Paul Eggert <eggert@cs.ucla.edu> schrieb am Sa., 21. Nov. 2015 um 01:28 Uhr:

> Philipp Stephani wrote:
> > Why, that's how malloc also behaves.
>
> Yes, of course. But this part of malloc's behavior is so painful that
> Emacs code
> typically never invokes malloc directly; it uses xmalloc, which is
> guaranteed to
> return non-null. Many modules will have needs similar to Emacs itself in
> that
> respect, and it would be better if they didn't have to reinvent this
> so-common
> wheel.
>

But what should the interface be? There are only three possibilities in C:
return a sentinel value, crash, longjmp. Crashing prevents modules from
doing their own error handling or degrading gracefully. longjmp is not
possible in general because arbitrary C (and especially C++) code isn't
prepared for it. So the sentinel value is the only option. This is also
consistent with all the other environment functions that return a pointer.