Changeset Evolution Plan

This page is intended for developers

Proposition for safe rewriting of mercurial history. This will have a close relationship with StatesPlan

• Presentation of the concept: http://hg-lab.logilab.org/doc/mutable-history/html/

• Related experimental extension (usable): http://bitbucket.org/marmoute/mutable-history/overview

Older materials

• Initial presentation at Copenhagen: http://public.octopoid.net/talk.pdf

• First tutorial written by Parren: http://arrenbrecht.ch/mercurial/evolution/

1. Core principle

• Store and explicit relation between new and old version of rewritten changeset.
• This relation should *not* be part of the changeset (should not alter the hash).
• People must be able to collaborate on evolving changeset

2. Additional idea

• Save delta in a real changeset.
• This relation should be exchangeable without rewritten changeset.
• Easily allow other extension to manipulate such relation (and to hook on such operation)

3. Situation that should be handled

• Rewriting content of a changeset,
• delete/kill a changeset.
• split a single changeset in multiple one,
• collapse multiple changeset in single one,
• change changeset order,
• adding (eg pulling) a changeset evolution that conflict with another one.
• adding (or adding in general ) new changesets on a one which already evolved (or evolving a changeset that have descendant)