Re: gec: Is it possible to specify a signature for a external C call?

Berend de Boer wrote:
>     Eric> The fact that it works with SmartEiffel and ISE Eiffel is just
>     Eric> luck in my opinion.
> 
> It works, because they emit a prototype. That had to be coded, so it's
> not luck.

The luck is that it's not specified anywhere in the standard
and you might have no prototype if you specify a header file
that does not contain such prototype.

>     Eric> Does it work as well when you add assertions to these
>     Eric> external routines?
> 
> Yes. The created prototypes are just for the called external function.

What I meant is that if there are assertions, a wrapper needs to
be generated. So my fear was that they would generate a prototype
for the wrapper and not for the external function. But perhaps
they don't generate such wrapper.

> For ISE it generates the prototype in a .c file:
> 
>   extern EIF_REAL_64 posix_difftime(EIF_INTEGER_32, EIF_INTEGER_32);
> 
> 
> If I add a header with:
> 
> 		external "C use <time.h>"
> 
> No such prototype is created.
> 
> So their behaviour is intentional and it allows everyone to link to
> libraries without having to know how to write header files (or having to
> distribute them if you distribute your C code).

I'll do like ISE, but I still think that it is not right
and works because of luck. Or if you prefer, it does not
work in some cases because of lack of luck (e.g. when you
specify a header file that does not contain a prototype
for your routine).

-- 
Eric Bezault
mailto:ericb-D6Qt/9opevxWk0Htik3J/[email protected]
http://www.gobosoft.com