=============================

Mutable History For Mercurial

=============================

Evolve Extension

=================

This package supplies the ``evolve`` extension for Mercurial,

**The full implementation of the changeset evolution concept is still in

progress.**  Please subscribe to the `evolve-testers mailing list

<https://www.mercurial-scm.org/mailman/listinfo/evolve-testers>`_ to stay up to

date with changes.

This extension:

* enables the "changeset evolution" feature of Mercurial core,

* provides a set of commands to mutate your history,

* issues several warning messages when troubles from some mutable appears in

  your repository,

* provides an ``hg evolve`` command to deal with such "troubles",

* improves performance of obsolescence marker exchanges and discovery during

  push and pull.

Documentation

-------------

We recommend reading the documentation first. An online version is

available here:

    https://www.mercurial-scm.org/doc/evolution/

How to Install

==============

Using Pip

---------

You can install the latest evolution version usin pip::

    $ pip install --user hg-evolve

Then just enable it in you hgrc::

    $ hg config --edit # adds the two line below:

    [extensions]

    evolve =

From Source

-----------

To install a local version from source::

    $ hg clone https://www.mercurial-scm.org/repo/evolve/

    $ cd evolve

    $ pip install --user .

Then just enable it in you hgrc::

    $ hg config --edit # adds the two line below:

    [extensions]

    evolve =

Documentation lives in ``doc/``.

Server Only Setup

=================

It is possible to enable a smaller subset of the extensions aimed at server

serving repository. It skips the additions of the new commands and local UI

messages that might add performance overheads. To use the server only

extension, install the package and use::

    $ hg config --edit # adds the two line below:

    [extensions]

    evolve.serveronly =

Extension Purpose

=================

The goal of this extension is to provide an appropriate place for code and

concept related to changeset evolution to mature. In this extension we allow

for hackier code, unlocking quick experimentation and faster iterations.

In addition, the evolve extensions support a wider set of Mercurial version,

allowing us to reach a larger user base for feedback. The Evolve extension is

not tight to the Mercurial release cycle and can release new feature and bug

fix at a higher rate if necessary.

Once a concept is ready enough, its implementation is moved into Mercurial

core. The maturation period helped us to get a clearer picture of what was

needed. During the upstreaming process, we can use this clearer picture to

clean up the code and upgrade it to an appropriate quality for Mercurial core.

Python 3 support

================

Mercurial announced beta support for Python 3 starting with its 5.0 release.

Since 9.1.0, ``evolve`` has beta support for Python 3.6+.

Support will stay in beta while Mercurial's support for Python 3 remains in

beta and until it is a bit more battle-tested.

How to Contribute

=================

Discussion happens on the #hg-evolve IRC on freenode_.

.. _freenode: https://freenode.net/

Bugs are to be reported on the mercurial's bug tracker (component: `evolution`_):

.. _evolution: https://bz.mercurial-scm.org/buglist.cgi?component=evolution&query_format=advanced&resolution=---

The recommended way is to create Merge Request on

https://foss.heptapod.net/mercurial/evolve. To do so, create an account and

request access. You'll then be able to create topic based merge request.

Alternatively, you can use the patchbomb extension to send email to `mercurial

devel <https://www.mercurial-scm.org/mailman/listinfo/mercurial-devel>`_.

Please make sure to use the evolve-ext flag when doing so. You can use a

command like this::

    $ hg email --to mercurial-devel@mercurial-scm.org --flag evolve-ext --rev '<your patches>'

For guidelines on the patch description, see the `official Mercurial guideline`_.

.. _`official Mercurial guideline`: https://mercurial-scm.org/wiki/ContributingChanges#Patch_descriptions

Please don't forget to update and run the tests when you fix a bug or

add a feature. To run the tests, you need a working copy of Mercurial,

say in $HGSRC::

    $ cd tests

    $ python $HGSRC/tests/run-tests.py

When certain blocks of code need to cope with API changes in core Mercurial,

they should have comments in the ``hg <= x.y (commit hash)`` format. For

example, if a function needs another code path because of changes introduced in

02802fa87b74 that was first included in Mercurial 5.3, then the comment should

be::

    # hg <= 5.2 (02802fa87b74)

See also tests/test-check-compat-strings.t.

Branch policy

-------------

The evolve tests are highly impacted by changes in core. To deal with this, we

use named branches.

There are two main branches: "stable" and "default". Tests on these branches

are supposed to pass with the corresponding "default" and "stable" branch from

core Mercurial. The documentation is built from the tip of stable.

In addition, we have compatibility branches to check tests on older versions of

Mercurial. They are the "mercurial-x.y" branches. They are used to apply

expected test changes only, no code changes should happen there.

Test output changes from a changeset in core should add the following line to

their patch description:

CORE-TEST-OUTPUT-UPDATE: <CORE-NODE-ID>

Format-source config

====================

Format source helps smooth out the pain of merging after auto-formatting.

Follow the instructions for install here:

.. _`format-source`: https://bitbucket.org/octobus/format-source

Then update both your global and repo config files::

    $ hg config -l # add the lines below

    [extensions]

    formatsource =

    [format-source]

    byteify-strings = python3 ~/workspace/octobus/mercurial-devel/contrib/byteify-strings.py --dictiter --treat-as-kwargs kwargs opts commitopts TROUBLES --allow-attr-methods

    byteify-strings:mode.input = file

    byteify-strings:mode.output = pipe

Release Checklist

=================

* make sure the tests are happy on all supported versions,

  You can use the `contrib/merge-test-compat.sh` to merge with the test

  compatibility branches.

* make sure there is no code difference between the compat branches and stable

  (no diff within `hgext3rd/`),

* update the `testedwith` variable for all extensions (remove '.dev'):

  - hgext3rd/evolve/metadata.py

  - hgext3rd/topic/__init__.py

  - hgext3rd/pullbundle.py

* make sure the changelog is up to date,

* add a date to the changelog entry for the target version,

* update the `__version__` field of all relevant extensions:

  - hgext3rd/evolve/metadata.py

  - hgext3rd/topic/__init__.py

  - hgext3rd/pullbundle.py (if touched)

* create a new Debian entry:

  - debchange --newversion x.y.z-1 "new upstream release"

  - debchange --release

* sanity check install and sdist targets of setup.py:

  - python setup.py install --home=$(mktemp -d)

  - python setup.py sdist

* tag the commit,

* push and publish the tag,

* upload the tarball to PyPI,

* make an announcement on evolve-testers@mercurial-scm.org (possibly on

  mercurial@mercurial-scm.org too),

* bump versions of all extensions and add '.dev' (see existing commits as an

  example):

  - hgext3rd/evolve/metadata.py

  - hgext3rd/topic/__init__.py

  - hgext3rd/pullbundle.py

  The version we use on the stable branch during development should be

  `x.y.z+1.dev`. The version of the default branch should be `x.y+1.0.dev`.

* merge stable into default.