Mainline branch defaults

[Stephen J. Turnbull]

Ben Finney writes:
 > "Stephen J. Turnbull" <stephen at xemacs.org> writes:

 > > It's not really a criticism of "Bazaar".  It is a criticism of a
 > > particular default.  Maybe, given the logic and the reports of users,
 > > we should consider changing that default?
 > 
 > Default for what, though? When Bazaar creates a branch, the default
 > should *not* be ‘--append-revisions-only’. That's IMO only a sensible
 > default for a mainline branch;

That's not clear to me.  Although bzr does handle bidirectional merges
well (as such things go ;-), one would prefer to avoid them when
possible.  If your feature branch workflow does not involve syncing to
(ie, merging from) mainline, then --append-revisions-only is TRT for
the feature branch, too.  A lot of recommended workflows have the
property that merges flow in one direction; in those cases,
--append-revisions-only is a safety feature for all branches.

OTOH, if you have a long-lived feature branch that needs to be synced
to mainline regularly, then in some sense I think it is a mainline
branch, but you want --append-revisions-only *off*.

 > and how does Bazaar know that's the case unless told?

It doesn't.  That's why I'm suggesting a different default for the
option, not something that is always inferred.

 > And, if we're going to need to tell Bazaar that a particular branch is a
 > mainline, how is that different from the manual setting of the existing
 > option ‘--append-revisions-only’?

I think that the only time you want --append-revisions-only *off* is
precisely when you have multiple mainlines, and you need to merge in
both directions.  Even then, there's probably one (or more) "stable"
mainlines that should have --append-revisions-only *on*.