comparison docs/index.rst @ 2872:78debdfb3e4d

doc: simplify the reference to in-core features

This should do the whole thing lighter.

2871:c6289ec369cb

With core Mercurial, changesets are permanent and immutable. You can
commit new changesets to modify your source code, but you cannot
modify or remove old changesets.

For years, Mercurial has included various extensions that allow
history modification: ``rebase``, ``mq``, ``histedit``, and so forth.
These are useful and popular extensions, and in fact history
modification is one of the big reasons DVCSes (distributed version
control systems) like Mercurial took off.

But there's a catch: until now, Mercurial's various mechanisms for
modifying history have been *unsafe*, in that changesets were
destroyed (“stripped”) rather than simply made hidden.

``evolve`` makes things better in a couple of ways:

  * It changes the behaviour of most existing history modification
    extensions (``rebase``, ``histedit``, etc.) so they use a safer
    mechanism (*changeset obsolescence*, covered below) rather than
    the older, less safe *strip* operation.

  * It provides a new way of modifying history that is roughly
    equivalent to ``mq`` (but much nicer and safer).

It helps to understand that ``evolve`` builds on infrastructure
already in core Mercurial:

  * *Phases* (starting in Mercurial 2.1) allow you to distinguish
    mutable and immutable changesets. We'll cover phases early in the
    user guide, since understanding phases is essential to
    understanding ``evolve``.

  * *Changeset obsolescence* (starting in Mercurial 2.3) is how
    Mercurial knows how history has been modified, specifically when
    one changeset replaces another. In the obsolescence model, a
    changeset is neither removed nor modified, but is instead marked
    *obsolete* and typically replaced by a *successor*. Obsolete
    changesets usually become *hidden* as well. Obsolescence is an
    invisible feature until you start using ``evolve``, so we'll cover
    it in the user guide too.

Some of the things you can do with ``evolve`` are:

  * Fix a mistake immediately: “Oops! I just committed a changeset
    with a syntax error—I'll fix that and amend the changeset so no

2872:78debdfb3e4d

With core Mercurial, changesets are permanent and immutable. You can
commit new changesets to modify your source code, but you cannot
modify or remove old changesets.

For years, Mercurial has included various commands that allow
history modification: ``rebase``, ``histedit``, ``commit --amend`` and so forth.
But there's a catch: until now, Mercurial's various mechanisms for
modifying history have been *unsafe*, in that changesets were
destroyed (“stripped”) rather than simply made hidden.

``evolve`` makes things better by changing the behaviour of most existing
history modification commands so they use a safer mechanism (*changeset
obsolescence*, covered below) rather than the older, less safe *strip*
operation.

``evolve`` is built on infrastructure in core Mercurial:

  * *Phases* (starting in Mercurial 2.1) allow you to distinguish
    mutable and immutable changesets.

  * *Changeset obsolescence* (starting in Mercurial 2.3) is how
    Mercurial knows how history has been modified, specifically when
    one changeset replaces another. In the obsolescence model, a
    changeset is neither removed nor modified, but is instead marked
    *obsolete* and typically replaced by a *successor*. Obsolete
    changesets usually become *hidden* as well. Obsolescence is an
    invisible feature in Mercurial until you start using ``evolve``.

Some of the things you can do with ``evolve`` are:

  * Fix a mistake immediately: “Oops! I just committed a changeset
    with a syntax error—I'll fix that and amend the changeset so no