Hi,
on looking at CFFI from a porters point of view, I find what I consider a design failure. Namely, C functions are used without declaring them or even with fake declarations.
First of all, every time you call a function with foreign-funcall you have to supply the types of the arguments. The aliasing of all pointer types to :pointer means that type information is lost. Not all pointer type are equivalent, because some types have alignment restrictions.
Supplying the argument types is extremely tricky in some cases and might not be enough type information. For example, int f1(int i, ...) is not the same function as int f2(int i, int j) even though when we invoke f1(1, 2) the (2) is coerced to type int.
The information about "..." is taken cared of by DEFCFUN, but not by FOREIGN-FUNCALL. That may seem useless but really, it is not the same thing to call f1 and f2, because the C compiler does produce different assembly code. For instance, using AMD64, in the first case it has to push the arguments on the stack, while in the second case everything goes into registers Similar things happen with a PPC backend.
My current approach to coerce all functions to the first form is really a hack. And I wonder whether this design will survive newer architectures to come.
Regards,
Juanjo
-- Max-Planck-Institut für Quantenoptik Hans-Kopfermann-Str. 1, Garching, D-85748, Germany Phone: +49 89 32905 345 Fax: +49 89 32905 336 http://www.mpq.mpg.de/Theorygroup/CIRAC/