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Re: how to prefix definitions in config.h

From: Guido Draheim
Subject: Re: how to prefix definitions in config.h
Date: Mon, 18 Mar 2002 10:49:50 +0100

Es schrieb Clinton Roy:
> > > my_config.h: config.h
> > >         sed 's/#define /#define MY_/; s/#undef /#undef MY_/' <config.h >$@
> It would appear I can air my dirty code :)
> We define some of our own defines, that are already prefixed, so we
> have to take care of the case of double prefixing. We also wrap the
> header in an `#ifndef PREFIX_CONFIG_H; #define PREFIX_CONFIG_H ;
> #endif' so we don't have to worry about multiple inclusion.
> Finally:
> config.h: _config.h
>         echo "#ifndef PREFIX_CONFIG_H" > $(output)
>         echo "#define PREFIX_CONFIG_H" >> $(output)
>         sed -e 's/#define /#define PREFIX_/' \
>             -e 's/#undef /#undef PREFIX_/' \
>             -e 's/PREFIX_PREFIX_/PREFIX_/' < $(input) >> $(output)
>         echo "#endif /* PREFIX_CONFIG_H */" >> $(output)
> Pretty icky, but it does get the job done.

yes, that was my first shot too ;-) - it's seems to be the canonical
answer to the problem we have to handle and it seems to be a very
common approach to get the job done. 

just a hint: after doing some projects with the first attempt of
the prefix-macro, I noticed it would be better to prefix lowercase
entries in config.h with a lowercased prefix, so that for example
off_t maps to my_off_t and const maps to my_const. These examples
are also the case for wrapping the generated my-config.h into another
my-conf.h that looks like:

#ifdef _MSC_VER
#include <msvc-conf.h>
#include <my-config.h>
#ifndef my_off_t
#define my_off_t off_t

after here, all the library headers include my-conf.h and use the
my_off_t entry for the function declarations.

well, one might call these just cosmetics but I think it looks
better, or perhaps just *hmmm* more professional *giggle*.

have fun,
-- guido                          
GCS/E/S/P C++/++++$ ULHS L++w- N++@ d(+-) s+a- r+@>+++ y++ 5++X- (geekcode)

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