On Friday 18 February 2005 15:56, Stepan Kasal wrote:
> I have a few comments. Mostly aesthetics, but also fixing some bugs in
> your examples (underquoted AS_HELP_STRING, for example):
>
> ...
Thanks for your help, Stepan.
Here's the new patch, after I applied your suggestions:
Index: doc/autoconf.texi
===================================================================
RCS file: /cvsroot/autoconf/autoconf/doc/autoconf.texi,v
retrieving revision 1.879
diff -u -B -r1.879 autoconf.texi
--- doc/autoconf.texi 15 Feb 2005 06:40:21 -0000 1.879
+++ doc/autoconf.texi 19 Feb 2005 18:22:13 -0000
@@ -13222,6 +13222,78 @@
You should format your @var{help-string} with the macro
@code{AS_HELP_STRING} (@pxref{Pretty Help Strings}).
+
+The following example shows how to use the @code{AC_ARG_WITH} macro in
+a very common situation. You want to let the user decide whether to enable
+support for an external library (e.g., the readline library); if the user
+did not specify neither @option{--with-readline} nor
+@option{--without-readline}, you want to enable support for readline only
+if the library is available on the system.
+
+@c FIXME: Remove AS_IF when the problem of AC_REQUIRE within `if' is solved.
+@example
+AC_ARG_WITH(readline,
+ [AS_HELP_STRING(--with-readline,
+ [support fancy command line editing <default=check>])],
+ [],
+ with_readline=check)
+LIBREADLINE=
+AS_IF([test "x$with_readline" != xno],
+ [AC_CHECK_LIB(readline, main,
+ [AC_SUBST(LIBREADLINE, "-lreadline -lncurses")
+ AC_DEFINE_UNQUOTED(HAVE_LIBREADLINE, 1, [Define if you have libreadline])
+ ],
+ [if test "x$with_readline" != xcheck; then
+ AC_MSG_FAILURE([--with-readline was given, but test for readline failed])
+ fi
+ ], -lncurses)])
+@end example
+
+The next example shows how to use @code{AC_ARG_WITH} to give the user the
+possibility to enable support for the readline library, in case it is still
+experimental and not well tested, and is therefore disabled by default.
+
+@c FIXME: Remove AS_IF when the problem of AC_REQUIRE within `if' is solved.
+@example
+AC_ARG_WITH(readline,
+ [AS_HELP_STRING(--with-readline,
+ [enable experimental support for readline <default=disabled>])],
+ [],
+ with_readline=no)
+LIBREADLINE=
+AS_IF([test "x$with_readline" != xno],
+ [AC_CHECK_LIB(readline, main,
+ [AC_SUBST(LIBREADLINE, "-lreadline -lncurses")
+ AC_DEFINE(HAVE_LIBREADLINE, 1, [Define if you have libreadline])
+ ],
+ [AC_MSG_FAILURE([--with-readline was given, but test for readline failed])],
+ -lncurses)])
+@end example
+
+The last example shows how to use @code{AC_ARG_WITH} to give the user the
+possibility to disable support for the readline library, given that it is
+an important feature and that it should be enabled by default.
+
+@c FIXME: Remove AS_IF when the problem of AC_REQUIRE within `if' is solved.
+@example
+AC_ARG_WITH(readline,
+ [AS_HELP_STRING(--without-readline,
+ [disable support for readline <default=enabled>])],
+ [],
+ with_readline=yes)
+LIBREADLINE=
+AS_IF([test "x$with_readline" != xno],
+ [AC_CHECK_LIB(readline, main,
+ [AC_SUBST(LIBREADLINE, "-lreadline -lncurses")
+ AC_DEFINE(HAVE_LIBREADLINE, 1, [Define if you have libreadline])
+ ],
+ [AC_MSG_FAILURE([test for readline failed, use --without-readline if you want to force readline support off])],
+ -lncurses)])
+@end example
+
+These three examples can be easily adapted to the case where
+@code{AC_ARG_ENABLE} should be preferred to @code{AC_ARG_WITH} (see
+@ref{Package Options}).
@end defmac
@defmac AC_WITH (@var{package}, @var{action-if-given}, @ovar{action-if-not-given})
@@ -13292,6 +13364,10 @@
You should format your @var{help-string} with the macro
@code{AS_HELP_STRING} (@pxref{Pretty Help Strings}).
+
+See the examples suggested with the definition of @code{AC_ARG_WITH}
+(@pxref{External Software}) to get an idea of possible utilizations of
+@code{AC_ARG_ENABLE}.
@end defmac
@defmac AC_ENABLE (@var{feature}, @var{action-if-given}, @ovar{action-if-not-given})
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