Subj : Re: How to pass class-member function to pthread_create(....)?
To   : comp.programming.threads
From : Jedrzej Dudkiewicz
Date : Tue Jul 19 2005 05:17 pm

> > We use C headers and C libraries in C++ code. The only way to achieve it
in
> > C++ is to declare function passed to this libraries as extern "C".
>
> Thats simply not true. It is NOT the ONLY way, sorry. Just a sample
> from C++ standard (§25.4):
>
> extern "C" void qsort(void* base, size_t nmemb, size_t size,
>                         int (*compar)(const void*, const void*));
>
> extern "C++" void qsort(void* base, size_t nmemb, size_t size,
>                           int (*compar)(const void*, const void*));
>
> Another solution could be to make pthread_create not extern "C" in
> header (just default) and provide two version of it in the library -
> one for C and one for C++. And thats need to be done only in compiler
> where C++ and C functions use different calling conventions.

Now, I don't know what you want. You said:
> I am sorry, but I would like to see what POSIX says about C linkage in
> pthread_create, not your comments on that. Can you make a quote?

Standard says: Function prototypes must be provided for use with an ISO C
compiler.

I assume, that if interface (function prototypes) is in C, passed data MUST
be C-compatible. Library can be implemented in java or python, but it must
provide C interface.

You also wrote:

> You have to know that
> your C library compiler code is compatible with C++ compiler generated
> code anyway.

No. Your C++ compiler must be compatible with C library compiler. Not the
other way around.

> And you can know if it is safe to call extern "C++"
> linkage from the C library as well.

Maybe, but it's not required by any standard, so you can't count on it.

JD

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