Re: AS_CASE vs case/esac

[Ralf Wildenhues]

* NightStrike wrote on Thu, Mar 13, 2008 at 09:20:06PM CET:
> Should AS_CASE 
> (http://www.gnu.org/software/autoconf/manual/autoconf.html#index-AS_005fCASE-1116)
> always be used instead of case/esac inside configure.ac, some local
> package m4 script, or AC_DEFUN macros?

Most of the time that is purely an aesthetic question.

It however matters if, inside AS_CASE arguments, you put
AC_DEFUN'ed macros which themselves AC_REQUIRE other macros.
They will then be expanded outside of the AS_CASE construct.

Example:

AC_INIT
AC_DEFUN([FOO], [echo foo])
AC_DEFUN([BAR], [AC_REQUIRE([FOO])
                 echo bar])
x=zork
AS_CASE([$x], [y*], [BAR])


will print 'foo' because FOO will be expanded outside of the AS_CASE.

Note that with AS_IF of Autoconf's 2.61 and newer, the same holds
(before 2.61, AS_IF was not m4_defun'ed, only m4_define'd, so the
expansion of required macros was not pushed outside of it).

Hope that helps.

Cheers,
Ralf