Re: returning D string from C++?

[Marco Leise via Digitalmars-d-learn]

Am Sat, 05 Aug 2017 20:17:23 +
schrieb bitwise :

>  virtual DString getTitle() const {
>  DString ret;
>  ret.length = GetWindowTextLength(_hwnd) + 1;
>  ret.ptr = (const char*)gc_malloc(ret.length, 0xA, NULL);
>  GetWindowText(_hwnd, (char*)ret.ptr, ret.length);
>  return ret;
>  }

In due diligence, you are casting an ANSI string into a UTF-8
string which will result in broken Unicode for non-ASCII window
titles. In any case it is better to use the wide-character
versions of Windows-API functions nowadays. (Those ending in
'W' instead of 'A'). Starting with Windows 2000, the core was
upgraded to UTF-16[1], which means you don't have to
implement the lossy conversion to ANSI code pages and end up
like this ...

[information loss]
   UTF-8 <-> Windows codepage <-> UTF-16
  ||
  in your code inside Windows

... but instead directly pass and get Unicode strings like
this ...

   UTF-8 <-> UTF-16
  |
  in your code

string to zero terminated UTF-16:
http://dlang.org/phobos/std_utf.html#toUTF16z
zero terminated UTF-16 to string:
ptr.to!string() or just ptr[0..len] if known

Second I'd like to mention that you should have set
ret.length = GetWindowText(_hwnd, (char*)ret.ptr, ret.length);
Currently your length is anything from 1 to N bytes longer
than the actual string[2], which is not obvious because any
debug printing or display of the string stops at the embedded
\0 terminator.

[1] https://en.wikipedia.org/wiki/Unicode_in_Microsoft_Windows
[2]
https://msdn.microsoft.com/de-de/library/windows/desktop/ms633521(v=vs.85).aspx

-- 
Marco

Re: Create class on stack

[FoxyBrown via Digitalmars-d-learn]

On Sunday, 6 August 2017 at 02:32:05 UTC, Adam D. Ruppe wrote:

On Sunday, 6 August 2017 at 02:19:19 UTC, FoxyBrown wrote:
Also, does it do the allocation at compile time(reserve space 
on the stack for the variable along with all the others or 
does it "allocate" space on the stack at runtime?... which is 
slightly slower).


compile time. It works like a static array of the appropriate 
size.


though the cost if ti was at runtime is small regardless. I 
think it is just a register subtract.


yeah, I know, but no need for it ;) Still better than the heap 
but was just curious ;) No need to waste cycles if it's not 
necessary.

Re: Create class on stack

[Adam D. Ruppe via Digitalmars-d-learn]

On Sunday, 6 August 2017 at 02:19:19 UTC, FoxyBrown wrote:
Also, does it do the allocation at compile time(reserve space 
on the stack for the variable along with all the others or does 
it "allocate" space on the stack at runtime?... which is 
slightly slower).


compile time. It works like a static array of the appropriate 
size.


though the cost if ti was at runtime is small regardless. I think 
it is just a register subtract.

Re: Create class on stack

[FoxyBrown via Digitalmars-d-learn]

On Sunday, 6 August 2017 at 02:10:31 UTC, Moritz Maxeiner wrote:

On Sunday, 6 August 2017 at 01:18:50 UTC, Johnson Jones wrote:
On Saturday, 5 August 2017 at 23:09:09 UTC, Moritz Maxeiner 
wrote:
On Saturday, 5 August 2017 at 17:08:32 UTC, Johnson Jones 
wrote:
using gtk, it has a type called value. One has to use it to 
get the value of stuff but it is a class. Once it is used, 
one doesn't need it.


Ideally I'd like to treat it as a struct since I'm using it 
in a delegate I would like to minimize unnecessary 
allocations. Is there any way to get D to allocate a class 
on the stack like a local struct?


The easy way is through std.typecons.scoped [1].
Here be dragons, though, because classes are reference types.

[1] https://dlang.org/phobos/std_typecons.html#.scoped


Thanks, I didn't think it created on the stack but it makes 
sense to do so.


See the source [1] as to why: typeof(scoped!T) is a 
(non-copyable) struct that holds the memory for the T object 
inside it.



The only issue is that it escaping the reference?


Yes, don't escape references, that's the reason for my comment:

Here be dragons, though, because classes are reference types.


[1] 
https://github.com/dlang/phobos/blob/v2.075.0/std/typecons.d#L6613


I don't think you understand what I'm saying.

If I use this method to create a "reference" type on the stack 
rather than the heap, is the only issue worrying about not having 
that variable be used outside that scope(i.e., have it "escape")?


Obviously since it's on the stack it will be invalid after the 
function call, but I'm talking about other pitfalls. I don't see 
any but I want to be sure. Also, does it do the allocation at 
compile time(reserve space on the stack for the variable along 
with all the others or does it "allocate" space on the stack at 
runtime?... which is slightly slower).

Re: Create class on stack

[Moritz Maxeiner via Digitalmars-d-learn]

On Sunday, 6 August 2017 at 01:18:50 UTC, Johnson Jones wrote:
On Saturday, 5 August 2017 at 23:09:09 UTC, Moritz Maxeiner 
wrote:
On Saturday, 5 August 2017 at 17:08:32 UTC, Johnson Jones 
wrote:
using gtk, it has a type called value. One has to use it to 
get the value of stuff but it is a class. Once it is used, 
one doesn't need it.


Ideally I'd like to treat it as a struct since I'm using it 
in a delegate I would like to minimize unnecessary 
allocations. Is there any way to get D to allocate a class on 
the stack like a local struct?


The easy way is through std.typecons.scoped [1].
Here be dragons, though, because classes are reference types.

[1] https://dlang.org/phobos/std_typecons.html#.scoped


Thanks, I didn't think it created on the stack but it makes 
sense to do so.


See the source [1] as to why: typeof(scoped!T) is a 
(non-copyable) struct that holds the memory for the T object 
inside it.



The only issue is that it escaping the reference?


Yes, don't escape references, that's the reason for my comment:

Here be dragons, though, because classes are reference types.


[1] 
https://github.com/dlang/phobos/blob/v2.075.0/std/typecons.d#L6613

gtkD: events being triggered twice

[Johnson Jones via Digitalmars-d-learn]

GtkEventBox - Enter
GtkEventBox - Enter
Down
GtkEventBox - Leave
Up
GtkEventBox - Leave
GtkEventBox - Leave

That is when I move the mouse over the event box then click then 
move out out then release.


I would expect

Enter Down Leave Up

The fact that enter and leave are not paired equally is a 
problem. Can be worked around but seems like it would be a bug.


the code is simply


ebox.addOnEnterNotify(delegate(Event e, Widget w)
{   
writeln(w.getName(), " - ", "Enter");
return true;
});

ebox.addOnLeaveNotify((Event e, Widget w)
{   writeln(w.getName(), " 
- ", "Leave");
return true;
});

Re: Create class on stack

[Johnson Jones via Digitalmars-d-learn]

On Saturday, 5 August 2017 at 23:09:09 UTC, Moritz Maxeiner wrote:

On Saturday, 5 August 2017 at 17:08:32 UTC, Johnson Jones wrote:
using gtk, it has a type called value. One has to use it to 
get the value of stuff but it is a class. Once it is used, one 
doesn't need it.


Ideally I'd like to treat it as a struct since I'm using it in 
a delegate I would like to minimize unnecessary allocations. 
Is there any way to get D to allocate a class on the stack 
like a local struct?


The easy way is through std.typecons.scoped [1].
Here be dragons, though, because classes are reference types.

[1] https://dlang.org/phobos/std_typecons.html#.scoped


Thanks, I didn't think it created on the stack but it makes sense 
to do so. The only issue is that it escaping the reference?

Re: Getting enum from value

[Kreikey via Digitalmars-d-learn]

On Saturday, 5 August 2017 at 20:11:27 UTC, Matthew Remmel wrote:

On Saturday, 5 August 2017 at 18:26:10 UTC, Kreikey wrote:

On Saturday, 5 August 2017 at 15:33:57 UTC, Matthew Remmel


I'm annoyed that I didn't think of trying to cast it. That 
works great if the value exists in the enum. It does something 
weird if the value doesn't though. This is my test.d file:


import std.stdio;

enum Foo {
A = "AV",
B = "BV"
}

void main() {
Foo k = cast(Foo)"BV"; // Works and prints correctly

k = cast(Foo)"CV";
writeln("Type: ", typeid(k));  // Type: test.Foo
writeln("Value: ", k);   // Value: cast(Foo)CV
}

The output shows the type being the Foo enum but the value is 
'cast(Foo)CV'. I would of expected an error or exception to be 
thrown if it wasn't able to cast into an actual enum member. Is 
this something with how the enums are implemented under the 
hood?


That was my first post on this forum, so I'm glad it was at least 
a little bit useful :-D
I think the reasoning for no error on bad casts is that casting 
is a blunt instrument that assumes the programmer knows what he's 
doing, and it breaks the type system. So you'd want to use one of 
the aforementioned solutions if you're set on using enums in this 
way. You might also consider using associative arrays, but it's 
also a bit cumbersome. There's no way to get around searching:


  capitals = [
"Indiana" : "Indianapolis",
"Illinois" : "Chicago",
"Ohio" : "Columbus"
  ];
  auto r = capitals.byKeyValue.find!((a, b) => a.value == 
b)("Chicago");

  if (!r.empty) {
writeln(capitals[r.front.key]);
  } else {
writeln("not found");
  }

You could also define another associative array statesByCapital 
with the key : value orders reversed, and then you could also do 
statesByCapitol["Chicago"]. Of course then you'd have to keep 
things in sync if things change. But I discovered a neat trick 
you could use to generate such a two way mapping. You could 
define one array string[] capitals, and another array string[] 
states. Then you could do:


auto capitalsByState = assocArray(zip(states, capitals));
auto statesByCapital = assocArray(zip(capitals, states));

If your data doesn't change for the lifetime of the program, that 
looks like a nice way to do it.

Re: Create class on stack

[Moritz Maxeiner via Digitalmars-d-learn]

On Saturday, 5 August 2017 at 17:08:32 UTC, Johnson Jones wrote:
using gtk, it has a type called value. One has to use it to get 
the value of stuff but it is a class. Once it is used, one 
doesn't need it.


Ideally I'd like to treat it as a struct since I'm using it in 
a delegate I would like to minimize unnecessary allocations. Is 
there any way to get D to allocate a class on the stack like a 
local struct?


The easy way is through std.typecons.scoped [1].
Here be dragons, though, because classes are reference types.

[1] https://dlang.org/phobos/std_typecons.html#.scoped

Re: returning D string from C++?

[Jeremy DeHaan via Digitalmars-d-learn]

On Saturday, 5 August 2017 at 20:17:23 UTC, bitwise wrote:
I have a Windows native window class in C++, and I need a 
function to return the window title.


[...]


As long as you have a reachable reference to the GC memory 
SOMEWHERE, the GC won't reclaim it. It doesn't have to be on the 
stack as long as it is reachable through the stack.

Re: gtkD load images

[ag0aep6g via Digitalmars-d-learn]

On 08/05/2017 10:30 PM, Mike Wey wrote:

On 05-08-17 15:23, Johnson Jones wrote:

On Saturday, 5 August 2017 at 12:51:13 UTC, Mike Wey wrote:

[...]
There are two issues here, you need to properly escape the slash: 
"C:a.jpg".

[...]

```
Pixbuf p = new Pixbuf(r"C:\\a.jpg");
```


Thanks. Why do I need 4 slashes? Is that standard with gtk because 
strings are interpreted twice or something? Seemed to work though.





Nothing specific to GTK but in D and other programing languages the \ is 
used as an escape character, so you can use special characters in your 
sting like `\n` for a newline. But this means you will need to use \\ to 
get an literal back slash.


I think you missed the point of the question.

In the end, the path should contain only one backslash. But with 
`"C:a.jpg"` and `r"C:\\a.jpg"` you get two. Why do you need two? 
Does the library do another round of escape sequence handling?

Re: gtkD window centering message up and no app on taskbar

[Mike Wey via Digitalmars-d-learn]

On 05-08-17 20:14, Johnson Jones wrote:
When trying to center the window. If one uses ALWAYS_CENTERED any 
resizing of the window is totally busted. CENTER also does not work. 
move(0,0) seems to not be relative to the main display. I'd basically 
like to center the window on the main display or at least be able to set 
coordinates properly. Windows sets (0,0) to be the lower left corner of 
the main display I believe. What happens is that the gtk window, when 
using 0,0 actually is like -1000,0 or something in windows coordinates 
and ends up on my secondary monitor.


When the app starts there's no taskbar icon. Luckily I still have the 
console shown but Eventually I'll need the taskbar. I'm not setting 
skipTaskBarHint, but I have tried both true and false without any 
difference.




gtk.Widget.translateCoordinates or gtk.Fixed could be useful for 
positioning the widgets.


Windows will only show the taskbar icon if you are not running the 
application from the console.


--
Mike Wey

Re: gtkD load images

[Mike Wey via Digitalmars-d-learn]

On 05-08-17 15:23, Johnson Jones wrote:

On Saturday, 5 August 2017 at 12:51:13 UTC, Mike Wey wrote:

On 03-08-17 21:56, Johnson Jones wrote:

If I do something like

import gdkpixbuf.Pixbuf;
Pixbuf.newFromResource("C:\\a.jpg");


There are two issues here, you need to properly escape the slash: 
"C:a.jpg".


And a.jpg is not a resource file, so you would use the Pixbuf 
constuctor to load an image file.


```
Pixbuf p = new Pixbuf(r"C:\\a.jpg");
```


Thanks. Why do I need 4 slashes? Is that standard with gtk because 
strings are interpreted twice or something? Seemed to work though.





Nothing specific to GTK but in D and other programing languages the \ is 
used as an escape character, so you can use special characters in your 
sting like `\n` for a newline. But this means you will need to use \\ to 
get an literal back slash.


https://dlang.org/spec/lex.html#double_quoted_strings

You can also use an wysiwyg string by using `r"` at the start so what 
you type is what you get.


https://dlang.org/spec/lex.html#wysiwyg

--
Mike Wey

Re: Create class on stack

[angel via Digitalmars-d-learn]

On Saturday, 5 August 2017 at 17:08:32 UTC, Johnson Jones wrote:
using gtk, it has a type called value. One has to use it to get 
the value of stuff but it is a class. Once it is used, one 
doesn't need it.


Ideally I'd like to treat it as a struct since I'm using it in 
a delegate I would like to minimize unnecessary allocations. Is 
there any way to get D to allocate a class on the stack like a 
local struct?


Emplace ?
https://dlang.org/phobos/std_conv.html#emplace

returning D string from C++?

[bitwise via Digitalmars-d-learn]

I have a Windows native window class in C++, and I need a 
function to return the window title.


So in D, I have this:

// isn't D's ABI stable enough to just return this from C++
// and call it a string in the extern(C++) interface? anyways..
struct DString
{
size_t length;
immutable(char)* ptr;
string toString() { return ptr[0..length]; }
alias toString this;
}

extern(C++) interface NativeWindow {
DString getTitle() const;
}

and in C++, this:

class NativeWindow
{
public:
struct DString {
size_t length;
const char* ptr;
};

virtual DString getTitle() const {
DString ret;
ret.length = GetWindowTextLength(_hwnd) + 1;
ret.ptr = (const char*)gc_malloc(ret.length, 0xA, NULL);
GetWindowText(_hwnd, (char*)ret.ptr, ret.length);
return ret;
}
};

So while it's not generally safe to _store_ pointers to D's GC 
allocated memory exclusively in C++, I've read that D's GC scans 
the stack, and getTitle() is being called from D(and so, is on 
that stack..right?). So is the string I'm returning safe from GC 
collection?


  Thanks

Re: Getting enum from value

[Matthew Remmel via Digitalmars-d-learn]

On Saturday, 5 August 2017 at 18:26:10 UTC, Kreikey wrote:
On Saturday, 5 August 2017 at 15:33:57 UTC, Matthew Remmel 
wrote:
I feel like I'm missing something, but there has to be an 
easier way to convert a value into an enum than switching over 
every possible value: i.e


[...]


Capitals c = cast(Capitals)"Chicago";
writeln(c);// Illinois


I'm annoyed that I didn't think of trying to cast it. That works 
great if the value exists in the enum. It does something weird if 
the value doesn't though. This is my test.d file:


import std.stdio;

enum Foo {
A = "AV",
B = "BV"
}

void main() {
Foo k = cast(Foo)"BV"; // Works and prints correctly

k = cast(Foo)"CV";
writeln("Type: ", typeid(k));  // Type: test.Foo
writeln("Value: ", k);   // Value: cast(Foo)CV
}

The output shows the type being the Foo enum but the value is 
'cast(Foo)CV'. I would of expected an error or exception to be 
thrown if it wasn't able to cast into an actual enum member. Is 
this something with how the enums are implemented under the hood?

Re: lambda function with "capture by value"

[Temtaime via Digitalmars-d-learn]

On Saturday, 5 August 2017 at 19:19:06 UTC, Simon Bürger wrote:

On Saturday, 5 August 2017 at 18:54:22 UTC, ikod wrote:

Maybe std.functional.partial can help you.


Nope.

int i = 1;
alias dg = partial!(writeln, i);
i = 2;
dg();

still prints '2' as it should because 'partial' takes 'i' as a 
symbol, which is - for this purpose - kinda like "by reference".


Anyway, I solved my problem already a while ago by replacing 
delegates with custom struct's that implement the 
call-operator. I started this thread just out of curiosity, 
because as I see it, the purpose of lambdas is pretty much to 
remove the need for such custom constructions.


This one works

void delegate()[3] dgs;
for(int i = 0; i < 3; ++i)
{
(k){ dgs[k] = {writefln("%s", k); }; }(i);
}

dgs.each!(a => a());

Re: lambda function with "capture by value"

[Simon Bürger via Digitalmars-d-learn]

On Saturday, 5 August 2017 at 18:54:22 UTC, ikod wrote:

Maybe std.functional.partial can help you.


Nope.

int i = 1;
alias dg = partial!(writeln, i);
i = 2;
dg();

still prints '2' as it should because 'partial' takes 'i' as a 
symbol, which is - for this purpose - kinda like "by reference".


Anyway, I solved my problem already a while ago by replacing 
delegates with custom struct's that implement the call-operator. 
I started this thread just out of curiosity, because as I see it, 
the purpose of lambdas is pretty much to remove the need for such 
custom constructions.

Re: lambda function with "capture by value"

[Simon Bürger via Digitalmars-d-learn]

On Saturday, 5 August 2017 at 18:54:22 UTC, ikod wrote:

On Saturday, 5 August 2017 at 18:45:34 UTC, Simon Bürger wrote:

On Saturday, 5 August 2017 at 18:22:38 UTC, Stefan Koch wrote:

[...]


No, sometimes I want i to be the value it has at the time the 
delegate was defined. My actual usecase was more like this:


void delegate()[3] dgs;
for(int i = 0; i < 3; ++i)
dgs[i] = (){writefln("%s", i); };


And I want three different delegates, not three times the 
same. I tried the following:


void delegate()[3] dgs;
for(int i = 0; i < 3; ++i)
{
int j = i;
dgs[i] = (){writefln("%s", j); };
}

I thought that 'j' should be considered a new variable each 
time around, but sadly it doesn't work.


Maybe std.functional.partial can help you.


Thanks. But std.functional.partial takes the fixed arguments as 
template parameters, so they must be known at compile-time. 
Anyway, I solved my problem already a while ago by replacing 
delegates with custom structures which overload the 
call-operator. I opened this thread just out of curiosity. Takes 
a couple lines more but works fine.

Re: lambda function with "capture by value"

[ikod via Digitalmars-d-learn]

On Saturday, 5 August 2017 at 18:45:34 UTC, Simon Bürger wrote:

On Saturday, 5 August 2017 at 18:22:38 UTC, Stefan Koch wrote:

[...]


No, sometimes I want i to be the value it has at the time the 
delegate was defined. My actual usecase was more like this:


void delegate()[3] dgs;
for(int i = 0; i < 3; ++i)
dgs[i] = (){writefln("%s", i); };


And I want three different delegates, not three times the same. 
I tried the following:


void delegate()[3] dgs;
for(int i = 0; i < 3; ++i)
{
int j = i;
dgs[i] = (){writefln("%s", j); };
}

I thought that 'j' should be considered a new variable each 
time around, but sadly it doesn't work.


Maybe std.functional.partial can help you.

Re: lambda function with "capture by value"

[Simon Bürger via Digitalmars-d-learn]

On Saturday, 5 August 2017 at 18:22:38 UTC, Stefan Koch wrote:

On Saturday, 5 August 2017 at 18:19:05 UTC, Stefan Koch wrote:

On Saturday, 5 August 2017 at 18:17:49 UTC, Simon Bürger wrote:
If a lambda function uses a local variable, that variable is 
captured using a hidden this-pointer. But this capturing is 
always by reference. Example:


int i = 1;
auto dg = (){ writefln("%s", i); };
i = 2;
dg(); // prints '2'

Is there a way to make the delegate "capture by value" so 
that the call prints '1'?


Note that in C++, both variants are available using
  [&]() { printf("%d", i); }
and
   [=]() { printf("%d", i); }
respectively.


No currently there is not.


and it'd be rather useless I guess.
You want i to be whatever the context i is a the point where 
you call the delegate.

Not at the point where you define the delegate.


No, sometimes I want i to be the value it has at the time the 
delegate was defined. My actual usecase was more like this:


void delegate()[3] dgs;
for(int i = 0; i < 3; ++i)
dgs[i] = (){writefln("%s", i); };


And I want three different delegates, not three times the same. I 
tried the following:


void delegate()[3] dgs;
for(int i = 0; i < 3; ++i)
{
int j = i;
dgs[i] = (){writefln("%s", j); };
}

I thought that 'j' should be considered a new variable each time 
around, but sadly it doesn't work.

Re: lambda function with "capture by value"

[Johnson Jones via Digitalmars-d-learn]

On Saturday, 5 August 2017 at 18:17:49 UTC, Simon Bürger wrote:
If a lambda function uses a local variable, that variable is 
captured using a hidden this-pointer. But this capturing is 
always by reference. Example:


int i = 1;
auto dg = (){ writefln("%s", i); };
i = 2;
dg(); // prints '2'

Is there a way to make the delegate "capture by value" so that 
the call prints '1'?


Note that in C++, both variants are available using
   [&]() { printf("%d", i); }
and
   [=]() { printf("%d", i); }
respectively.


There is, but it isn't pretty.

import std.stdio;

void main()
{
int i = 1;
int* n = null;
auto dg = (){ if (n is null) n = cast(int*)i; else writefln("%s", 
n); }; dg();

i = 2;
dg(); // prints '1'
}


1. I'm pretty sure that D creates the delegate "lazily" in the 
sense that the first call is what captures the variable. Hence, 
we must call it where we want to capture, not after the change 
occurs.


2. We use a temp local variable to act as a place holder. A 
singleton basically.


You might be able to wrap this up in some type of template that 
makes it easier to use but it does work.

Re: Getting enum from value

[Kreikey via Digitalmars-d-learn]

On Saturday, 5 August 2017 at 15:33:57 UTC, Matthew Remmel wrote:
I feel like I'm missing something, but there has to be an 
easier way to convert a value into an enum than switching over 
every possible value: i.e


[...]


Capitals c = cast(Capitals)"Chicago";
writeln(c);// Illinois

Re: lambda function with "capture by value"

[Stefan Koch via Digitalmars-d-learn]

On Saturday, 5 August 2017 at 18:19:05 UTC, Stefan Koch wrote:

On Saturday, 5 August 2017 at 18:17:49 UTC, Simon Bürger wrote:
If a lambda function uses a local variable, that variable is 
captured using a hidden this-pointer. But this capturing is 
always by reference. Example:


int i = 1;
auto dg = (){ writefln("%s", i); };
i = 2;
dg(); // prints '2'

Is there a way to make the delegate "capture by value" so that 
the call prints '1'?


Note that in C++, both variants are available using
  [&]() { printf("%d", i); }
and
   [=]() { printf("%d", i); }
respectively.


No currently there is not.


and it'd be rather useless I guess.
You want i to be whatever the context i is a the point where you 
call the delegate.

Not at the point where you define the delegate.

Re: lambda function with "capture by value"

[Stefan Koch via Digitalmars-d-learn]

On Saturday, 5 August 2017 at 18:17:49 UTC, Simon Bürger wrote:
If a lambda function uses a local variable, that variable is 
captured using a hidden this-pointer. But this capturing is 
always by reference. Example:


int i = 1;
auto dg = (){ writefln("%s", i); };
i = 2;
dg(); // prints '2'

Is there a way to make the delegate "capture by value" so that 
the call prints '1'?


Note that in C++, both variants are available using
   [&]() { printf("%d", i); }
and
   [=]() { printf("%d", i); }
respectively.


No currently there is not.

lambda function with "capture by value"

[Simon Bürger via Digitalmars-d-learn]

If a lambda function uses a local variable, that variable is 
captured using a hidden this-pointer. But this capturing is 
always by reference. Example:


int i = 1;
auto dg = (){ writefln("%s", i); };
i = 2;
dg(); // prints '2'

Is there a way to make the delegate "capture by value" so that 
the call prints '1'?


Note that in C++, both variants are available using
   [&]() { printf("%d", i); }
and
   [=]() { printf("%d", i); }
respectively.

gtkD window centering message up and no app on taskbar

[Johnson Jones via Digitalmars-d-learn]

When trying to center the window. If one uses ALWAYS_CENTERED any 
resizing of the window is totally busted. CENTER also does not 
work. move(0,0) seems to not be relative to the main display. I'd 
basically like to center the window on the main display or at 
least be able to set coordinates properly. Windows sets (0,0) to 
be the lower left corner of the main display I believe. What 
happens is that the gtk window, when using 0,0 actually is like 
-1000,0 or something in windows coordinates and ends up on my 
secondary monitor.


When the app starts there's no taskbar icon. Luckily I still have 
the console shown but Eventually I'll need the taskbar. I'm not 
setting skipTaskBarHint, but I have tried both true and false 
without any difference.

Re: Getting enum from value

[ag0aep6g via Digitalmars-d-learn]

On 08/05/2017 07:05 PM, ag0aep6g wrote:

E enumFromValue(E)(string s)


The type of `s` should probably be a template parameter as well.

Re: Getting enum from value

[ag0aep6g via Digitalmars-d-learn]

On 08/05/2017 05:33 PM, Matthew Remmel wrote:
I feel like I'm missing something, but there has to be an easier way to 
convert a value into an enum than switching over every possible value: i.e


enum Capitals {
 Indiana = "Indianapolis",
 Illinois = "Chicago",
 Ohio = "Columbus"
}

Capitals enumFromValue(string s) {
 switch (s) {
 case Capitals.Indiana:
 return Capitals.Indiana;
  case Capitals.Illinois:
 return Capitals.Illinois;
  case Capitals.Ohio:
 return Capitals.Ohio;
  default:
  throw new Exception(format("No Capitals enum member with 
value %s", s));

 }
}

int main() {
 Capitals c = enumFromValue("Chicago"); // works

 // I tried using std.conv, but it matches on the enum member name
 c = to!Capitals("Chicago") // fails, no member named Chicago
}

With how redundant the enumFromValue(string) implementation is, I would 
think there would be an easier way to do it. I'm sure you could use a 
mixin, a template, or std.traits. I was hoping there was a more 
'builtin' way to do it though. Something along the simplicity of:


int main() {
 Capitals c = Capitals("Chicago");
}

Any ideas?


As far as I know, there's no built-in way to do this. But you can 
simplify and generalize your `enumFromValue`:



enum Capitals
{
Indiana = "Indianapolis",
Illinois = "Chicago",
Ohio = "Columbus"
}

E enumFromValue(E)(string s)
{
import std.format: format;
import std.traits: EnumMembers;
switch (s)
{
foreach (c; EnumMembers!E)
{
case c: return c;
}
default:
immutable string msgfmt = "enum %s has no member with value %s";
throw new Exception(format(msgfmt, E.stringof, s));
}
}

void main()
{
auto c = enumFromValue!Capitals("Chicago");
assert(c == Capitals.Illinois);
}

Create class on stack

[Johnson Jones via Digitalmars-d-learn]

using gtk, it has a type called value. One has to use it to get 
the value of stuff but it is a class. Once it is used, one 
doesn't need it.


Ideally I'd like to treat it as a struct since I'm using it in a 
delegate I would like to minimize unnecessary allocations. Is 
there any way to get D to allocate a class on the stack like a 
local struct?

Re: Getting enum from value

[Matthew Remmel via Digitalmars-d-learn]

On Saturday, 5 August 2017 at 15:42:53 UTC, Rene Zwanenburg wrote:
On Saturday, 5 August 2017 at 15:33:57 UTC, Matthew Remmel 
wrote:

Any ideas?


You can use to! in std.conv:


import std.stdio;
import std.conv;

enum Foo
{
A = "A",
B = "B"
}

void main()
{
writeln("A".to!Foo);  
}


This only works because the enum name and the value are the same. 
Its actually converting on the enum name, which happens to be the 
same as the value. This doesn't work if the values is different:


enum Foo {
A = "AV",
B = "BV"
}

int main() {
writeln("AV".to!Foo); // Throws exceptions
return 0;
}

It looks like Temtaime's solution works:


enum Foo
{
A = "AV",
B = "BV",
C = "CV",
}



Foo K = [ EnumMembers!Foo ].find!(a => a == `BV`)[0];


I can probably make a template or something out of this to make 
the syntax simpler.

Re: Size of D bool vs size of C++ bool

[Jeremy DeHaan via Digitalmars-d-learn]

On Friday, 4 August 2017 at 20:38:16 UTC, Steven Schveighoffer 
wrote:

On 8/4/17 4:16 PM, Jeremy DeHaan wrote:
I'm trying to do some binding code, and I know that C++ bool 
isn't defined to be a specific size like D's bool. That said, 
can I assume that the two are the same size on the most 
platforms?


I shudder to think that D may work with a platform that doesn't 
consider it to be 1 byte :)


The only platforms I'm really interested in are Windows, 
Linux, OSX, iOS, FreeBSD, Android. The only thing that might 
throw me off is if there are some things that Linux or FreeBSD 
target where this is not the case, but these machines are 
probably out of the scope of my project.


I would say any platform that D currently supports, C++ bool is 
defined to be 1 byte.


The ldc/gdc guys would know better.

-Steve


Thanks, Steve. I was hoping this was the case and it will 
significantly simplify a lot of my binding code.


I'm curious to see what systems don't have a bool size of 1 byte, 
but perhaps I'll put a check in my CMake file and prevent the 
project from building if it isn't.

Re: gtk get actual pixel height of widget

[FoxyBrown via Digitalmars-d-learn]

On Saturday, 5 August 2017 at 15:23:15 UTC, Johnson Jones wrote:
I am trying to set positions of widgets automatically. e.g., I 
have a paned widget and I to set the position of the handle 
manually based on a percentage of the window. e.g., 0.5 will 
set the handle midway and both children will have the same 
height. I 0.2 will set it to to 20%.


[...]


Sorry, I think I was running my code before the window was 
actually being shown and I guess these values are not set until 
the actual display of the window.

Re: Getting enum from value

[Temtaime via Digitalmars-d-learn]

On Saturday, 5 August 2017 at 15:42:53 UTC, Rene Zwanenburg wrote:
On Saturday, 5 August 2017 at 15:33:57 UTC, Matthew Remmel 
wrote:

Any ideas?


You can use to! in std.conv:


import std.stdio;
import std.conv;

enum Foo
{
A = "A",
B = "B"
}

void main()
{
writeln("A".to!Foo);  
}


Are you fools ?
Did you ever read the post ?

I think this is a minimal solution:

enum Foo
{
A = "AV",
B = "BV",
C = "CV",
}

Foo K = [ EnumMembers!Foo ].find!(a => a == `BV`)[0];

Re: How to build GUI-based applications in D ?

[ashit via Digitalmars-d-learn]

thank you everybody for your time to answer my questions.

Re: How to build GUI-based applications in D ?

[ashit via Digitalmars-d-learn]

On Saturday, 5 August 2017 at 07:10:50 UTC, aberba wrote:
The DlangUI docs has you covered with everything you need to 
set it up both on the github README file or the github wiki.


Its just:

dub init PROJECT_NAME dlangui


This will create project and add dlangui as dependency. 
Creating a project requires Internet connection to download the 
dlangui package. You may also add dlangui as a dependency in 
the project's dub.json file.


thank you aberba

ok, so this is useless to me.
i want something fully functional stand-alone tools.
i have no internet connection there.

Re: Getting enum from value

[Rene Zwanenburg via Digitalmars-d-learn]

On Saturday, 5 August 2017 at 15:33:57 UTC, Matthew Remmel wrote:

Any ideas?


You can use to! in std.conv:


import std.stdio;
import std.conv;

enum Foo
{
A = "A",
B = "B"
}

void main()
{
writeln("A".to!Foo);  
}

Re: Getting enum from value

[Stefan Koch via Digitalmars-d-learn]

On Saturday, 5 August 2017 at 15:33:57 UTC, Matthew Remmel wrote:
I feel like I'm missing something, but there has to be an 
easier way to convert a value into an enum than switching over 
every possible value: i.e


[...]


What you want is already in the standard library.
std.conv.to can convert strings to enums and back.

Re: gtk: get property

[Johnson Jones via Digitalmars-d-learn]

On Saturday, 5 August 2017 at 15:19:43 UTC, Gerald wrote:

On Saturday, 5 August 2017 at 15:08:21 UTC, Johnson Jones wrote:
I am trying to get the handle size of panned. Not sure if I'm 
doing it right but


[...]


I'm using this in Tilix:

Value handleSize = new Value(0);
paned.styleGetProperty("handle-size", handleSize);


Awesome! Thanks! I didn't see that method in the list of 1000's 
of function in Visual D ;/ Figured everything that was a getter 
started with get.

Getting enum from value

[Matthew Remmel via Digitalmars-d-learn]

I feel like I'm missing something, but there has to be an easier 
way to convert a value into an enum than switching over every 
possible value: i.e


enum Capitals {
Indiana = "Indianapolis",
Illinois = "Chicago",
Ohio = "Columbus"
}

Capitals enumFromValue(string s) {
switch (s) {
case Capitals.Indiana:
return Capitals.Indiana;
 case Capitals.Illinois:
return Capitals.Illinois;
 case Capitals.Ohio:
return Capitals.Ohio;
 default:
 throw new Exception(format("No Capitals enum member 
with value %s", s));

}
}

int main() {
Capitals c = enumFromValue("Chicago"); // works

// I tried using std.conv, but it matches on the enum member 
name

c = to!Capitals("Chicago") // fails, no member named Chicago
}

With how redundant the enumFromValue(string) implementation is, I 
would think there would be an easier way to do it. I'm sure you 
could use a mixin, a template, or std.traits. I was hoping there 
was a more 'builtin' way to do it though. Something along the 
simplicity of:


int main() {
Capitals c = Capitals("Chicago");
}

Any ideas?

gtk get actual pixel height of widget

[Johnson Jones via Digitalmars-d-learn]

I am trying to set positions of widgets automatically. e.g., I 
have a paned widget and I to set the position of the handle 
manually based on a percentage of the window. e.g., 0.5 will set 
the handle midway and both children will have the same height. I 
0.2 will set it to to 20%.


I want it to retain this proportion when the window is resized.

The problem is I cannot get get the paned widgets actual 
height(nor the handle size).


paned.getHeight() returns -1.

If I use the main window's height, things go wonky because, I 
guess the border size and title bar size skew the calculations.


I'm still learning this api and how it all functions and works. 
Some things are not so obvious nor logical. getHeight should 
return the height. If -1 means "leave it up to the internals" 
then there should be some other height function that works like 
getActualHeight() but there isn't or I can't find anything that 
works.


If I do


writeln(mainPaned.getAllocatedHeight());

writeln(mainPaned.getChild1.getAllocatedHeight());  

writeln(mainPaned.getChild2.getAllocatedHeight());



then I get something like

800
1
1

where 800 is the height I used to set the window using

auto width = 1000, height = 800;
mainWindow.resize(width,height);

which, I'd expect it to actually be smaller as either it doesn't 
take in to account the titlebar or the resize function above is 
not for the full application window.

Re: gtk: get property

[Gerald via Digitalmars-d-learn]

On Saturday, 5 August 2017 at 15:08:21 UTC, Johnson Jones wrote:
I am trying to get the handle size of panned. Not sure if I'm 
doing it right but


[...]


I'm using this in Tilix:

Value handleSize = new Value(0);
paned.styleGetProperty("handle-size", handleSize);

gtk: get property

[Johnson Jones via Digitalmars-d-learn]

I am trying to get the handle size of panned. Not sure if I'm 
doing it right but


Value value = new Value();
paned.getProperty("handle-size", value);


GLib-GObject-CRITICAL **: g_object_get_property: assertion 
'G_IS_VALUE (value)' failed


or I get stuff like

GLib-GObject-WARNING **: g_object_get_property: object class 
'GtkStyle' has no property named 'handle-size'


if I do

mainPaned.getStyle().getProperty("handle-size", value);

I haven't been able to figure out how to get it.


I've also tried

mainPaned.getStyle().getStyleProperty(...

but the first parameter is a GType which is suppose to be the 
widget type yet I am getting value types like INT BOOl, etc.


Not sure if there are two types of GTypes

enum GType : size_t
{
INVALID = 0<<2,
NONE = 1<<2,
INTERFACE = 2<<2,
CHAR = 3<<2,
UCHAR = 4<<2,
BOOLEAN = 5<<2,
INT = 6<<2,
UINT = 7<<2,
LONG = 8<<2,
ULONG = 9<<2,
INT64 = 10<<2,
UINT64 = 11<<2,
ENUM = 12<<2,
FLAGS = 13<<2,
FLOAT = 14<<2,
DOUBLE = 15<<2,
STRING = 16<<2,
POINTER = 17<<2,
BOXED = 18<<2,
PARAM = 19<<2,
OBJECT = 20<<2,
VARIANT = 21<<2,
}

If that what I'm suppose to use then not sure which one I use for 
Paned ;)

Re: Remove instance from array

[Igor Shirkalin via Digitalmars-d-learn]

On Wednesday, 5 July 2017 at 16:04:16 UTC, Jolly James wrote:

On Wednesday, 5 July 2017 at 15:56:45 UTC, Igor Shirkalin wrote:

On Wednesday, 5 July 2017 at 15:48:14 UTC, Jolly James wrote:
On Wednesday, 5 July 2017 at 15:44:47 UTC, Igor Shirkalin 
wrote:

On Wednesday, 5 July 2017 at 15:30:08 UTC, Jolly James wrote:

WhatEver[] q = [];

[...]

auto i = new WhatEver();
q[] = i;



How does one remove that instance 'i'?


What exactly do you want to remove? After a[]=i your array 
contain a lot of references to 'i'.


I would like to know how works: removing
 - the first
 - and all
references to 'i' inside the 'q'.


Perhaps, for all references to i it should look like:
a = a.filter!(a => a !is i).array;


Thank you! :)


But why a containers so complicated in D?

In C# I would go for a generic List, which would support 
structs and classes, where I simply could call '.Remove(T 
item)' or '.RemoveAt(int index)'. I would know how this works, 
because the method names make sense, the docs are straight 
forward.


Here in D everything looks like climbing mount everest. When 
you ask how to use D's containers you are recommended to use 
dynamic arrays instead. When you look at the docs for 
std.algorithm, e.g. the .remove section, you get bombed with 
things like 'SwapStrategy.unstable', asserts and tuples, but 
you aren't told how to simply remove 1 specific element.


I don't know c sharp, but I can tell everything about c++ and 
python. To climb a everest in python you have to know almost 
nothing, in c++ you have to know almost everything. In D you have 
to be smarter, you do not need to climb a everest but you have to 
know minimum to do that. Spend a year in learning and get the 
best result in minutes).

Re: Fix gtkD api display

[Mike Wey via Digitalmars-d-learn]

On 04-08-17 17:24, Gerald wrote:

On Friday, 4 August 2017 at 15:08:27 UTC, Mike Wey wrote:
Improving the documentation is something i want to do but there are 
always some more important things to do. Like the Questions/Issues you 
posted earlier.


So unless somebody volunteers it won't happen anytime soon.


Mike I had contributed the makeddox.sh script awhile ago, it generates 
much nicer documentation then candydocs in my IHMO and includes a nice 
search box. If there is something lacking in it that needs to be 
improved before it can be used let me know and I'll do the work.


The only issue with it that I am aware of is you need to manually copy 
the public ddox css into the generated folder. I didn't see an easy way 
to determine it's location automatically.


One issue is the shear size of the generated documentation, though the 
current version of ddox no longer generates a ton of unused files 
bringing the size down from 15-20GB to a mere 2GB.


So it has at leased become manageable to host it on the VPS that hosts 
gtkd.org.


Now remains figuring out setting up the proper redirects on the server, 
and a few personal preferences about ddox:


The need to go trough the empty module page when browsing the 
documentation. For a lot / most? functions the complete documentation is 
in the overview defeating the purpose of the one page per artifact.

And im not a big fan of the one page per artifact style of documentation.

--
Mike Wey

Re: gtkD load images

[Johnson Jones via Digitalmars-d-learn]

On Saturday, 5 August 2017 at 12:51:13 UTC, Mike Wey wrote:

On 03-08-17 21:56, Johnson Jones wrote:

If I do something like

import gdkpixbuf.Pixbuf;
Pixbuf.newFromResource("C:\\a.jpg");


There are two issues here, you need to properly escape the 
slash: "C:a.jpg".


And a.jpg is not a resource file, so you would use the Pixbuf 
constuctor to load an image file.


```
Pixbuf p = new Pixbuf(r"C:\\a.jpg");
```


Thanks. Why do I need 4 slashes? Is that standard with gtk 
because strings are interpreted twice or something? Seemed to 
work though.

Re: GtkD custom theme on Windows

[Mike Wey via Digitalmars-d-learn]

On 04-08-17 05:06, Andres Clari wrote:
I've made a linux program with GtkD, and so far, it's been pretty 
awesome, however I'm thinking about porting it to Windows also, but the 
Adwaita theme is too fugly, and cringy, so I'd want to use a compatible 
theme, which is supposed to be doable.


What would be the way to go to make a GtkD app use a custom GTK theme in 
Windows?
I tried this in the past, but never succeeded following documentation 
found online.



I didn't try it myself but it should be something like this:

-Download a theme from gnome-look.org
-Extract the theme to: C:\\Program Files\Gtk-Runtime\share\themes
-Edit C:\\Program Files\Gtk-Runtime\etc\gtk-3.0\settings.ini and add:

```
gtk-theme-name = Name_of_Theme
```

--
Mike Wey

Re: gtkD load images

[Mike Wey via Digitalmars-d-learn]

On 03-08-17 21:56, Johnson Jones wrote:

If I do something like

import gdkpixbuf.Pixbuf;
Pixbuf.newFromResource("C:\\a.jpg");


There are two issues here, you need to properly escape the slash: 
"C:a.jpg".


And a.jpg is not a resource file, so you would use the Pixbuf constuctor 
to load an image file.


```
Pixbuf p = new Pixbuf(r"C:\\a.jpg");
```

--
Mike Wey

Re: Bug in gtkd?

[Mike Wey via Digitalmars-d-learn]

On 03-08-17 23:11, Johnson Jones wrote:

On Thursday, 3 August 2017 at 21:00:17 UTC, Mike Wey wrote:

On 03-08-17 22:40, Johnson Jones wrote:
Ok, so, I linked the gtk to the msys gtk that I installed before when 
trying to get glade to work and it worked!


seems that msys is much more up to date than anything else as it just 
works(I need to remember than in the future).


The problem I see is this:

When I get ready to release my app to the public, I can't expect them 
to all have to install msys and build.


msys seems to clump everything together and I don't know what files I 
need to extract to be able to bundle everything together.


Any ideas how to solve that problem? At least now I can move ahead 
and actually make some progress on my app.


Would still be nice to get the x86 vs x64 issue resolved so I don't 
have to keep switching between the two for testing purposes. Since 
Visual D was just patched to handle x64 BP's I guess I can stay with 
that for now.




I'll try to build and test some new installers tomorrow that will 
include the loaders.


Thanks. Could you take a look at the loading image thread I started when 
you get time? I can't seem to get an image to load even though it seems 
straight forward.


These are the pixbufs I'm using

mingw32/mingw-w64-i686-gdk-pixbuf2 2.36.6-2 [installed]
 An image loading library (mingw-w64)
mingw64/mingw-w64-x86_64-gdk-pixbuf2 2.36.6-2 [installed]
 An image loading library (mingw-w64)

in x64 it crashes completely without an exception though... which is why 
I want an easy way to switch between the two architectures... since x64 
seems to be more unstable than x86 but sometimes it's the reverse, and 
ultimately I'll want to release in x64.


Also, do I ever need to rebuild gdk when changing gtk installations? 
Does it ever grab anything from them at compile time or is it all at 
runtime?


The new installers are available: https://gtkd.org/Downloads/runtime/

You don't need to rebuild GtkD when changing GTK installations, it does 
it all at runtime.


--
Mike Wey

Re: How to build GUI-based applications in D ?

[Jacob Carlborg via Digitalmars-d-learn]

On 2017-08-01 17:45, ashit wrote:


thank you James

i should try that.
i was always enjoy the pure and efficiency of C. that made me stubborn
to learn java.


Just to be clear, there's no Java code in DWT. Everything is ported to D.

--
/Jacob Carlborg

Re: How to build GUI-based applications in D ?

[aberba via Digitalmars-d-learn]

On Thursday, 3 August 2017 at 10:02:19 UTC, ashit wrote:

On Tuesday, 1 August 2017 at 16:12:45 UTC, Dukc wrote:

On Tuesday, 1 August 2017 at 15:18:12 UTC, ashit wrote:
i couldn't set control's width and height (Button widget) 
shows error. maybe it works a different way.


1. Try layoutHeight/width. Remember to set it for the main 
widget too, not just the children of it.


2. DlangUI is not intended to define sizes in pixels as a 
standard practice. Instead, use layouts and layout sizes. This 
is intended to courage you to make your program 
resolution-agnostic.


But I'm a beginner at this topic too. Take these with a grain 
of salt


thank you Dukc

it worked, i should adapt with this different naming style. (as 
comparing to C#)

[yesterday]
but today, when i went to create another project, it failed.
i get this message:

D:\ashit\documents\D\simpled>dub init simpled dlangui
Couldn't find package: dlangui.

it works without the "dlangui" option, but then when i execute 
run command:


D:\ashit\documents\D\simpled>dub run
Performing "debug" build using dmd for x86.
simpled ~master: building configuration "application"...
source\app.d(2,8): Error: module dlangui is in file 'dlangui.d' 
which cannot be

read
import path[0] = source
import path[1] = C:\dmd2\windows\bin\..\..\src\phobos
import path[2] = C:\dmd2\windows\bin\..\..\src\druntime\import
dmd failed with exit code 1.

this is the path i have extracted the dlangui files:

D:\ashit\software\D Compiler\DlangUI\dlangui-master

how to define dlangui for DUB?


The DlangUI docs has you covered with everything you need to set 
it up both on the github README file or the github wiki.


Its just:

dub init PROJECT_NAME dlangui


This will create project and add dlangui as dependency. Creating 
a project requires Internet connection to download the dlangui 
package. You may also add dlangui as a dependency in the 
project's dub.json file.