accees messages by filename

ChangeLog

@@ -3,6 +3,10 @@
 
 version 3.009:
 
+	Improvements:
+	- for file-per-message based folders, you can now address the message
+	  via its filename. rt.cpan.org#132823 [Alexander Adolf]
+
 version 3.008: Fri  4 Oct 08:34:32 CEST 2019
 
 	Fixes:

lib/Mail/Box/Dir.pm

@@ -166,7 +166,19 @@ sub folderToDirectory($$)
     $dir;
 }
 
-#-------------------------------------------
+sub storeMessage($)
+{   my ($self, $message) = @_;
+    $self->SUPER::storeMessage($message);
+    my $fn = $message->filename or return $message;
+    $self->{MBD_by_fn}{$fn} = $message;
+}
+
+=method messageInFile $filename
+Returns the folder message which is found the indicated C<filename>.  This
+may be useful when some external tool reports filename to be opened.
+=cut
+
+sub messageInFile($) { $_[0]->{MBD_by_fn}{$_[1]} }
 
 =method readMessageFilenames $directory