On Wednesday 23 March 2005 21:14, Paul Eggert wrote:
> > +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
>
> Remove "very".
> Use English spacing after sentences; i.e., two spaces after the period.
>
> > +support for an external library (e.g., the readline library); if the
> > user +did not specify neither @option{--with-readline} nor
>
> did not specify -> specified
>
> > + [support fancy command line editing <default=check>])],
>
> Defaults should be in square brackets, not angle brackets.
Thanks for the suggestions, they are included below.
> One more-general comment: there is a lot of duplication here in the
> three examples. Can you rewrite it to give just one example, and
> then briefly discuss the modifications needed for the other two cases?
> That would make it easier to follow.
Yes, I thought about it. However, in a way it is justified:
the whole point behind this proposal is that there is not a clear indication
on the "standard" way to use AC_ARG_WITH. This is not just a teorethical
statement, but is reflected in real world situations in a manifold of
non-standard uses of that macro that really hurts us distributors, for the
reasons discussed previously on this list.
I think there's a gain in being as clear as possible when presenting the macro
to the user in the autoconf manual, even if there's a bit of redundancy.
Anyway, the patch below is just a suggestion. Feel free to take only the bits
that you find appropriate for the manual.
Gregorio
Index: doc/autoconf.texi
===================================================================
RCS file: /cvsroot/autoconf/autoconf/doc/autoconf.texi,v
retrieving revision 1.884
diff -u -B -r1.884 autoconf.texi
--- doc/autoconf.texi 23 Mar 2005 01:01:58 -0000 1.884
+++ doc/autoconf.texi 23 Mar 2005 22:25:00 -0000
@@ -13313,6 +13313,81 @@
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 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
+specified 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})
@@ -13383,6 +13458,10 @@
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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