Re: MERGE: bsescm2cxx

[Tim Janik <tim janik lanedo com>]

On 13.05.2011 17:11, Stefan Westerfeld wrote:
> > * For sfi_glue_gc_add(), please investigate if changing
> >    the second argument to (void(*free_func)(void*)) is likely to
> >    reduce casts. The reason the second funciton pointer argument is
> >    just void* is convenience in C, but were're moving away from that
> >    so it doesn't make sense to keep convenince C stuff if it makes
> >    our C++ life harder.
>
> I can reduce the number of casts in shell/bsescm* by changing the signature,
> however there is quite a bit of C code that either will not compile at all or
> will compile with warnings if I do this (for instance in sfi/sfiglue.c or the
> generated beast-gtk/bstgenapi.c), so overall a lot of new casts need to be
> added elsewhere. I'd suggest to delay this change until more of the remaining
> code is already C++ified.

Hm, if we go like this then we end up with lots of C++-ified code that
needs fixing after we've turned everything into C++. I.e. essentially
demanding a 2 phase approach, which I'd like to avoid since it could
allmost double our work. We should avoid any approach that forces us to
introduce either a lot of C or a lot of useless C++ casts. One way
is to port sfiglue along with the code you did. Another is the 
following, if something is just an issue on the language layer (i.e. not 
affecting ABI or semantics), I'd rather see us special case C++ vs. C in 
some very few selected places, that allow easy cleanups. E.g.:
#ifdef __cplusplus
void sfi_glue_gc_add (void(*)(void*));
#else /* !__cplusplus */
void sfi_glue_gc_add (void*);	// FIXME: remove C-legacy
#endif /* __cplusplus */

This is a very minor thing to fix after the move (and it works because 
global extern "C" functions in C++ have the same symbol names as C 
functions) *and* it's easy to spot by later grepping for "FIXME",
possibly even "C-legacy".

>     Cu... Stefan


--

Yours sincerely,
Tim Janik

---
http://lanedo.com/~timj/ - Founder and CEO of Lanedo GmbH.
Free software author and contributor on various projects.