Add support for suffixing parameters with '_append', and corresponding docs.

This allows the option of constructing parameter values accumulatively
rather than overriding existing parameter values.
(cherry picked from commit aa3caf53a9cb35ee3d0e4173ed44e964c6b8b5ab)

diff --git a/mr b/mr
index b503fa710b16cfb1f8c176aa044f34df311a5ebf..ba0cf0a8ac6ba4dc78a0b4f384ac29ecf89fe468 100755 (executable)
--- a/mr
+++ b/mr
@@ -415,9 +415,14 @@ to keep track of and remember to delete old repositories.
 
 =item lib
 
-The "lib" parameter can specify some shell code that will be run before each
-command, this can be a useful way to define shell functions for other commands
-to use.
+The "lib" parameter can specify some shell code that will be run
+before each command, this can be a useful way to define shell
+functions for other commands to use.  Unlike most other parameters,
+this can be specified multiple times, in which case the chunks of
+shell code are accumulatively concatenated together.  This is
+particularly useful because it allows the user to build a library of
+shell functions defined in the [DEFAULT] section scattered across
+various mr modules (files referenced by an C<include> directive).
 
 =item fixups
 
@@ -447,6 +452,11 @@ the action that is performed for a given version control system, you can
 override these VCS specific actions. To add a new version control system,
 you can just add VCS specific actions for it.
 
+As with the C<lib> parameter, if a parameter is suffixed with
+C<_append>, its value is concatenated to the existing value of the
+parameter for that config block, rather than overwriting it.  In this
+way, actions such as C<fixup> can be constructed accumulatively.
+
 =head1 UNTRUSTED MRCONFIG FILES
 
 Since mrconfig files can contain arbitrary shell commands, they can do
@@ -1287,8 +1297,8 @@ sub loadconfig {
                        if ($section eq 'ALIAS') {
                                $alias{$parameter}=$value;
                        }
-                       elsif ($parameter eq 'lib') {
-                               $config{$dir}{$section}{lib}.=$value."\n";
+                       elsif ($parameter eq 'lib' or $parameter =~ s/_append$//) {
+                               $config{$dir}{$section}{$parameter}.="\n".$value."\n";
                        }
                        else {
                                $config{$dir}{$section}{$parameter}=$value;