[RFC] ssoma-mda: Use the email subject as the commit message

["W. Trevor King" <wking@tremily.us>]

This is more interesting than just using 'mda' all the time, but it's
harder to setup proper quoting around the message without using
third-party Perl modules (e.g. IPC::Run or String::ShellQuote).  This
proof-of-concept patch just assumes the subject doesn't contain
single-quotes (').  This patch also doesn't handle the empty/missing
subject case, which should probably fall back to '<no subject>' or
some such.

I'm fine dropping support for older Gits here, and just using the -m
option to commit-tree.  That landed with 96b8d93a (commit-tree: teach
-m/-F options to read logs from elsewhere, 2011-11-09) in Git v1.7.9,
which was released over 2.5 years ago on 2012-01-27.

It would also be useful (I think) to set the GIT_AUTHOR_NAME,
GIT_AUTHOR_EMAIL, and GIT_AUTHOR_DATE environment variables from the
message header before committing.  I know how to do that using
Python's subprocess module, but I don't know the Perl incantation.
---
Is there any interest in a Python port of ssoma?  The subprocess
handling in Perl's standard libraries is not my favorite ;).  I expect
we could handle all of ssoma without leaving Python's standard
libraries.  For an example of a related Perl -> Python rewrite that I
just landed, see nmbug [1,2,3].

Cheers,
Trevor

[1]: http://notmuchmail.org/nmbug/
[2]: http://thread.gmane.org/gmane.mail.notmuch.general/19189
     id:cover.1412359989.git.wking@tremily.us
[3]: http://article.gmane.org/gmane.mail.notmuch.general/19272
     id:2a9f3e7423fe3ab95c2c6fbd6047aed935b6463b.1412703127.git.wking@tremily.us

 lib/Ssoma/Git.pm | 5 ++---
 lib/Ssoma/MDA.pm | 3 ++-
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/lib/Ssoma/Git.pm b/lib/Ssoma/Git.pm
index 2211893..e8d4cf6 100644
--- a/lib/Ssoma/Git.pm
+++ b/lib/Ssoma/Git.pm
@@ -266,10 +266,9 @@ sub commit_index {
 	my @cmd = qw/git commit-tree/;
 	push @cmd, $tree;
 	push @cmd, '-p', $parent if $parent;
+	push @cmd, '-m', "'$message'";
 
-	# git commit-tree -m didn't work in older git versions
-	$message =~ /\A\w+\z/ or die "message must be \\w+ only\n";
-	my $commit = $self->qx_sha1("echo $message |". join(' ', @cmd));
+	my $commit = $self->qx_sha1(join(' ', @cmd));
 
 	# update the ref
 	@cmd = (qw/git update-ref/, $ref, $commit);
diff --git a/lib/Ssoma/MDA.pm b/lib/Ssoma/MDA.pm
index 02816a5..6b58b43 100644
--- a/lib/Ssoma/MDA.pm
+++ b/lib/Ssoma/MDA.pm
@@ -102,7 +102,8 @@ sub append {
 		my $id = $git->simple_to_blob($simple);
 		$gii->update('100644', $id, $path);
 	}
-	$git->commit_index($gii, 0, $ref, "mda");
+	my $subject = $simple->header("Subject");
+	$git->commit_index($gii, 0, $ref, $subject);
 }
 
 # the main entry point takes an Email::Simple object
-- 
2.1.0.60.g85f0837