wednesday, 12 February 2020 at 13:05:00 UTC, Petar Kirov [ZombineDev] wrote: On Wednesday, 12 February 2020 at 12:42:32 UTC, Dukc wrote: I have pushed a new release tag in Github around two weeks ago, and ordered a manual update at DUB, yet DUB has still not aknowledged the new tag. Is there some requirement for the release tag for it to be recognized? Hi Dukc, I'm not sure which dub package you're referring to, but I'm gonna guess that it's this one: http://code.dlang.org/packages/nuklearbrowser, which corresponds to this github repo: https://github.com/dukc/nuklearbrowser. Correct I think the problem is that your latest tag is 0.0.2, instead of v0.0.2 (https://github.com/dukc/nuklearbrowser/tags). I hope this helps! Cheers, Petar Certainly does, thank you.
How to get Code.dlang.org to update the package?
I have pushed a new release tag in Github around two weeks ago, and ordered a manual update at DUB, yet DUB has still not aknowledged the new tag. Is there some requirement for the release tag for it to be recognized?
Re: How to set up multi-dimensional DUB package configuration?
Illustration, I want to choose both an edition and marked
copyright holder:
```
configuration "inhouse" {
targetType "executable"
versions "InhouseEdition"
}
configuration "salesmen" {
targetType "executable"
versions "SalesmenEdition"
}
configuration "internet" {
targetType "executable"
versions "InternetEdition"
}
configuration "copyrightcompanya" {
versions "CopyrightCompanyA"
}
configuration "copyrightcompanyb" {
versions "CopyrightCompanyB"
}
```
How to set up multi-dimensional DUB package configuration?
My application has two copyright holders, so I want to be able to specify in the build command whose copyright marks get compiled to the program. D part of the application is built by DUB. DUB configurations would do the trick, but they are already used to define different editions of the application. I have to be able to choose the edition indepently of the copyright holder. I don't necessarily need two-dimensional configuration. If there a way to order DUB to define an extra D version without altering `dub.sdl` to do that, it would suffice. But is there?
Re: why local variables cannot be ref?
On Monday, 25 November 2019 at 03:07:08 UTC, Fanda Vacek wrote:
Is this preferred design pattern?
```
int main()
{
int a = 1;
//ref int b = a; // Error: variable `tst_ref.main.b` only
parameters or `foreach` declarations can be `ref`
ref int b() { return a; }
b = 2;
assert(a == 2);
return 0;
}
```
Fanda
It's okay, but I'd prefer an alias, because your snippet uses the
heap needlessly (it puts variable a into heap to make sure there
will be no stack corruption if you pass a pointer to function b()
outside the main() function)
Re: Troubleshooting DUB invocations
On Tuesday, 19 November 2019 at 13:41:32 UTC, Sebastiaan Koppe wrote: A @disabled function stub would serve better, unless I'm missing something. Either way, as long as there is a clear way to debug why it ended up there. Unlike what we have now where you need to dig endlessly. But the @disabled function stub (if my thinking is sound) would have the advantage that it'd prevent compilation only if called -not if only imported.
Re: Troubleshooting DUB invocations
On Monday, 18 November 2019 at 19:35:13 UTC, Sebastiaan Koppe wrote: Kinke made some changes in dub to facilitate separate linking for ldc. I am not aware of all the details but the major benefit is that it allows cross compilation with dub and ldc. Yeah, definitely useful if you want to link in, say, a C-borne wasm binary. Because of the separate linking the --no-as-needed turned up. As far as I can see it is only needed when compiling for linux. Which brings up the question, why linux? Aren't we compiling for wasm? Well yes. But that is just the way things worked up until now, ldc and dub just pick the host machine. Luckily there is the new dub `--arch` argument that can take a llvm triple, in our case wasm32-unknown-unknown-wasm. This causes dub not to add the `--no-as-needed`. That was news to me - I thought everything was always being compiled to WASM. Except, that it also passes the triple upwards the dependency tree. Now all the dependencies of spasm get compiled targeting wasm. This is a good thing, except that the optional package which spasm depends on fails to compile with it. There is a newer version that fixes the configuration, but that one fails because of the `from.std` import idiom (it imports the std package from phobos which doesn't recognise wasm and fails with "Unknown OS"). I have sometimes thought that perhaps a static assert isn't the best thing to use for unimplemented features in Phobos, precisely because of this issue. A @disabled function stub would serve better, unless I'm missing something. In the meantime I am going to make a PR for the optional package to avoid the `from.std` idiom. Although I might end up playing whack-a-mole here, as there might be more dependencies that need a fix now. "ending up"? If it's like what getting Phobos to work has been for me, you're continuing the game, not ending up playing it ;D. Another workaround that you can use right now is by adding the `--build-mode=allAtOnce` argument to dub. It effectively gets you the old behaviour. It is what I am using in my CI to get it to go green again. Do not hurry more than you want -I already got my extract-dub-failure workaround working.
Re: Troubleshooting DUB invocations
On Wednesday, 13 November 2019 at 15:41:01 UTC, Sebastiaan Koppe wrote: It has been on the back of my mind since 1.18-beta came out. I am going to reserve a little time tomorrow to work on it. Regarding that, perhaps I can save you a bit trouble if you also try to get 1.19 working: if you get compile errors related to SortedRange, the fix is https://github.com/dlang/phobos/pull/7266.
Re: Should I stop being interested in D language if I don't like to see template instantiation in my code?
On Wednesday, 13 November 2019 at 14:59:57 UTC, Dukc wrote: 4: Templates. Same code size bloat as with options 1 and 3, Meant binary size bloat
Re: Why same pointer type for GC and manual memory?
On Wednesday, 13 November 2019 at 11:07:12 UTC, IGotD- wrote: I'm trying to find the rationale why GC pointers (should be names managed pointers) are using the exact same type as any other pointer. Doesn't this limit the ability to change the default GC type? What does grabage collector type mean? Doesn't this confusion make GC pointers just as unsafe as raw pointers? It does if you pass the pointers to somewhere the garbage collector does not know about. However, normally it has a list of all memory used by the program -even the memory that is not managed by it. But if you, for example, put a pointer to memory allocated by some C program that is totally unaware of the GC, you need to either manually register (and unregister) the memory to the GC, or keep a copy of the pointer in somewhere the GC knows about. Assuming the pointed memory is controlled by GC, that is. Otherwise, the GC will not find the pointer during collection and think you have stopped using the memory it points to. Has there been any prior discussion about introducing managed pointers in D? I'm not 100% sure what managed pointers mean -Are they so that you can't pass them to unregistered memory? A library solution would likely do -wrap the pointer in a struct and make it @system to extract it's pointer as "raw". So you cannot put it to C-allocated arrays without type casting, which you probably don't do accidently.
Re: Troubleshooting DUB invocations
On Tuesday, 12 November 2019 at 18:32:32 UTC, kinke wrote: Dub is open-source, so you can grep the source. - Dub uses it for all 3 compilers (e.g., https://github.com/dlang/dub/blob/f87302dd206b0e5871b39704e694b2194e294aa5/source/dub/compilers/ldc.d#L249), and I'm not sure it's really needed. Anyway, you can also use another linker that supports this flag (e.g., via `-linker=gold`). Thanks. At first it didn't seem to work. Then I realized that the `--link-internally` flag that's specified in `ldc.conf` prevents changing the linker. Took it off, and the gold linker understood the flag in question, but had problems with others. I tried removing some, but there were still more to remove. Getting WASM code to link tends to be trial and error in my experience, so I decided best not to stray far from what Spasm does. I also tried LDC 1.18, but the dub also added that unwanted flag here. I don't wan't to use older LDC than that. However, extracting the LDC invocation and manually calling it without `--no-as-needed` appears to work. Solution? I'm going to write my `build.d` to do just that automatically. Is there an issue about that already, or should I open one?
Re: Should I stop being interested in D language if I don't like to see template instantiation in my code?
On Wednesday, 13 November 2019 at 14:01:13 UTC, BoQsc wrote: I don't like to see exclamation marks in my code in as weird syntax as these ones: to!ushort(args[1]) s.formattedRead!"%s!%s:%s"(a, b, c); No pressure to use templates. D is designed to be multi-paradigm, and in many was combines the advantages of c++ and c# even if you use just traditional imperative or object oriented ways. For example, C# has array bounds checking, C++ has raw type casting, but D has both. And neither of the mentioned languages have `scope (exit`. Granted, some other new language, like Go, might be even better if you don't care about templates. That being said, I think you definitely should learn about templates. First, it let's you understand code written by others, and secondly you can evaluate whether you really want to code without them. There are problems you simply cannot deal with as efficiently as you can with templates. For example, if you write a math function you want to work with both integers and floats, you basically have four options: 1: Code duplication. 2: Runtime casting of the argument to the type the function is implemented in, wasting computational power. Traditional object-oriented solution falls in this category. 3: Using a macro preprocessor. Macros are unaware of code semantics and thus are known for making codebases buggy and hard to maintain. 4: Templates. Same code size bloat as with options 1 and 3, but otherwise basically no downsides.
Troubleshooting DUB invocations
When trying to compile a project including newest Spasm (DUB package) using the newest LDC via DUB, the result is: ``` lld: error: unknown argument: --no-as-needed ``` I then ran DUB with -v switch and it turned out the invocation contained `-L--no-as-needed` as first of all the -L arguments. The trouble is, how do I know what causes DUB to add that argument to the invocation? I could find no reason in `dub.` files of either my package, Spasm or any package in Spasm dependency tree.
Re: Good way let low-skill people edit CSV files with predefined row names?
On Friday, 25 October 2019 at 21:58:27 UTC, Laeeth Isharc wrote: Another Symmetry project allows reading Excel files and a third is wrapper and bindings around a C library to write Excel files. We use them in production daily though there may be rough edges for features we don't use. I should think you can use a Javascript library and call it from D. See trading views repo by Sebastian Koppe for an example of this. Bindings are manual currently but he will work on generating them from the Typescript bindings in time. Sorry for late reply. I was told that I can do this by writing the key field only as a comment (so changing it will do no harm - the real key would be dictated either by an ID number or simply row index). In the case they want me to do it without writing my own GUI, I'm going to consider the DUB solutions first but look at what you said if I still miss something. Thank you.
Re: Good way let low-skill people edit CSV files with predefined row names?
On Thursday, 24 October 2019 at 16:50:17 UTC, Dukc wrote: Hmm, I need to check whether I can do that on LibreOffice Calc. Unfortunately, no. If there's a way to do that, it's not obvious. I should be able to make an easy-to-use excel-to-csv translator using Atilas Excel utilites without too much effort. This was wrong: Atila's Excel-d enables writing plugin functions, but not reading the spreadsheets. There are other DUB utilities for that, though. I quess I will give my employer two options: Either the price variables are in an one-column CSV and I distribute the key column separately so they don't mess it up, or I take my time to do a GUI solution. Unless somebody has better ideas?
Re: Good way let low-skill people edit CSV files with predefined row names?
On Thursday, 24 October 2019 at 16:20:50 UTC, jmh530 wrote: If they are only opening it in Excel, then you can lock cells. You should be able to do that with VBA. At least I know it works with xlsx files. Not sure on csv now that I think on it. Hmm, I need to check whether I can do that on LibreOffice Calc. I do not to rely on Ms Excel -in part because I don't have one myself! But if the answer is positive, it might be worth considering. I should be able to make an easy-to-use excel-to-csv translator using Atilas Excel utilites without too much effort.
Good way let low-skill people edit CSV files with predefined row names?
We're planning to have our product preview program to calculate and suggest a price for the product displayed. There are a lot of variables to take into account, so it's essential the users can edit the price variables themselves. The problem is that many of them are not the best computer users around, even by non-programmer standards. I'd like the price variable file to be in CSV format, so I don't have to go looking for a new file parser (the preview program is mostly compiled to JavaScript from C# with some D (spasm) and native JavaScript in the mix). I know I can tell the users to use spreadsheet programs to edit CSV, but they are still going to get the variable field names wrong, and I do not want that. Another option would be for me to write an editor for them specially for this purpose. The editor would not have to be embeddable into a browser, so I could write it in D. But it'd have to use a GUI, which would likely take a relatively long time to develop, and thus costly for my employer. Does anybody know a program/file format that could enable editing the fields while guarding against formatting/field naming errors? Even if it isn't CSV, it is going to be easier for me to write a translator than a GUI editor.
Re: Good way let low-skill people edit CSV files with predefined row names?
On Thursday, 24 October 2019 at 16:03:26 UTC, Dukc wrote: Even if it isn't CSV, it is going to be easier for me to write a translator than a GUI editor. Assuming the file format is simple, of course
Re: Pro programmer
On Sunday, 25 August 2019 at 21:30:10 UTC, GreatSam4sure wrote: I am wondering as to what is the starting point of being a pro programmer. If I want to be a pro programmer what language must I start with? Any general purpose language will do. Basically everything can be expressed in any language, through some tasks are very cumbersome in tasks they are not designed for. Most pro programmer I have heard of are all C and C++ Guru. Most of the best guys on this D forum falls into that category. C and C++ have steep learning curves, and tend to be better for professionals than amateurs. That does not mean C/C++ usage is what defines a pro. Even php, famous for being simple to learn but often hated by professionals, can be used professionally. I really want to know programming to the core not just tied to a language or just at the level of drag and drop or use a framework or library. Don't worry, learn to apply one language in practice and you'll usually figure out automatically how to apply any language you will learn. Well, sometimes when you transition to a new language you should learn new ways to do thing, because the new language is better suited for those than your old language. Famous example is that C programmers that transitioned to C++ or Java in the 90's were encouraged to start to thinking in object oriented manner. They did not strictly have to, as C++ and Java can be used for same programming stye as C, and C can do sort-of object-oriented programming, but object-oriented designs were (and are) so much easier to implement in the newer languages that in practice, object design should be used a lot more now than in the 70's. I will appreciate your help in this matter. I am ready to put in hard work. I ready know a little of java, actionscrip 3.0, kotlin, D but at the surface level but can use them to write app. But I am concern with matter like how can I write a GUI toolkit from the ground up. Basically, GUI libraries call the operating system API that is different for different operating systems.
Re: /usr/bin/ld.gold: error: failed to find object -lz
On Thursday, 15 August 2019 at 12:02:00 UTC, kinke wrote: That's the library you need. You may have messed things up by installing a non-dev package from Fedora (!). Fortunately it's written in red at YAST, because it's not from the official repos. I can easily find it to get rid of it when I want.
Re: /usr/bin/ld.gold: error: failed to find object -lz
Investigated this matter further. The most likely reason seems to be that the required library -zlib- (Yes, ld.gold was getting the arguments in correct form despite what I said. Sorry.) is installed only in dynamic form (.so), but ld.gold finds only static libraries (.a). Not 100% sure yet, because it wasn't worth the time to convert the libraries/get the linker to work with dynlibs right now, but this seems to be the cause.
Re: How to run the dub bundle with dmd
On Saturday, 10 August 2019 at 13:18:19 UTC, greatsam4sure wrote: I came across the problem recently. I have dub 1.11.0 install on my windows 10 core i7 but does not support the command "dub add package name" since all the packages in dub package register now use this command. I cannot find window binary for the recent version of dub What did you precisely write on the console, and what was the output? I have uninstalled the dub 1.11.0 on my machine, I have to use the one bundled with DMD 2.087.1. If I run dub -version, windows 10 throw an error that says " this app can run on this machine". That means that either you installed wrong dub (linux version for example), or the executable file is corrupt. Download a new one.
Re: LNK4255 warning - should I be concerned?
On Thursday, 8 August 2019 at 18:14:22 UTC, DanielG wrote: "warning LNK4255: library contain multiple objects of the same name; linking object as if no debug info" Is there some way to get more detail about this warning? Might help to know which objects ... My program is working fine now, but is this going to cause problems later on? Like when I want to debug? Let me guess, you're linking Vibe.D? I get those errors all the time while using it. Haven't noticed effect on behaviour but it might be related to why it won't compile as 32-bit.
Getting a HTTP request body over wire for Vibe.d to process
I am trying to use XMLHttpRequest[1] to send a request with a body for Vibe.D to process. However, it seems that I'm getting tripped up on serverside and client side api simultaenously, with no way to know what's really happening. I'm starting to be positive that I need a code example or I'll be trying to pass that HTTP body till Chrismas! Can anybody suggest an example, with both clientside and serverside code. I don't care anybody if the body is raw bytes or JSON, I just want to finally receive it. [1] https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest/send
Re: Module static constructor doesn't work?
On Thursday, 8 August 2019 at 14:55:37 UTC, Andrey Zherikov wrote:
I have the following code:
// lib1/lib.d
module lib;
import std.stdio;
static this()
{
writeln("+" ~ __FILE__);
}
static ~this()
{
writeln("-" ~ __FILE__);
}
// main.d
int main()
{
import std.stdio;
writeln("hello");
return 0;
}
So if I compile lib.d and main.d together then ctor/dtor are
called:
$ dmd.exe main.d lib1/lib.d && main.exe
+lib1\lib.d
hello
-lib1\lib.d
But if I create library from lib.d first and then link it with
main.d then ctor/dtor are not called:
$ dmd.exe -lib lib1/lib.d -od=lib1
$ dmd.exe main.d lib1/lib.lib && main.exe
hello
I'm looking only quickly without being sure about this, but I
suspect you are only linking in the binary of `lib.d`. If you do
that, you need to generate or define a header file for `lib.d`.
Probably a better idea is to just use the first compiler
invocation. It should generate an object file of `lib.d` that is
only recompiled if you change source code of `lib.d`.
If for some reason you need a `.lib` file, I think you want to
still include `lib.d`. The compiler needs it to know how to use
the pregenerated binary, including calling those module
constructors you described.
But take this with a grain of salt, because I haven't done that
before and don't know the details.
Re: /usr/bin/ld.gold: error: failed to find object -lz
Taking the LDC2 invocation and removing `-lz` and `-lresolv` seems to work around the problem. A bad long-term solution though.
Re: /usr/bin/ld.gold: error: failed to find object -lz
On Wednesday, 7 August 2019 at 02:47:11 UTC, ?boing? wrote: On Tuesday, 6 August 2019 at 12:39:08 UTC, Dukc wrote: On Tuesday, 6 August 2019 at 11:41:25 UTC, kinke wrote: LDC definitely doesn't add that. zlib shouldn't be necessary, as Phobos contains an (IIRC, outdated) version of it. Anyway, you should be able to please the linker by installing a zlib package, such as `zlib1g` on Debian/Ubuntu. Installed a Fedora version from http://rpmfind.net/linux/rpm2html/search.php?query=zlib (using OpenSUSE, which uses .rpm:s like Fedora). No effect. https://software.opensuse.org/package/zlib-devel-static An error when installing, apparently internal. I doubt anyway if lack of zlib is the real cause, as the error message looks like it meant that it tries to look for "-lz" for linking it in the application.
Re: /usr/bin/ld.gold: error: failed to find object -lz
On Wednesday, 7 August 2019 at 02:47:11 UTC, ?boing? wrote: On Tuesday, 6 August 2019 at 12:39:08 UTC, Dukc wrote: On Tuesday, 6 August 2019 at 11:41:25 UTC, kinke wrote: LDC definitely doesn't add that. zlib shouldn't be necessary, as Phobos contains an (IIRC, outdated) version of it. Anyway, you should be able to please the linker by installing a zlib package, such as `zlib1g` on Debian/Ubuntu. Installed a Fedora version from http://rpmfind.net/linux/rpm2html/search.php?query=zlib (using OpenSUSE, which uses .rpm:s like Fedora). No effect. https://software.opensuse.org/package/zlib-devel-static An error when installing, apparently internal. I doubt anyway if lack of zlib is the real cause, as the error message looks like it meant that it tries to look for "-lz" for linking it in the application.
Re: /usr/bin/ld.gold: error: failed to find object -lz
On Tuesday, 6 August 2019 at 11:41:25 UTC, kinke wrote: LDC definitely doesn't add that. zlib shouldn't be necessary, as Phobos contains an (IIRC, outdated) version of it. Anyway, you should be able to please the linker by installing a zlib package, such as `zlib1g` on Debian/Ubuntu. Installed a Fedora version from http://rpmfind.net/linux/rpm2html/search.php?query=zlib (using OpenSUSE, which uses .rpm:s like Fedora). No effect.
Re: LDC won't find ld linker -why?
On Wednesday, 10 July 2019 at 23:15:38 UTC, Johan Engelen wrote: On Tuesday, 9 July 2019 at 15:25:17 UTC, Dukc wrote: I just downloaded ldc 1.15.0 for Linux from GH releases. Testing it, it will make the object file out of a hello world application, but then complain: ``` collect2: fatal error: cannot find ‘ld’ compilation terminated. ``` Run LDC with "-v" and check what the linker command is (somewhere at the bottom, LDC invokes `gcc` for linking). You might see something like `-Wl,-fuse-ld=...` in that gcc command line. Perhaps that ld.gold / ld.bfd is not installed and thus GCC complains that it cannot find it. See e.g. https://askubuntu.com/questions/798453/collect2-fatal-error-cannot-find-ld-compilation-terminated -Johan Thanks, that worked, I needed ld.gold. There was a catch, however: one would think that `llvm8-gold` is the .rpm package in question, but installing it did change nothing. Good that you provided that link, otherwise I would never have quessed that I have to install `binutils-gold` instead.
LDC won't find ld linker -why?
I just downloaded ldc 1.15.0 for Linux from GH releases. Testing it, it will make the object file out of a hello world application, but then complain: ``` collect2: fatal error: cannot find ‘ld’ compilation terminated. ``` This is strange, because running either `ld` or `clang` (yes, I checked readme file) in the same directory as the compilation will indicate that I have both of them. And clang is version 8, same as the llvm version that 1.15.0 is based on. dmd works correctly, but downloaded that as `.rpm`. If it makes any difference, I just dumped the contents of the ldc download folder directly into my home, so that there is `~/bin/ldc2`, `~/etc/ldc2.conf`, and so on. Making a symlink to ld into ~/bin won't make a difference, and `ln` won't let me to make a hard link, it complains about something like invalid link between devices (ln is in `usr/bin/` which should be on same drive and partition as `~/bin`). What could be wrong?
