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* doc/autoconf.texi (Prerequisite Macros): Dedocument AC_PROVIDE.

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(Coding Style): Move some into...
(Macro Definitions): here.
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@ -1,3 +1,9 @@
2000-07-19 Akim Demaille <akim@epita.fr>
* doc/autoconf.texi (Prerequisite Macros): Dedocument AC_PROVIDE.
(Coding Style): Move some into...
(Macro Definitions): here.
2000-07-19 Akim Demaille <akim@epita.fr>
The --help message should have paragraphs starting with a title,

79
doc/autoconf.texi
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@ -5891,23 +5891,42 @@ the order in which macros are called (@pxref{Prerequisite Macros}).
An Autoconf macro definition looks like this:
@example
AC_DEFUN(@var{macro-name}, [@var{macro-body}])
AC_DEFUN(@var{macro-name}, @var{macro-body})
@end example
@noindent
The square brackets here do not indicate optional text: they should
literally be present in the macro definition to avoid macro expansion
problems (@pxref{Quoting}). You can refer to any arguments passed to
the macro as @samp{$1}, @samp{$2}, etc.
You can refer to any arguments passed to the macro as @samp{$1},
@samp{$2}, etc. @xref{Definitions,, How to define new macros, m4.info,
GNU m4}, for more complete information on writing M4 macros.
To introduce comments in M4, use the builtin @code{dnl}; it causes
@code{m4} to discard the text through the next newline. It is not
needed between macro definitions in @file{acsite.m4} and
@file{aclocal.m4}, because all output is discarded until @code{AC_INIT}
is called.
Be sure to quote properly both the @var{macro-body} @emph{and} the
@var{macro-name}, to avoid any problems if the macro happens to be
already defined.
Any macro should have a header comment which gives its prototype, and a
short documentation. When arguments have default values, display them
in the prototype. For instance:
@example
# AC_MSG_ERROR(ERROR, [EXIT-STATUS = 1])
# --------------------------------------
define([AC_MSG_ERROR],
[@{ _AC_ECHO([configure: error: $1], 2); exit m4_default([$2], 1); @}])
@end example
Comments about the macro should be left in the header comment. Most
other comments should make their way into @file{configure}, hence just
keep using @samp{#} to introduce comments.
@cindex @code{dnl}
If you have some very special comments about pure M4 code, comments
which make no sense in @file{configure} and in the header comment, then
use the builtin @code{dnl}: it causes @code{m4} to discard the text
through the next newline.
Keep in mind that @code{dnl} is rarely needed to introduce comments,
rather it is useful to get rid of the newlines behind macros which
produce no output, such as @code{AC_REQUIRE}.
@xref{Definitions,, How to define new macros, m4.info, GNU m4}, for more
complete information on writing M4 macros.
@node Macro Names, Quoting, Macro Definitions, Writing Macros
@section Macro Names
@ -6496,22 +6515,6 @@ SOME_CHECK
You are encouraged to put all the @code{AC_REQUIRE}s at the beginning of
the macros. You can use @code{dnl} to avoid the empty line they leave.
An alternative to using @code{AC_DEFUN} is to use @code{define} and call
@code{AC_PROVIDE}. Because this technique does not prevent nested
messages, it is considered obsolete.
@defmac AC_PROVIDE (@var{this-macro-name})
@maindex PROVIDE
Record the fact that @var{this-macro-name} has been called.
@var{this-macro-name} should be the name of the macro that is calling
@code{AC_PROVIDE}. An easy way to get it is from the M4 builtin
variable @code{$0}, like this:
@example
AC_PROVIDE([$0])
@end example
@end defmac
@node Suggested Ordering, , Prerequisite Macros, Dependencies Between Macros
@subsection Suggested Ordering
@ -6694,20 +6697,10 @@ purpose. With the @code{s} command, the preferred separator is @samp{/}
unless @samp{/} itself is used in the command, in which case you should
use @samp{,}.
When defining a macro, quote the name being defined. If the macro is
never @code{AC_REQUIRE}'d nor @code{AC_REQUIRE}'s, use @code{define}.
In case of doubt, use @code{AC_DEFUN}. Include the prototype of the
macro in its header comments. When arguments have default values,
display them in the prototype. For instance:
@example
# AC_MSG_ERROR(ERROR, [EXIT-STATUS = 1])
# --------------------------------------
define([AC_MSG_ERROR],
[@{ _AC_ECHO([configure: error: $1], 2); exit m4_default([$2], 1); @}])
@end example
All the @code{AC_REQUIRE} should be at the beginning of the macro,
@xref{Macro Definitions}, for details on how to define a macro. If the
macro is never @code{AC_REQUIRE}'d nor @code{AC_REQUIRE}'s, use
@code{define}. In case of doubt, use @code{AC_DEFUN}. All the
@code{AC_REQUIRE} should be at the beginning of the macro,
@code{dnl}'ed.
Unless the macro is short, try to leave the closing @samp{])} at the