Re: [PATCH] Fix use of ENABLE_NLS (which is not always defined)

[Grégoire Sutre]

Eric Blake wrote:
> 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.

I see.  And the compiled file should be the same if the compiler
performs (even simple) dead-code elimination.

> 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.

I agree that functions can be difficult to read when they contain #if
conditions.  However, these cannot be avoided when the types of the
function's local variables depend on them.

> 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.

Good to know, thanks!

Grégoire