Using ACE_CACHE_CHECK with ACE_ARG_ENABLE/ACE_ARG_WITH?

[J.T. Conklin]

The autoconf manual has the following example for AS_HELP_STRING:

    AC_DEFUN([TEST_MACRO],
    [AC_ARG_WITH([foo],
                 AS_HELP_STRING([--with-foo],
                                [use foo (default is NO)]),
                 [ac_cv_use_foo=$withval], [ac_cv_use_foo=no])
    AC_CACHE_CHECK([whether to use foo],
                   [ac_cv_use_foo], [ac_cv_use_foo=no])])

I've seen this idiom of using AC_CACHE_CHECK after AC_ARG_ENABLE and
ACE_ARG_WITH elsewhere, but I do not really understand what benefits
caching brings.  For example, in the above ac_cv_use_foo is going to
be set one way or the other before the call to AC_CACHE_CHECK, so the
COMMANDS-TO-SET-IT will never be invoked.  

If the point is to print a message, why not use something like:

    AC_MSG_CHECKING([whether to use foo])
    AC_MSG_RESULT($ac_cv_use_foo)

?

    --jtc

-- 
J.T. Conklin