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Properly formatting the `help strings' which are used in
AC_ARG_WITH (see section Working With External Software) and AC_ARG_ENABLE
(see section Choosing Package Options) can be challenging. Specifically, you want
your own `help strings' to line up in the appropriate columns of
`configure --help' just like the standard Autoconf `help
strings' do. This is the purpose of the AC_HELP_STRING macro.
Expands into an help string that looks pretty when the user executes
`configure --help'. It is typically used in AC_ARG_WITH
(see section Working With External Software) or AC_ARG_ENABLE (see section Choosing Package Options). The following example will make this clearer.
AC_DEFUN(TEST_MACRO,
[AC_ARG_WITH(foo,
AC_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)])
Please note that the call to AC_HELP_STRING is unquoted.
Then the last few lines of `configure --help' will appear like
this:
--enable and --with options recognized: --with-foo use foo (default is NO)
The AC_HELP_STRING macro is particularly helpful when the
left-hand-side and/or right-hand-side are composed of macro
arguments, as shown in the following example.
AC_DEFUN(MY_ARG_WITH,
[AC_ARG_WITH([$1],
AC_HELP_STRING([--with-$1], [use $1 (default is $2)]),
ac_cv_use_$1=$withval, ac_cv_use_$1=no),
AC_CACHE_CHECK(whether to use $1, ac_cv_use_$1, ac_cv_use_$1=$2)])
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