Re: C++ header files

On Tue, Jun 24, 2008 at 08:27:59PM -0400, David Chin wrote:
> The __cplusplus macro is part of the ISO C++ standard, defined
> precisely because the standards committee knew (presumably) that there
> would be people who would want to use their old plain C stuff.
>
> Similarly, ISO C has the macro __STDC__ defined.

Both true, but irrelevant.  The C++ coders have extern "C" so
that they can use their old C stuff.  The __cplusplus define
is so that you can *pretend* that C code is C++ code.

> See here:  http://docs.sun.com/app/docs/doc/819-5267/bkaep?a=view
>
> So, it is more than just idiom. It's required of a standards-compliant compiler.

No, it's just idiom, because these are C headers that we're
talking about.

Done properly, the C++ code would have:

extern "C" {
#include <atlas.h>
}

and then everyone would be happy, and there would be no need for
spurious #ifdef bracketing in the C header.

The problem is the whole notion that a header file can
meaningfully be both a C header file and a C++ header file.  If
you replace C++ by, say, Eiffel in that sentence, the statement
gets a bit more obvious.  

C compilers mightn't see it, but C coders will, and they'll
cringe every time.  I know that I do.

Cheers,

--
Andrew

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