Re: parameter pack to inputRange

[Ali Çehreli via Digitalmars-d-learn]

On 05/05/2016 10:00 PM, Erik Smith wrote:

Is there an existing way to adapt a parameter pack to an input range? I
would like to construct an array with it.  Example:

void run(A...) (A args) {
  Array!int a(toInputRange(args));
}



Inspired by my DConf 2016 talk ;) here is a fiber-based InputRange solution:

import std.stdio;
import std.concurrency;
import std.container;

alias GeneratorFiber = std.concurrency.Generator;

void run(A...) (A args) {
void asInputRange() {
/* static */ foreach (arg; args) {
yield(arg);
}
}

auto range =  new GeneratorFiber!int();
auto a = Array!int(range);
writeln(a[]);
}

void main() {
run(1, 2, 3);
}

Ali

Re: parameter pack to inputRange

[Ali Çehreli via Digitalmars-d-learn]

On 05/05/2016 10:00 PM, Erik Smith wrote:

Is there an existing way to adapt a parameter pack to an input range? I
would like to construct an array with it.  Example:

void run(A...) (A args) {
  Array!int a(toInputRange(args));
}



Just initialize an array with the arguments:

void run(A...) (A args) {
writeln([args]);
}

Ali

parameter pack to inputRange

[Erik Smith via Digitalmars-d-learn]

Is there an existing way to adapt a parameter pack to an input 
range? I would like to construct an array with it.  Example:


void run(A...) (A args) {
 Array!int a(toInputRange(args));
}

Re: How the heck is onInvalidMemoryOperationError() nothrow?

[tsbockman via Digitalmars-d-learn]

On Friday, 6 May 2016 at 02:57:59 UTC, Jeremy DeHaan wrote:
In core.exception, we have a lovely function called 
onInvalidMemoryOperationError(). This function is marked as 
nothrow (plus other annotations). This function literally does 
nothing except throwing an error. How can it be marked as 
nothrow?


From the spec 
(https://dlang.org/spec/function.html#nothrow-functions):
"Nothrow functions can only throw exceptions derived from 
class Error."


Throwing an Error is, for many purposes, considered fundamentally 
different than throwing an Exception because Error objects aren't 
meant to be caught by user code. Throwing an Error is supposed to 
just be a way of crashing the program with a nice message and 
stack trace.


A key benefit of this distinction, is that it enables the use of 
`assert()` statements in `nothrow` code.

How the heck is onInvalidMemoryOperationError() nothrow?

[Jeremy DeHaan via Digitalmars-d-learn]

In core.exception, we have a lovely function called 
onInvalidMemoryOperationError(). This function is marked as 
nothrow (plus other annotations). This function literally does 
nothing except throwing an error. How can it be marked as nothrow?

Re: what's the right way to get char* from string?

[Alex Parrill via Digitalmars-d-learn]

On Thursday, 5 May 2016 at 07:49:46 UTC, aki wrote:

extern (C) int strcmp(char* string1, char* string2);


This signature of strcmp is incorrect. strcmp accepts const char* 
arguments [1], which in D would be written as const(char)*. The 
immutable(char)* values returned from toStringz are implicitly 
convertible to const(char)* and are therefore useable as-is as 
arguments to strcmp.


import std.string;
extern (C) int strcmp(const(char)* string1, const(char)* string2);
auto v = strcmp(somestring1.toStringz, somestring2.toStringz);

[1] http://linux.die.net/man/3/strcmp

Re: template auto instantiation when parameters empty

[Steven Schveighoffer via Digitalmars-d-learn]

On 5/5/16 6:50 PM, Erik Smith wrote:


Alias works at the cost of adding a 2nd type name:

alias Res = Resource!();
auto res  = Res.create

The other problem is that the alias definition by itself instantiates,
which I can't afford.

I have createResource() now, it just doesn't fit well with the rest of
the calling styles.

There is also this approach, which might be slightly more idiomatic

struct Resource(T) {}
struct Policy {}

auto create(alias T)() {
 T!Policy r;
 return r;
}

auto r = create!Resource;


I believe factory external IFTI functions are quite idiomatic. They are 
all over phobos.


-Steve

Re: template auto instantiation when parameters empty

[Erik Smith via Digitalmars-d-learn]

On Thursday, 5 May 2016 at 16:12:40 UTC, Steven Schveighoffer 
wrote:

On 5/5/16 12:10 AM, Erik Smith wrote:
I want to have a struct template auto instantiate when the 
template

parameters are defaulted or missing.  Example:

struct Resource(T=int) {
 static auto create() {return Resource(null);}
 this(string s) {}
}

auto resource = Resource.create;

As a plain struct it works, but not as a template:

struct Resource {   // works
struct Resource() {  // fails
struct Resource(T=int) {  // fails

At the call site, this works, but I'm hoping for a few less 
symbols:


auto resource = Resource!().create;

Any ideas?


Instead of static method, use an external factory method:

static auto createResource(T = int)()
{
   return Resource!T(null);
}

And I wouldn't bother with making Resource's T have a default, 
as you'd still have to instantiate it with Resource!() to get 
the default.


-Steve


Alias works at the cost of adding a 2nd type name:

alias Res = Resource!();
auto res  = Res.create

The other problem is that the alias definition by itself 
instantiates, which I can't afford.


I have createResource() now, it just doesn't fit well with the 
rest of the calling styles.


There is also this approach, which might be slightly more 
idiomatic


struct Resource(T) {}
struct Policy {}

auto create(alias T)() {
T!Policy r;
return r;
}

auto r = create!Resource;

Re: template auto instantiation when parameters empty

[Steven Schveighoffer via Digitalmars-d-learn]

On 5/5/16 12:10 AM, Erik Smith wrote:

I want to have a struct template auto instantiate when the template
parameters are defaulted or missing.  Example:

struct Resource(T=int) {
 static auto create() {return Resource(null);}
 this(string s) {}
}

auto resource = Resource.create;

As a plain struct it works, but not as a template:

struct Resource {   // works
struct Resource() {  // fails
struct Resource(T=int) {  // fails

At the call site, this works, but I'm hoping for a few less symbols:

auto resource = Resource!().create;

Any ideas?


Instead of static method, use an external factory method:

static auto createResource(T = int)()
{
   return Resource!T(null);
}

And I wouldn't bother with making Resource's T have a default, as you'd 
still have to instantiate it with Resource!() to get the default.


-Steve

Re: what's the right way to get char* from string?

[Steven Schveighoffer via Digitalmars-d-learn]

On 5/5/16 3:36 PM, Steven Schveighoffer wrote:

Only thing I can think of is.. um... horrible:

char *toCharz(string s)
{
auto cstr = s.toStringz;
return cstr[0 .. s.length + 1].dup.ptr;
}


Ignore this. What Jonathan said :)

-Steve

Re: what's the right way to get char* from string?

[aki via Digitalmars-d-learn]

On Thursday, 5 May 2016 at 11:35:09 UTC, Jonathan M Davis wrote:
If you want a different mutability, then use the more general 
function std.utf.toUTFz. e.g. from the documentation:


auto p1 = toUTFz!(char*)("hello world");
auto p2 = toUTFz!(const(char)*)("hello world");
auto p3 = toUTFz!(immutable(char)*)("hello world");
auto p4 = toUTFz!(char*)("hello world"d);
auto p5 = toUTFz!(const(wchar)*)("hello world");
auto p6 = toUTFz!(immutable(dchar)*)("hello world"w);

- Jonathan M Davis


Ah! This can be a solution.
Thanks Jonathan.

-- aki.

Re: Show window maximized in DlangUI

[default0 via Digitalmars-d-learn]

On Thursday, 5 May 2016 at 14:10:14 UTC, Vadim Lopatin wrote:

On Thursday, 5 May 2016 at 07:53:43 UTC, default0 wrote:

Hi

I'm writing a D Desktop application using DlangUI.
I want the window it creates to start maximized (but not 
Fullscreen) and could not find any APIs in the documentation 
that seem to do this.


Does anyone know how to do this?


No such functionality yet.
Could you please submit feature request on github?


https://github.com/buggins/dlangui/issues/258 done :)

Re: Unique Enum Members

[Mark Isaacson via Digitalmars-d-learn]

On Thursday, 5 May 2016 at 12:54:08 UTC, Nordlöw wrote:
Is there a way to calculate unique enum members without using 
sort, such as *not* done in my current implementation:


auto uniqueEnumMembers(T)()
{
import std.traits: EnumMembers;
import std.algorithm: sort, uniq;
return [EnumMembers!T].sort().uniq;
}

Preferrably both at compile-time and run-time.


Sure, if you can hash the underlying type this should do the 
trick in linear time: 
http://melpon.org/wandbox/permlink/Rvq60fv7jOIPuhXz

Re: Show window maximized in DlangUI

[Vadim Lopatin via Digitalmars-d-learn]

On Thursday, 5 May 2016 at 07:53:43 UTC, default0 wrote:

Hi

I'm writing a D Desktop application using DlangUI.
I want the window it creates to start maximized (but not 
Fullscreen) and could not find any APIs in the documentation 
that seem to do this.


Does anyone know how to do this?


No such functionality yet.
Could you please submit feature request on github?

Re: what's the right way to get char* from string?

[Steven Schveighoffer via Digitalmars-d-learn]

On 5/5/16 11:53 AM, pineapple wrote:

On Thursday, 5 May 2016 at 07:49:46 UTC, aki wrote:

Hello,

When I need to call C function, often need to
have char* pointer from string.


This might help:

import std.traits : isSomeString;
import std.string : toStringz;

extern (C) int strcmp(char* string1, char* string2);

int strcmpD0(S)(in S lhs, in S rhs) if(is(S == string) || is(S ==
const(char)[])) { // Best
 return strcmp(
 cast(char*) toStringz(lhs),
 cast(char*) toStringz(rhs)
 );
}


This is likely a correct solution, because strcmp does not modify any 
data in the string itself.


Practically speaking, you can define strcmp as taking const(char)*. This 
is what druntime does: http://dlang.org/phobos/core_stdc_string.html#.strcmp



int strcmpD1(S)(in S lhs, in S rhs) if(is(S == string) || is(S ==
const(char)[])) { // Works
 return strcmp(
 cast(char*) lhs.ptr,
 cast(char*) rhs.ptr
 );
}


Note, this only works if the strings are literals. Do not use this 
mechanism in general.



/+
int strcmpD2(S)(in S lhs, in S rhs) if(is(S == string) || is(S ==
const(char)[])) { // Breaks
 return strcmp(
 toStringz(lhs),
 toStringz(rhs)
 );
}
+/


Given a possibility that you are calling a C function that may actually 
modify the data, there isn't a really good way to do this.


Only thing I can think of is.. um... horrible:

char *toCharz(string s)
{
   auto cstr = s.toStringz;
   return cstr[0 .. s.length + 1].dup.ptr;
}

-Steve

Re: Async or event library

[Dsby via Digitalmars-d-learn]

On Thursday, 5 May 2016 at 08:19:26 UTC, chmike wrote:
Hello I have seen the wiki page 
https://wiki.dlang.org/Event_system and would like to know the 
current status. Is there a working group for this subject ? 
This is a topic I'm interested in and did some modest work on 
some years ago.


[...]


We has one: Collie, now is in develop, and use in our server. Use 
for TCP and http.

It like facebook/wangle: https://github.com/putao-dev/collie

Unique Enum Members

[Nordlöw via Digitalmars-d-learn]

Is there a way to calculate unique enum members without using 
sort, such as *not* done in my current implementation:


auto uniqueEnumMembers(T)()
{
import std.traits: EnumMembers;
import std.algorithm: sort, uniq;
return [EnumMembers!T].sort().uniq;
}

Preferrably both at compile-time and run-time.

Re: what's the right way to get char* from string?

[Jonathan M Davis via Digitalmars-d-learn]

On Thu, 05 May 2016 07:49:46 +
aki via Digitalmars-d-learn  wrote:

> Hello,
>
> When I need to call C function, often need to
> have char* pointer from string.
>
> "Interfacing to C++" page:
> https://dlang.org/spec/cpp_interface.html
> have following example.
>
> extern (C) int strcmp(char* string1, char* string2);
> import std.string;
> int myDfunction(char[] s)
> {
>  return strcmp(std.string.toStringz(s), "foo");
> }
>
> but this is incorrect because toStringz() returns immutable
> pointer.
> One way is to write mutable version of toStringz()
>
> char* toStringzMutable(string s) @trusted pure nothrow {
>  auto copy = new char[s.length + 1];
>  copy[0..s.length] = s[];
>  copy[s.length] = 0;
>  return copy.ptr;
> }
>
> But I think this is common needs,
> why it is not provided by Phobos?
> (or tell me if it has)

If you want a different mutability, then use the more general function
std.utf.toUTFz. e.g. from the documentation:

auto p1 = toUTFz!(char*)("hello world");
auto p2 = toUTFz!(const(char)*)("hello world");
auto p3 = toUTFz!(immutable(char)*)("hello world");
auto p4 = toUTFz!(char*)("hello world"d);
auto p5 = toUTFz!(const(wchar)*)("hello world");
auto p6 = toUTFz!(immutable(dchar)*)("hello world"w);

- Jonathan M Davis

Re: what's the right way to get char* from string?

[pineapple via Digitalmars-d-learn]

On Thursday, 5 May 2016 at 07:49:46 UTC, aki wrote:

Hello,

When I need to call C function, often need to
have char* pointer from string.


This might help:

import std.traits : isSomeString;
import std.string : toStringz;

extern (C) int strcmp(char* string1, char* string2);

int strcmpD0(S)(in S lhs, in S rhs) if(is(S == string) || is(S == 
const(char)[])) { // Best

return strcmp(
cast(char*) toStringz(lhs),
cast(char*) toStringz(rhs)
);
}
int strcmpD1(S)(in S lhs, in S rhs) if(is(S == string) || is(S == 
const(char)[])) { // Works

return strcmp(
cast(char*) lhs.ptr,
cast(char*) rhs.ptr
);
}

/+
int strcmpD2(S)(in S lhs, in S rhs) if(is(S == string) || is(S == 
const(char)[])) { // Breaks

return strcmp(
toStringz(lhs),
toStringz(rhs)
);
}
+/

void main(){
import std.stdio;
writeln(strcmpD0("foo", "bar")); // Best
writeln(strcmpD1("foo", "bar")); // Works
//writeln(strcmpD2("foo", "bar")); // Breaks
}

Re: Strange stack variable corruption error after calling extern(C) function

[Benjamin Thaut via Digitalmars-d-learn]

On Wednesday, 4 May 2016 at 17:53:32 UTC, cc wrote:


The OS is Win64 though the program is being compiled as 32-bit 
and I'm using the 32-bit distributed DLL.
fmod.dll: PE32 executable (DLL) (GUI) Intel 80386, for MS 
Windows


Tried int and long as the return type, same issue both ways.  
Tried void too just in case, same thing though.


Could you please post the definition of FMOD_RESULT. Its possible 
that the create sound function returns it on stack and not inside 
a register. This is usually the case if FMOD_RESULT is defined as 
a struct in C/C++. But its hard to say. In your case I would 
actually look at the disassembly and step through it to see where 
its going wrong and messing up the stack.

Re: Async or event library

[rikki cattermole via Digitalmars-d-learn]

Event loops needs to be thread local not per process.
So many API's such as WinAPI for e.g. GUI's have this requirement in it 
that its just not worth fighting over.

Re: Async or event library

[chmike via Digitalmars-d-learn]

I would like to add that the switchable TLS is only a half backed 
solution. It would't work in a multi core context where threads 
are truly executing in parallel. Two such threads might get the 
same TLS context which would invalidate its implicit predicate.


Another strategy would be to forbit use of TLS with threads using 
the event loop. But this might break existing code.

Async or event library

[chmike via Digitalmars-d-learn]

Hello I have seen the wiki page 
https://wiki.dlang.org/Event_system and would like to know the 
current status. Is there a working group for this subject ? This 
is a topic I'm interested in and did some modest work on some 
years ago.


At the bottom of the wiki page there is an innocent question 
regarding TLS which is quite devastating. A worker thread pool 
system would not support affinity between threads and callback 
context. Unfortunately, D relies on Thread Local Storage for semi 
global data. This would be error prone. I saw such error case 
with people using TLS with Corba.


One way out of this apparent deadlock is if D would provide its 
own TLS that can be switched between threads. This would allow to 
preserve affinity between threads and callback execution context. 
Unfortunately, it would introduce an overhead to access the data 
in the local storage due to the required indirection. It would 
also require that the compiler is adapted.


When fibers and multithreading support is built in the language, 
as in Go, the compiler can do the magic.


I would like to underline that the server side of software 
development is the easiset side to conquer because the client 
side as to many different GUIs and execution contexts. But it 
requieres that the performances are on par with other languages 
like C, C++, Go or Java.

Show window maximized in DlangUI

[default0 via Digitalmars-d-learn]

Hi

I'm writing a D Desktop application using DlangUI.
I want the window it creates to start maximized (but not 
Fullscreen) and could not find any APIs in the documentation that 
seem to do this.


Does anyone know how to do this?

what's the right way to get char* from string?

[aki via Digitalmars-d-learn]

Hello,

When I need to call C function, often need to
have char* pointer from string.

"Interfacing to C++" page:
https://dlang.org/spec/cpp_interface.html
have following example.

extern (C) int strcmp(char* string1, char* string2);
import std.string;
int myDfunction(char[] s)
{
return strcmp(std.string.toStringz(s), "foo");
}

but this is incorrect because toStringz() returns immutable 
pointer.

One way is to write mutable version of toStringz()

char* toStringzMutable(string s) @trusted pure nothrow {
auto copy = new char[s.length + 1];
copy[0..s.length] = s[];
copy[s.length] = 0;
return copy.ptr;
}

But I think this is common needs,
why it is not provided by Phobos?
(or tell me if it has)

Thanks,
aki

Re: template auto instantiation when parameters empty

[Andrea Fontana via Digitalmars-d-learn]

On Wednesday, 4 May 2016 at 22:10:16 UTC, Erik Smith wrote:

Any ideas?


Using an alias could be a solution.