On 03/17/2010 06:58 PM, Grégoire Sutre wrote: > Just out of curiosity: is there a reason for this behavior of > AC_CHECK_DECLS, which, quoting the manual, is unlike the other > ‘AC_CHECK_*S’ macros?
Yes - it looks cleaner to write code like: if (CONDITION) do_something (); than #if CONDITION do_something (); #endif but that only works if CONDITION is always defined to 0 or 1. In general, we prefer to avoid #if inside function bodies; it is easier to read code where all the #if have been factored out to file scope level and function bodies are straight-line code. Newer autoconf macros follow this style, and gnulib continues it for most macros defined by gnulib. And even for the older autoconf macros which did not follow this paradigm, it's not too hard to do: #ifndef CONDITION # define CONDITION #endif at the top of the file, to once again keep #if out of function bodies. -- Eric Blake ebl...@redhat.com +1-801-349-2682 Libvirt virtualization library http://libvirt.org
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