[Python-Dev] Multiple Inclusion of Header Files (original) (raw)

David Abrahams dave@boost-consulting.com
11 Oct 2002 09:26:42 -0400

Neal Norwitz <neal@metaslash.com> writes:

On Fri, Oct 11, 2002 at 07:48:52AM -0400, Guido van Rossum wrote: > > > is there any reason why these files: > > > graminit.h > > > patchlevel.h > > > pyconfig.h (aka pyconfig.h.in) > > > > > > don't protect against being included multiple times? > > > > I think they cannot possibly be included multiple times in a correct > > application, since a correct application does not directly include > > them, anyway. > > But that's true of any .h file that's included by Python.h, isn't it? > And there's only a handful of .h files that Python.h doesn't include...

I don't really think there is much to be gained by adding protection. It's unlikely the files would be included directly by an application. Even if the files are included multiple times, the worst that should happen is a redefined warning.

Ahem. Don't forget that C++ applications may need to read these files. The rules about redefinition are different in C++ IIRC.

So, if these files /really/ don't need to be #included directy by an application, that's fine...

However, I note that Boost.Python has to #include <patchlevel.h> because we have to apply workarounds before #including <Python.h> for certain versions of Python, so I wouldn't say that it's very unrealistic to think applications might need these files separately.

-- David Abrahams * Boost Consulting dave@boost-consulting.com * http://www.boost-consulting.com