in complex workflows

Alexander Solovyov

• Paylogic employee
• Python developer for 5 years
• Mercurial contributor for 3 years
• ...and author and contributor to several other projects

• Everybody has write access to central repository
• Code review post factum
• Centralized VCS, linear history

• Too much conflicts

• Post factum never works

• Unfinished work hard to manage

World has invented a great model for developer interaction:

Open Source

• Core team (gatekeepers)
• Contributors (developers)
• Disconnected development

• Developers submit changes
• Gatekeepers review them
• Changes are merged in main line

• Experience exchange
• Prevent sad code
• Collective code ownership

• Changesets in repository instead of patches
• Zero effort branching and merging
• Full history of development
• Total control of situation

• Started in April 2005
• Very fast
• 94% Python, 6% C (30k lines)
• Simple and clean Python API for extensions

• Track features with branches in a single repository
• Have developers' repositories on a server
• Tag branches with bookmarks (or use named branches)
• Use all hg's power to help you

• Embedded web-server for viewing and sharing
• Zero configuration

project> hg serve
listening at http://hostname:8000/ (bound to *:8000)

# this requires zeroconf extension enabled
~> hg paths
zc-hostname-project = http://192.168.1.2:8000/

• What do I have in my branch?

project> hg log -r 'ancestors(branchname) - ancestors(master)'

• What is not merged yet?

project> hg log -r 'bookmark() - ancestors(master)' --template '{bookmarks}\n'

• Much more powerful than that: http://selenic.com/hg/help/revsets

• Suddenly need a fix in an older release?
• Use hg transplant!
• Merge will take care

• color
• pager
• progress
• schemes (url shortcuts)
• rebase (uh-huh)

• Very simple and clean
• Extensive
  • hooks
  • helpers for wrapping functions
  • adding commands
• Improve your workflow with writing extensions

def bookpush(orig, ui, repo, dest=None, **opts):
    if '.' in opts.get('bookmark', ()) and repo._bookmarkcurrent:
        n = opts['bookmark'].index('.')
        opts['bookmark'][n] = repo._bookmarkcurrent
    return orig(ui, repo, dest, **opts)

def uisetup(ui):
    extensions.wrapcommand(commands.table, 'push', bookpush)

And suddenly you don't need to copy-paste:

> hg push -B . # instead of "-B bookmark-name"

• check you're in the right branch
• check you're not resolving file with conflicts
• start working on a case
• stop working on a case, merge with target branch, submit changes

Automate and structure it

It's the time for them. :)