X11 binding, XGetWindowProperty, and different behaviour for similar code between D and C++ (D fails)

[Fawzi Mohamed]

On 2009-04-03 19:33:21 +0200, "Simon Gomizelj" <simongmzlj at gmail.com> said:

> On Thu, 02 Apr 2009 09:59:55 -0400, Jarrett Billingsley  
> <jarrett.billingsley at gmail.com> wrote:
> 
>> On Fri, Apr 3, 2009 at 4:40 AM, Simon Gomizelj <simongmzlj at gmail.com>  wrote:
>>> On Fri, 03 Apr 2009 04:09:25 -0400, Simon Gomizelj  <simongmzlj at gmail.com>
>>> wrote:
>>> [...]
>> My best guess is that you've translated those X11 function headers
>> incorrectly.  Perhaps you've used a D long where you shouldn't have.
>> A D long is 64 bits, while a C long is 32, at least on 32-bit
>> platforms.  If you were to pass a 64-bit value where it was expecting
>> a 32-bit one, the params would be in all the wrong places.  But this
>> is just speculation, since I don't know what your bindings look like.
> 
> Yeah, thats it exactly, which is annoying because since I downloaded 
> this  binding I just assumed it was done right 8-).
> 
> extern (C):
> extern int XGetWindowProperty(
>      Display*    /* display */,
>      Window      /* w */,
>      Atom        /* property */,
>      long        /* long_offset */,  <-- should be int
>      long        /* long_length */,  <-- should be int
>      Bool        /* delete */,
>      Atom        /* req_type */,
>      Atom*       /* actual_type_return */,
>      int*        /* actual_format_return */,
>      uint*       /* nitems_return */,
>      uint*       /* bytes_after_return */,
>      ubyte**     /* prop_return */
> );
> 
> Since their are no occurences of long longs I just did a search and  
> replace across the whole file for longs to ints

actually the correct thing is to use c_long and c_ulong for that, c 
long on 64 bit platform is 64 bit...

I think that typically long should have the same size as a pointer, I 
even think that something along these lines is in the standard, but I 
am not 100% sure.

anyway D c_long should correspond to c long. tango defines it in 
tango.stdc.config, phobos probably in std.c.config (or something 
similar I did not check)

Fawzi