pick: improve compatibility.

The traditional component matching syntax, `--COMP STRING', is
accepted, provided at least one of the following conditions is met:

1. The word `COMP' contains at least one capital letter;
2. The word `COMP' ends with a colon;
3. Standard input is not connected to a terminal.

* mh/mh_getopt.c (mh_help_hook): New global variable.
(mh_help): Call mh_help_hook, if set.
* mh/mh_getopt.h (mh_help_hook): New extern.
* mh/pick.c (doc): Update.
(opt_handler): Remove ARGP_KEY_ERROR case.
(pick_help_hook): New function.
(main): Convert any instance of `--comp string' to
`--component=comp --pattern=string', if comp contains a
capital letter or ends with a colon, or fd 0 is not connected
to terminal.
* doc/texinfo/mu-mh.texi: Document changes to pick.

1 files changed, 14 insertions, 5 deletions

diff --git a/doc/texinfo/mu-mh.texi b/doc/texinfo/mu-mh.texi
index dc8567aae..b04a34c0f 100644
--- a/doc/texinfo/mu-mh.texi
+++ b/doc/texinfo/mu-mh.texi
@@ -332,11 +332,20 @@ The @code{rmmproc} profile component is not used.
 
 @item pick
 
-The non-standard command line syntax @option{--@var{field}
-@var{string}}), where @var{field} is any string, is deprecated. It is
-recognized only if @command{pick} is called from within another
-program, so that existing application continue to work. Please use the
-following syntax instead:
+The command line syntax @option{--@var{component} @var{string}}) is
+recognized only if at least one of the following conditions is met:
+
+@itemize @bullet
+@item The word @var{component} contains at least one capital letter.
+E.g. @option{--User-Agent Mailutils}.
+
+@item The word @var{component} ends with a colon, as in
+@option{user-agent: Mailutils}.
+
+@item Standard input is not connected to a terminal.
+@end itemize
+
+The GNU syntax for component matching is:
 
 @smallexample
 pick --component @var{field} --pattern @var{string}