hgext/commitextras.py

bookflow: new extension for bookmark-based branching

This extension should be helpful for feature branches - based workflows.
At my company we first considered branches, but weren't sure about creating a lot of permanent objects.
We tried bookmarks, but found some scenarios to be difficult to control.

The main problem, was the active bookmark being moved on update.
Disabling that made everything a lot more predictable.

Bookmarks move on commit, and updating means switching between them.

The extension also implements a few minor features to better guide the workflow:
  - hg bookmark NAME can be ambiguous (create or move), unlike hg branch. The extension requires -rev to move.
  - require an active bookmark on commit.
  - some bookmarks can be protected (like @), useful for teams, that require code reviews.
  - block creation of new branches.

The initial implementation requires no changes in the core, but it does rely on some implementation details.
I thought it may be useful to discuss the functionality first, and then focus making the code more robust.

Differential Revision: https://phab.mercurial-scm.org/D4312

# commitextras.py
#
# Copyright 2013 Facebook, Inc.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

'''adds a new flag extras to commit (ADVANCED)'''

from __future__ import absolute_import

import re

from mercurial.i18n import _
from mercurial import (
    commands,
    error,
    extensions,
    registrar,
    util,
)

cmdtable = {}
command = registrar.command(cmdtable)
testedwith = 'ships-with-hg-core'

usedinternally = {
    'amend_source',
    'branch',
    'close',
    'histedit_source',
    'topic',
    'rebase_source',
    'intermediate-source',
    '__touch-noise__',
    'source',
    'transplant_source',
}

def extsetup(ui):
    entry = extensions.wrapcommand(commands.table, 'commit', _commit)
    options = entry[1]
    options.append(('', 'extra', [],
        _('set a changeset\'s extra values'), _("KEY=VALUE")))

def _commit(orig, ui, repo, *pats, **opts):
    if util.safehasattr(repo, 'unfiltered'):
        repo = repo.unfiltered()
    class repoextra(repo.__class__):
        def commit(self, *innerpats, **inneropts):
            extras = opts.get(r'extra')
            for raw in extras:
                if '=' not in raw:
                    msg = _("unable to parse '%s', should follow "
                            "KEY=VALUE format")
                    raise error.Abort(msg % raw)
                k, v = raw.split('=', 1)
                if not k:
                    msg = _("unable to parse '%s', keys can't be empty")
                    raise error.Abort(msg % raw)
                if re.search('[^\w-]', k):
                    msg = _("keys can only contain ascii letters, digits,"
                            " '_' and '-'")
                    raise error.Abort(msg)
                if k in usedinternally:
                    msg = _("key '%s' is used internally, can't be set "
                            "manually")
                    raise error.Abort(msg % k)
                inneropts[r'extra'][k] = v
            return super(repoextra, self).commit(*innerpats, **inneropts)
    repo.__class__ = repoextra
    return orig(ui, repo, *pats, **opts)