[Monotone-devel] automate sync display branches?

[Stephen Leake]

I'm currently using a variation of examples/display_branches.lua to show
what branches are transfered during a sync.

This works nicely when sync is run from a shell command line, but it's
not so nice when run from automate stdio. I'm trying to enhance Emacs
DVC to support a nice sync interface; it will display which workspaces
need updating after a sync.

First, the messages are written directly to stderr, which screws up the
stdio packetizing. 

After fixing that, the messages are in the progress stream, where they
are not easy to parse.

I'd like them to be on stdout, in basic_io format.

So I wrote another variant of display_branches.lua that does that. But I
only want that version when running a sync command in a stdio session. I
tried specifying an 'rcfile' option for the sync command; it was
accepted but silently ignored. rcfiles are only processed in
monotone.cc:cpp_main, when the 'automate stdio' command is run.

It would be nice if we got an error for an rcfile option on a stdio
command; not clear how to accomplish that.

We could try processing rcfiles for each stdio command, but I suspect
that would not be good. For example, unless we can 'undo' each rcfile
after each command, the effects would be cumulative, and thus impossible
to trust. Unless we rerun _all_ rcfiles for each command; that would be
consistent with running from a shell command line. Still messy to
maintain separate lists of "original" and "new" rcfiles, so we know
which ones to run.

Better would be to not use rcfiles for this purpose, which means adding
C++ code to 'automate sync' to output the branch names, enabled by an
option --output-branch-names.

Before I start on that, I'm looking for feedback.

-- 
-- Stephe