Re: Passing C pointers through guile

["Kjetil S. Matheussen" <k.s.matheussen@notam02.no>]

On Fri, 11 Jul 2008, Greg Troxel wrote:

> "Kjetil S. Matheussen" <k.s.matheussen@notam02.no> writes:
>
>> Also, various types of non-gc pointers are stored in integers in
>> all of the rt-*.scm files in http://snd.cvs.sourceforge.net/snd/cvs-snd/
>> and many others (xg.c, etc.). It would be horribly idiotic
>> to write smurf's for all of those, or at least a common smurf, when a
>> single integer is enough.
>
> What fraction of these uses are actually correct?  Have people run this
> code on Windows 64 (which is LLP64, but on which long is 32 bits),
> sparc64, and alpha.

All of them are correct. The alternative would be messier code.
The code in question doesn't run on those platforms anyway,
since there's a lot of strict linux stuff. However, I don't
the storage of pointers in unsigned longs (which is a perfectly
legal thing to do if done correctly), would pose any problem
for running it on other hardware.


>  I'm always worried when people store pointers in
> integers - it's IMHO basically a wrong thing to do.
>

In many situations, like the one above, it's a perfectly fine thing
to do, and also the only sane option. Of course, you must know what you 
are doing.