Re: std.string.assumeUTF() silently casting mutable to immutable?

[RazvanN via Digitalmars-d-learn]

On Wednesday, 14 February 2024 at 11:56:29 UTC, Forest wrote:

On Wednesday, 14 February 2024 at 10:57:42 UTC, RazvanN wrote:


This has already been fixed, you just need to use 
-preview=fixImmutableConv. This was put behind a preview flag 
as it introduces a breaking change.


I just tried that flag on run.dlang.org, and although it fixes 
the case I posted earlier, it doesn't fix this one:


```d
string test(const(ubyte)[] arr)
{
import std.string;
return arr.assumeUTF;
}
```

Shouldn't this be rejected as well?


Indeed, that should be rejected as well, otherwise you can modify 
immutable table. This code currently happily compiles:


```d
string test(const(ubyte)[] arr)
{
import std.string;
return arr.assumeUTF;
}

void main()
{
import std.stdio;
ubyte[] arr = ['a', 'b', 'c'];
auto t = test(arr);
writeln(t);
arr[0] = 'x';
writeln(t);
}
```

And prints:

```
abc
xbc
```

However, this seems to be a different issue.

Re: Is it possible to do this with a template?

[RazvanN via Digitalmars-d-learn]

On Friday, 17 December 2021 at 07:52:18 UTC, rempas wrote:
I want to use an expression and put it in place inside the `if` 
parentheses. The expression is: `is(typeof(val) == type)`. I 
want to use a template called "is_same" that will take the 
value and a type to place them to the respective places. I have 
tried the following but it doesn't seem to work:


```
mixin template is_same(val, type) {
  is(typeof(val) == type)
}

void main() {
  int val = 10;
  static if (is_same!(val, int)) {}
}
```

When trying to compile, I'm taking the following error message:

```
Error: declaration expected, not `is`
```

Is this a limitation of templates in D or is there a way to 
bypass this?


There is also a compiler trait [1] which can do that for you:

```d
void main()
{
int val = 10;
static if (__traits(isSame, typeof(val), int)) {}
}
```


[1] https://dlang.org/spec/traits.html#isSame

Re: template ctor overload Segmentation fault

[RazvanN via Digitalmars-d-learn]

On Sunday, 12 December 2021 at 11:57:43 UTC, vit wrote:

Hello, why does this code fail to compile?

```d
struct Foo(T){
this(Rhs, this This)(scope Rhs rhs){
}

this(ref scope typeof(this) rhs){
}
}


struct Bar{
Foo!int foo;
}

void main(){
}
```

error: Segmentation fault (core dumped)


PR: https://github.com/dlang/dmd/pull/13427

Re: template ctor overload Segmentation fault

[RazvanN via Digitalmars-d-learn]

On Tuesday, 14 December 2021 at 13:02:16 UTC, Tejas wrote:

On Tuesday, 14 December 2021 at 12:04:36 UTC, RazvanN wrote:

[...]


Then why did my modification work?

```d
struct Foo(T){
this(Rhs, this This)(scope Rhs rhs){
}

this(scope Foo!(T)* rhs){ //replaced typeof(this) with 
Foo!T and ref with pointer. Code still works if I retain 
typeof(this)

}
}


struct Bar{
Foo!int foo;
}

void main(){
import std.stdio:writeln;

Bar bar = Bar();
auto BAR = new Bar();
writeln(bar, "\t", BAR, "\t", *BAR);
}
```

Did my modifications ensure that this is not treated as a copy 
constructor?


Yes, the copy constructor needs to be explicitly defined by 
passing a ref parameter. Since you are expecting an explicit 
pointer, the compiler does not see it as a copy constructor and 
therefore does not try to generate one for Bar.

Re: template ctor overload Segmentation fault

[RazvanN via Digitalmars-d-learn]

On Sunday, 12 December 2021 at 11:57:43 UTC, vit wrote:

Hello, why does this code fail to compile?

```d
struct Foo(T){
this(Rhs, this This)(scope Rhs rhs){
}

this(ref scope typeof(this) rhs){
}
}


struct Bar{
Foo!int foo;
}

void main(){
}
```

error: Segmentation fault (core dumped)


The problem is that the compiler will try to generate an inout 
copy constructor for Bar that looks roughly like this:


```
this(ref scope inout(Bar) p) inout
{
this.foo = p;
}
```

The idea behind this lowering is to try and call the copy 
constructor for Foo object if possible. One issue here is that 
copy constructors have the same symbol name as constructors 
(__ctor), so `this.foo = p` gets lowered to `foo.__ctor(p)`.
Since both the instance and the parameter are inout, the copy 
constructor of Foo cannot be called, so the templated constructor 
is called. After generating the template instance of the 
constructor, you end up with `this(scope inout(Foo)) inout` ; 
that is basically an rvalue constructor. This is not valid code; 
if you write:


```
struct Foo(T){
//this(Rhs, this This)(scope Rhs rhs){}
this(scope inout(Foo!int) rhs) inout {}

this(ref scope typeof(this) rhs){
}
}
```

You will get an error stating that you cannot define both an 
rvalue constructor and a copy constructor. However, since the 
constructor is templated it is impossible for the compiler to 
issue this error before actually instantiating the constructor. I 
see 2 possible fixes for this: (1) either we rename the copy 
constructor symbol to __cpCtor so that it does not clash with the 
normal constructor overload set or (2) when a templated 
constructor is instantiated, we can check whether it is an rvalue 
constructor and issue an error if a copy constructor exists.


When I implemented the copy constructor I thought that it would 
better to have the copy constructor on a different overload set 
than the normal constructors, however, Walter insisted that they 
have the same name. So, I guess (2) is the way to go.


Cheers,
RazvanN

Re: No rdmd.exe in /bin64 on Windows - is this an issue?

[RazvanN via Digitalmars-d-learn]

On Monday, 12 July 2021 at 23:57:37 UTC, Scotpip wrote:

Hi guys

Just installed the DMD 2.097.0 .exe download for Windows on my 
64 bit Win 10 workstation.


[...]


PR: https://github.com/dlang/installer/pull/484

Re: Cannot call find with haystack elements having a explicit copy constructors

[RazvanN via Digitalmars-d-learn]

On Thursday, 15 July 2021 at 11:08:25 UTC, Per Nordlöw wrote:

The adding of copy construtors to `Service` defined as

```d
@safe struct Service {
this(ref return scope typeof(this) rhs) {}
this(const ref return scope typeof(this) rhs) const {}
}

@safe struct Session {
void openAndGetService(in string key) scope {
import std.algorithm.searching : find;
auto hit = _pairs.find!((x) => x.key == key)();
}
private Pair[] _pairs;
private struct Pair {
string key;
Service service;
}
}
```



struct Pair will have an inout(inout) copy constructor defined 
the following way:


this(inout ref return scope typeof(this) rhs) inout
{
key = rhs.key;
service = rhs.service;
}

`service = rhs.service` will be rewritten to 
service.__cpctor(rhs.service), but since Service does not define 
an inout copy constructor it will fail to typecheck and the 
compiler will annotate it with @disable. Therefore, Pair will 
become uncopyable. This will result in isInputRange failing on 
Pair[] (more specifically, this constraints from isInputRange: 
is(typeof((return ref R r) => r.front)). If the copy constructor 
of Service is inout(inout), the generated copy constructor of 
Pair will be succesfully typechecked and everything will work.


For more context, please see this issue [1] and more 
specifically, this comment [2].


Cheers,
RazvanN

[1] https://issues.dlang.org/show_bug.cgi?id=20876
[2] https://issues.dlang.org/show_bug.cgi?id=20876#c4

Re: Bug?

[RazvanN via Digitalmars-d-learn]

On Tuesday, 5 May 2020 at 05:37:08 UTC, Simen Kjærås wrote:

On Tuesday, 5 May 2020 at 04:02:06 UTC, RazvanN wrote:

[...]


Surely the above code, which silently discards the exception, 
does not print "hello"?


Regardless, I ran your code with writeln inside the catch(), 
and without the try-catch entirely, with and without nothrow on 
K's destructor. I am unable to replicate the issue on my 
computer with DMD 2.091.0, as well as on run.dlang.io. Is 
something missing in your code here?


--
  Simen


Ah sorry! I was on a branch were I had some other modifications. 
Indeed in git master the issue does not manifest.

Bug?

[RazvanN via Digitalmars-d-learn]

truct K
{
~this() nothrow {}
}

void main()
{
static class C
{
this(K, int) {}
}

static int foo(bool flag)
{
if (flag)
throw new Exception("hello");
return 1;
}

try
{
new C(K(), foo(true));
}
catch(Exception)
{
}
}

Result:

object.Exception@test.d(18): hello

If the destructor of K is not marked nothrow the code does not 
throw an exception. Is this a bug or am I missing something?

Re: std.container.rbtree as Interval Tree?

[RazvanN via Digitalmars-d-learn]

On Monday, 4 February 2019 at 22:54:01 UTC, James Blachly wrote:
I tried to implement an interval tree backed by 
std.container.rbtree today and fell flat.


[...]

You can use alias this [1] in your interval element type:

struct IntervalElem
{
size_t start, end;
/* ... other declarations */
alias start this;
}

[1] https://dlang.org/spec/class.html#AliasThis


Q2: Would replacing "Elem" with a generic type "T" in the 
function signatures for upperBound, lowerBound, and various 
related fns like _firstGreater / _firstGreaterEqual solve this 
problem?


[...]
Elem is already a generic type. I don't know how you can make it 
more generic without adding other template parameters to the 
class declaration (which means reimplementing RBTree from 
std.container);



James

[1] https://dlang.org/spec/operatoroverloading.html#eqcmp ("For 
example ... x and y are disjoint sets, then neither x < y nor y 
< x holds, but that does not imply that x == y. Thus, it is 
insufficient to determine equality purely based on opCmp alone. 
")

Re: Segfault when adding a static destructor in druntime/src/rt/sections_elf_shared.d

[RazvanN via Digitalmars-d-learn]

On Thursday, 10 January 2019 at 23:04:37 UTC, Steven 
Schveighoffer wrote:

On 1/10/19 5:12 PM, RazvanN wrote:
On Thursday, 10 January 2019 at 15:04:25 UTC, Steven 
Schveighoffer wrote:

On 1/8/19 7:54 AM, RazvanN wrote:

[...]


That is a thread-local static destructor. Are any shared 
static destructors accessing the array?


No, there aren't. Indeed, the problem is as Johan as said: the 
loadedDSOs should not be wrapped in an array with a destructor 
because it is manually destroyed.


Hm... is this a sign of how things will be once the (necessary 
IMO) change to destroying globals is deployed?


-Steve


At least for this specific situation, yes.

Re: Segfault when adding a static destructor in druntime/src/rt/sections_elf_shared.d

[RazvanN via Digitalmars-d-learn]

On Thursday, 10 January 2019 at 15:04:25 UTC, Steven 
Schveighoffer wrote:

On 1/8/19 7:54 AM, RazvanN wrote:

[...]


That is a thread-local static destructor. Are any shared static 
destructors accessing the array?


No, there aren't. Indeed, the problem is as Johan as said: the 
loadedDSOs should not be wrapped in an array with a destructor 
because it is manually destroyed.
You might be able to determine this by printf debugging between 
calling unshared and shared destructors.


-Steve

Re: Segfault when adding a static destructor in druntime/src/rt/sections_elf_shared.d

[RazvanN via Digitalmars-d-learn]

On Tuesday, 8 January 2019 at 14:30:24 UTC, Johan Engelen wrote:

On Tuesday, 8 January 2019 at 12:54:11 UTC, RazvanN wrote:

[...]


Great!
(I am _extremely_ surprised that dtors are not called for 
globals.)


[...]


Thanks! This is really helpful!

RazvanN

Segfault when adding a static destructor in druntime/src/rt/sections_elf_shared.d

[RazvanN via Digitalmars-d-learn]

Hi all,

I am working on issue 14650 [1] and I would like to implement a 
solution where static destructors are destroying global 
variables. However, I have the following problem in 
druntime/src/rt/sections_elf_shared:


struct ThreadDSO
{
DSO* _pdso;
static if (_pdso.sizeof == 8) uint _refCnt, _addCnt;
else static if (_pdso.sizeof == 4) ushort _refCnt, _addCnt;
else static assert(0, "unimplemented");
void[] _tlsRange;
alias _pdso this;
// update the _tlsRange for the executing thread
void updateTLSRange() nothrow @nogc
{
_tlsRange = _pdso.tlsRange();
}
}
Array!(ThreadDSO) _loadedDSOs;


For this code, I would have to create the following static 
destructor:


static ~this() { _loadedDSOs.__dtor(); }

Because Array defines a destructor which sets its length to 0.

However this code leads to segfault when compiling any program 
with the runtime (betterC code compiles successfully). In my 
attempt to debug it, I dropped my patch and added the above 
mentioned static destructor manually in druntime which lead to 
the same effect. Interestingly, _loadedDSOs.__dtor runs 
successfully, the segmentation fault comes from somewhere higher 
in the call path (outside of the _d_run_main function (in 
rt/dmain2.d)). I'm thinking that the static destructor somehow 
screws up the object which is later referenced after the main 
program finished executing. Does someone well versed in druntime 
has any ideas what's happening?


Cheers,
RazvanN



[1] https://issues.dlang.org/show_bug.cgi?id=14650

Re: Disabling struct destructor illegal?

[RazvanN via Digitalmars-d-learn]

On Thursday, 19 July 2018 at 09:50:32 UTC, Jim Balter wrote:

On Thursday, 19 July 2018 at 08:50:15 UTC, RazvanN wrote:

struct A
{
int a;
@disable ~this() {}
}

void main()
{
A a = A(2);
}

Currently, this code yields:

Error: destructor `A.~this` cannot be used because it is 
annotated with @disable


I was expecting that disabling the destructor would make it as 
if the struct does not have a destructor


Why? That's not the semantics of @disable. And why would you 
want that? What are you actually trying to achieve?


I just don't understand why you would ever mark the destructor of 
a struct with @disable. When is that useful? If it's not, why not 
just forbit it?

Disabling struct destructor illegal?

[RazvanN via Digitalmars-d-learn]

struct A
{
int a;
@disable ~this() {}
}

void main()
{
A a = A(2);
}

Currently, this code yields:

Error: destructor `A.~this` cannot be used because it is 
annotated with @disable


I was expecting that disabling the destructor would make it as if 
the struct does not have a destructor, instead it makes the 
program not compile. I find this behavior odd: why not make it 
illegal to disable the destructor if disabling it will surely 
result in errors wherever the struct is used. The only situation 
where the code will compile is A is never used directly. To make 
matters even more confusing, this code compiles:


class A
{
int a;
@disable ~this() {}
}

void main()
{
A a = new A();
}


So, is this a bug or am I missing something?

Yoroshiku onegaishimasu,
RazvanN

Re: Class qualifier vs struct qualifier

[RazvanN via Digitalmars-d-learn]

Honestly, from what I understand of how this works, what I find 
weird is the struct case. immutable on classes does _not_ make 
the class itself immutable. It just makes all of its members 
immutable - hence the error about trying to allocate new Foo 
instead of new immutable Foo. So, that is exactly what I would 
expect. And honestly, being able to write Foo and have it imply 
immutable Foo would get _really_ confusing when reading and 
debugging code.


Maybe it has something to do with structs being value types and 
classes
being reference types. If you declare an immutable struct then 
you cannot
modify it's value, while if you declare a class, the pointer to 
the class
is mutable, while the class fields are not. This kind of makes 
sense, however
the thing is that in both situations you are not able to mutate 
any of the
class/struct fields no matter how you instantiate it, so it is 
really redundant

to use `immutable` when creating the instance.

What's bizarre is that marking the struct with immutable would 
affect anything other than its members.


Bar b;

should not claim that typeof(b) is immutable(Bar). b was not 
marked as
immutable. It was listed as Bar, not immutable Bar. So, b 
shouldn't be

immutable.

- Jonathan M Davis

Class qualifier vs struct qualifier

[RazvanN via Digitalmars-d-learn]

Hello,

I'm having a hard time understanding whether this inconsistency 
is a bug or intended behavior:


immutable class Foo {}
immutable struct Bar {}

void main()
{
import std.stdio : writeln;
Foo a;
Bar b;

writeln("typeof(a): ", typeof(a).stringof);
writeln("typeof(b): ", typeof(b).stringof);
}

prints:

typeof(Foo): Foo
typeof(Bar): immutable(Bar)


It seems like the class storage class is not taken into account 
which leads to some awkward situations like:


immutable class Foo
{
this() {}
}

void main()
{
Foo a = new Foo(); // error: immutable method `this` is not 
callable using a

   // mutable object
}

To make it work I have to add immutable to both sides of the 
expression : immutable Foo a = new immutable Foo(); this is a 
wonder of redundancy. I already declared the class as immutable 
so it shouldn't be possible to have mutable instances of it (and 
it isn't), however I am forced to write the immutable twice even 
though it is pretty obvious that the class cannot be mutated.

Constructor qualifiers; bug or expected behavior?

[RazvanN via Digitalmars-d-learn]

Hi all,

Let's say we have this code:

struct B
{
int a;
this(int a) immutable
{
this.a = 7;
}

this(int a)
{
this.a = 10;
}
}

void main()
{
B a = immutable B(2);
writeln(a.a);
a.a = 4;

immutable B a2 = immutable B(3);
writeln(a2.a);
a2.a = 3;// error : cannot modify
}

Both a and a2 will be constructed using the immutable 
constructor, however a is not immutable (a.a = 4 will compile 
fine). Is this the intended behavior? Shouldn't the compiler warn 
me that I'm trying to create a mutable object using the 
constructor for an immutable object? I couldn't find any 
documentation about this.

Re: Understanding the AST...

[RazvanN via Digitalmars-d-learn]

On Thursday, 22 February 2018 at 13:21:04 UTC, joe wrote:

On Monday, 12 February 2018 at 08:47:58 UTC, RazvanN wrote:

Hi Joe,

/SNIP

On Tuesday, 6 February 2018 at 12:03:06 UTC, joe wrote:

[...]


The FuncDeclaration node contains all the information for that.
For example, you can access fd.parent to see if the function is
declared at top-level (in which case, the parent is going to 
be a module
declaration ) or if it is a nested function (in a class, in a 
struct, in a function).
Every AST node contains information about the position in the 
AST, all you
have to do is find how to get that information: which field to 
access or which

member function to call.

/SNIP

Cheers,
RazvanN


Follow up question...

Why is *.parent always null?
e.g.:

extern(C++) class MyVisitor(AST): ParseTimeTransitiveVisitor!AST
{
  override void visit(AST.Import i)
  {
assert(i.parent is null); // always true
  }

  override void visitFuncBody(AST.FuncDeclaration f)
  {
assert(f.parent is null); // always true
  }
}


Indeed, @Stefan is right. The ParseTimeVisitor only contains 
information available at parse time. If you are interested in the 
parent you have 2 options: either (1) use the ParseTimeVisitor 
and implement the AST traversal logic yourself or (2) you can use 
the SemanticTimeTransitiveVisitor in which case the parent is not 
going to be null. In the case of (2) you need to also do some 
semantic analysis (so you need the whole dmd library, not just 
the parsing one). Here's an example on using the dmd library 
(including semantic) [1]. You can copy paste that example and add 
a few lines of code where you instantiate your visitor (which 
will inherit SemanticTimeTransitiveVisitor).


[1] 
https://github.com/dlang/dmd/blob/master/test/dub_package/frontend.d


RazvanN

Re: How to check if aggregate member is static templated method?

[RazvanN via Digitalmars-d-learn]

On Thursday, 15 February 2018 at 13:51:41 UTC, drug wrote:

15.02.2018 16:50, drug пишет:

https://run.dlang.io/is/zHT2XZ
I can check againts if member is either static function or 
template. But I failed to check if it both static and templated.


The best I could come up with is:

struct Foo
{
static staticMethod()
{
}

static templatedStaticMethod(T)(T t)
{
}
}

void main()
{
static if(__traits(isTemplate, Foo.templatedStaticMethod) &&
  __traits(isStaticFunction, 
Foo.templatedStaticMethod!int))

{
 writeln("win");
}
}

It seems like a templated method can be queried if it is static 
only after it's instantiation. Hope this helps.


Cheers,
RazvanN

Re: Understanding the AST...

[RazvanN via Digitalmars-d-learn]

Hi Joe,

I suggest you watch this video which explains how the parse time 
visitors work: https://www.youtube.com/watch?v=tK072jcoWv4 .


On Tuesday, 6 February 2018 at 12:03:06 UTC, joe wrote:

Hello everybody!

Last week end I found this post ( 
https://dlang.org/blog/2017/08/01/a-dub-case-study-compiling-dmd-as-a-library/ ) on the Blog and thought to myself awesome.


So I built the library and everything went smooth. Thanks for 
the effort of all the involved people who made that possible!


I've had a look at the 2 examples, too, the avg. function lines 
( https://github.com/dlang/dmd/blob/master/src/examples/avg.d ) 
and the import ( 
https://github.com/dlang/dmd/blob/master/src/examples/impvisitor.d ) ones and for a start I decided to make a program that prints the outline of a module.


Turns out I don't really understand how to access the data in 
the AST.
For everything there's a visitor method and overriding a few of 
them to print return statements and some such works as 
advertised.


However, I have no idea where I am in the tree when any of 
those methods are called.
Like for example in 
FunctionLengthVisitor(AST).visitFuncBody(AST.FuncDeclaration 
fd).
I have a function declaration object which tells me everything 
about what's inside the function, but how do I know what or 
where this function belongs to, where can I get that 
information ? I don't see anything about UDAs either, nor the 
doc comment.




The FuncDeclaration node contains all the information for that.
For example, you can access fd.parent to see if the function is
declared at top-level (in which case, the parent is going to be a 
module
declaration ) or if it is a nested function (in a class, in a 
struct, in a function).
Every AST node contains information about the position in the 
AST, all you
have to do is find how to get that information: which field to 
access or which

member function to call.

I understand when visitor.getAvgLen is called with the parsed 
module, the accept function calls a visitor overload for each 
member.
But this sounds to me like I'd have to do a lot of book keeping 
in my visitor to keep track of things which are already present 
in the AST.


The function average length visitor inherits a transitive visitor
which means that the AST traversal logic is already implemented 
for you.
All you have to do is override the visiting methods of interest 
and do
whatever suits you : print stuff, alter the ast, stop the 
visitation or

continue the visitation (by calling super.visit(ASTnode)).



Any insight to this would be much appreciated :)


I know that my explanations might not be very explicit, but if 
you have an example please post it and we can work on it.


Cheers,
RazvanN

Re: ddox empty public methods/interfaces etc

[RazvanN via Digitalmars-d-learn]

On Thursday, 9 November 2017 at 14:21:52 UTC, Steven 
Schveighoffer wrote:

On 11/8/17 10:45 PM, Andrey wrote:


I just added to dub.json this:


"-ddoxFilterArgs": [
    "--min-protection=Public"
]


i.e. without --only-documented option, in this way ddox will 
generate documentation for all public methods, even if there 
is no docstring.


Interesting. I misunderstood then how ddox works. I thought the 
json it gets is the output from the ddoc generator, but now I 
realize it's the output from the parser itself.


So sure, this makes sense. Sorry for the misinformation!

-Steve


I don't want to open a new forum thread for this, but if you guys 
have more experience with ddox can you please explain me how does 
it work? I expected you can simply run ddox on a .d file and it 
will output the documentation in some sort of form (json, html or 
whatever), but from what I saw, you need to pass it the json if 
you want to use serve-html/generate-html/filter and you have to 
use dmd to generate the json. Looking on the source code only 
passing serve-test actually parses the .d file, but the 
serve-test doesn't seem to be a public parameter.


Thanks in advance,
RazvanN

Re: std.concurrency.setMaxMailboxSize

[RazvanN via Digitalmars-d-learn]

On Wednesday, 11 October 2017 at 11:26:11 UTC, rikki cattermole 
wrote:

On 11/10/2017 12:09 PM, RazvanN wrote:

Hi all,

I have seen that the concurrency api has this method specified 
in $title [1] and I was wondering what is the use of it? 
Enabling threads to modify the message box of other threads 
doesn't seem to be a good idea and I can't think of any real 
use case.


Best regards,
RazvanN

[1] 
https://dlang.org/phobos/std_concurrency.html#.setMaxMailboxSize


Main controlling thread setting child threads?

Otherwise I don't remember the last time it was mentioned, so 
I'd say leave it be :)


Shouldn't the thread be in charge of its mailbox size? Otherwise, 
main can pass the max size in the constructor.

std.concurrency.setMaxMailboxSize

[RazvanN via Digitalmars-d-learn]

Hi all,

I have seen that the concurrency api has this method specified in 
$title [1] and I was wondering what is the use of it? Enabling 
threads to modify the message box of other threads doesn't seem 
to be a good idea and I can't think of any real use case.


Best regards,
RazvanN

[1] 
https://dlang.org/phobos/std_concurrency.html#.setMaxMailboxSize

Re: D bindings for TensorFlow

[RazvanN via Digitalmars-d-learn]

On Friday, 6 January 2017 at 13:22:28 UTC, llaine wrote:
Did anyone used Tensorflow with D ? I would be really 
interesting to know if some libs allows it right now.


I read an old thread about TS on the forum, but since then 
nothing ...


At the moment there is no support in D to use TensorFlow directly 
(the only way is to create the bindings yourself). There has been 
a discussion, a month ago, about creating a D library which would 
be binded to the C++ implementation, but at the moment no 
conclusion was reached.


Hope this answers your question.

RazvanN

Re: Swap front for char[] input ranges

[RazvanN via Digitalmars-d-learn]

On Monday, 19 December 2016 at 20:26:26 UTC, Ali Çehreli wrote:

On 12/19/2016 06:09 AM, RazvanN wrote:
> [...]
wrote:
>> [...]
InputRanges.
>> [...]
following
> [...]
char[]
> [...]
function, so
> [...]
http://dlang.org/phobos/std_algorithm_mutation.html#bringToFront

[...]


No need to mention it. It is an honor to be able contribute
to this great language.


[...]


That is right, I am working on that particular bug. After talking 
with AndreiA,
I submitted this PR [1]. It treats the case of char[], but I am 
not really sure how the constraints should be applied to the 
function since it seems there are

a lot of combinations (especially if char[] is supported).

[1] https://github.com/dlang/phobos/pull/4970

Re: Swap front for char[] input ranges

[RazvanN via Digitalmars-d-learn]

On Monday, 19 December 2016 at 12:25:02 UTC, Ali Çehreli wrote:

On 12/19/2016 02:41 AM, RazvanN wrote:
> [...]

As your comments make it clear below, they cannot be 
InputRanges.


> [...]
swapping code
>  [...]

Obivously, tmp1 and tmp2 are unusued there. :)

> [...]
passed.
> [...]
state
> [...]
is:
> [...]
input ranges
> [...]

Not possible... It's ok to use something similar to the 
following template constraint:


void foo(R1, R2)(R1 r1, R2 r2)
if ((hasSwappableElements!R1 && hasSwappableElements!R2) ||
(hasLvalueElements!R1 && hasLvalueElements!R2)) {
// ...
}

Ali


In this case, the bringToFront function [1] should not accept 
char[]
as parameters? Or a special path should be added in the function, 
so that char[] are treated specially?


[1] 
http://dlang.org/phobos/std_algorithm_mutation.html#bringToFront

Swap front for char[] input ranges

[RazvanN via Digitalmars-d-learn]

Hi,

I have a function which accepts 2 input Ranges and swaps the 
first element in Range1 with the first element in Range2. The 
swapping code looks something like this :


 static if (is(typeof(swap(r1.front, r2.front
 {
 swap(r1.front, r2.front);
 }
 else
 {
 auto t1 = moveFront(r1), t2 = moveFront(r2);
 auto tmp1 = r1.front;
 auto tmp2 = r2.front;
 r1.front = move(t2);
 r2.front = move(t1);
 }

This code works for most cases, except when 2 char[] are passed.
In that case, the compilation fails with error messages which 
state

that r1.front and r2.front are not Lvalues. So, my question is:
how can I swap the 2 elements since in the case of char[] input 
ranges

the front property does not return a reference?

Range of uncopyable elements

[RazvanN via Digitalmars-d-learn]

Hi,

I am trying to create a range with uncopyable elements. My 
thought process was the following:


1.I have created a struct :

struct S
{
int a;

@disable this(this);
}

2. I declared an array :

S[] arr = [S(1), S(2), S(3)];

expecting that arr will be a range like, for example, an int[].
I was surprised to see that isInputRange!arr is false.

So, is there any possibility to create a range with uncopyable 
elements?

Re: Char representation

[RazvanN via Digitalmars-d-learn]

On Tuesday, 22 November 2016 at 14:23:28 UTC, Jonathan M Davis 
wrote:
On Tuesday, November 22, 2016 13:29:47 RazvanN via 
Digitalmars-d-learn wrote:

[...]


You misunderstand. char[] is a dynamic array of char, wchar[] 
is a dynamic array of wchar[], and dchar[] is a dynamic array 
of dchar. There is nothing funny going on with the internal 
representation. Rather, the problem is with the range API and 
the traits that go with it. And it's not a bug; it's a design 
mistake.


[...]


Thank you very much for this great explanation. Things are 
starting to make sense now.


Razvan Nitu

Char representation

[RazvanN via Digitalmars-d-learn]

Given the following code:

 char[5] a = ['a', 'b', 'c', 'd', 'e'];
 alias Range = char[];
 writeln(is(ElementType!Range == char));

One would expect that the program will print true. In fact, it 
prints false and I noticed that if Range is char[], wchar[], 
dchar[], string, wstring, dstring
Unqual!(ElementType!Range) is dchar. I find it odd that the 
internal representation for char and string is dchar. Is this a 
bug?

Re: The return of std.algorithm.find

[RazvanN via Digitalmars-d-learn]

On Tuesday, 15 November 2016 at 09:43:27 UTC, RazvanN wrote:
The find function which receives an input haystack and a needle 
returns the haystack advanced to the first occurrence of the 
needle. For normal ranges this is fine, but for

sorted ranges (aka SortedRange) it is a bit odd. For example:

find(assumeSorted[1, 2, 4, 5, 6, 7], 4) would return [4, 5, 6, 
7]. This is in terms with the general policy of the find 
function, but is weird. Since we know the range is sorted, 
shouldn't the result be [1, 2, 4]?


The whole function is find!"a <= b"(assumeSorted([1, 2, 4, 5, 6, 
7]), 4). And the result is

the whole range [1, 2, 4, 5, 6, 7].

The return of std.algorithm.find

[RazvanN via Digitalmars-d-learn]

The find function which receives an input haystack and a needle 
returns the haystack advanced to the first occurrence of the 
needle. For normal ranges this is fine, but for

sorted ranges (aka SortedRange) it is a bit odd. For example:

find(assumeSorted[1, 2, 4, 5, 6, 7], 4) would return [4, 5, 6, 
7]. This is in terms with the general policy of the find 
function, but is weird. Since we know the range is sorted, 
shouldn't the result be [1, 2, 4]?

Re: Concatenate 2 ranges

[RazvanN via Digitalmars-d-learn]

On Friday, 11 November 2016 at 13:33:20 UTC, Vladimir Panteleev 
wrote:

On Friday, 11 November 2016 at 13:30:17 UTC, RazvanN wrote:
I know that I can use the .array property, but I think that 
this iterates through all of my elements. Using 
assumeSorted(chain(r1, r2).array) will return a SortedRange, 
but I am not sure what the complexity for this operation is.


.array allocates, so it's going to be O(n), but the allocation 
will probably be more expensive.


Is there a way to concatenate 2 ranges (SortedRange in my 
case) in O(1) time?


assumeSorted(chain(a, b)) ?

This works for me:

auto r = assumeSorted(chain([1, 2, 3].sort(), [1, 2, 
3].sort()));


It does work, the problem is that [1, 2, 3].sort() is of type 
SortedRange(int[], "a < b") while r is of type 
SortedRange(Result, "a < b"). This is a problem if you want to 
return r in a function which has return type SortedRange(int[], 
"a < b").

Concatenate 2 ranges

[RazvanN via Digitalmars-d-learn]

I am trying to concatenate 2 ranges of the same type (SortedRange 
in my case). I have tried merge, join and chain, but the problem 
is that the result is not an object of the type of the initial 
ranges. For example:


1. If I use chain(r1, r2), the result will be an object of type 
Result which I cannot cast to my specific type (SortedRange).


2. If I use merge(r1, r2), the result will be an object of type 
Merge!(typeof(r1), typeof(r)).


I know that I can use the .array property, but I think that this 
iterates through all of my elements. Using assumeSorted(chain(r1, 
r2).array) will return a SortedRange, but I am not sure what the 
complexity for this operation is.


Is there a way to concatenate 2 ranges (SortedRange in my case) 
in O(1) time?

Re: is operator and SortedRange

[RazvanN via Digitalmars-d-learn]

On Friday, 11 November 2016 at 12:02:10 UTC, ketmar wrote:

On Friday, 11 November 2016 at 11:49:25 UTC, RazvanN wrote:

[...]



template isSortedRange(T) {
  private import std.range : SortedRange;
  static if (is(T : SortedRange!TT, TT)) {
enum isSortedRange = true;
  } else {
enum isSortedRange = false;
  }
}


void main () {
  import std.algorithm : sort;
  int[] a;
  a ~= [1, 6, 3];
  auto b = a.sort;
  pragma(msg, typeof(b));
  pragma(msg, isSortedRange!(typeof(a))); // false
  pragma(msg, isSortedRange!(typeof(b))); // true
}


Thank you! Worked like a charm

is operator and SortedRange

[RazvanN via Digitalmars-d-learn]

I am a bit confused about how the is operator works. I have a 
function which receives an InputRange and a predicate. Now I need 
to be able to test if the InputRange is actually a SortedRange. I 
don't care about how the datatypes behind the SortedRange or the 
predicate, I just need to see if the object is a SortedRange. I 
have tried the following test:


static if(is(typeof(haystack) == SortedRange!(T, _pred), T, 
_pred))


where haystack is the InputRange, but the test fails. Is there a 
way to test if the InputRange is a SortedRange without having to 
explicitly pass the primitive tupe on top of which the 
SortedRange is built?

Obtain predicate from SortedRange

[RazvanN via Digitalmars-d-learn]

Given a SortedRange object, is there a way to obtain the 
predicate which was used for it to be sorted?

Re: typeof(SortedRange) and is operator

[RazvanN via Digitalmars-d-learn]

On Tuesday, 8 November 2016 at 13:59:19 UTC, Nicholas Wilson 
wrote:

On Tuesday, 8 November 2016 at 13:22:35 UTC, RazvanN wrote:
Sorry, I accidentally posted the above message and I don't 
know how to erase it.


You can't, this is a mailing list not a forum.


The following post is the complete one:

Given the following code:

int[] arr = [1, 2, 9, 4, 10, 6];
auto r= sort(arr);

if(is(typeof(r) == SortedRange!(int[], "a expression` lambdas don't work 
at all in template expressions.


`SortedRange!(int[], "a

Re: typeof(SortedRange) and is operator

[RazvanN via Digitalmars-d-learn]

Sorry, I accidentally posted the above message and I don't know 
how to erase it.

The following post is the complete one:

Given the following code:

int[] arr = [1, 2, 9, 4, 10, 6];
auto r= sort(arr);

if(is(typeof(r) == SortedRange!(int[], "a

typeof(SortedRange) and is operator

[RazvanN via Digitalmars-d-learn]

Given the following code:

int[] arr = [1, 2, 9, 4, 10, 6];
auto r= sort(arr);

if(is(typeof(r) == SortedRange!(int[], "a