~bzr-pqm/bzr/bzr.dev

Reusing a checkout

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

Motivation

----------

At times, it can be useful to have a single checkout as your

sandbox for working on multiple branches. Some possible reasons

for this include:

 * saving disk space when the working tree is large

 * developing in a fixed location.

In many cases, working tree disk usage swamps the size of the

``.bzr`` directory. If you want to work on multiple branches

but can't afford the overhead of a full working tree for each,

reusing a checkout across multiples branches is the way to go.

On other occasions, the location of your sandbox might be

configured into numerous development and testing tools. Once

again, reusing a checkout across multiple branches can help.

Changing where a branch is bound to

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

To change where a checkout is bound to, follow these steps:

 1. Make sure that any local changes have been committed

    centrally so that no work is lost.

 2. Use the ``bind`` command giving the URL of the new

    remote branch you wish to work on.

 3. Make your checkout a copy of the desired branch by using

    the ``update`` command followed by the ``revert`` command.

Note that simply binding to a new branch and running ``update``

merges in your local changes, both committed and uncommitted. You need

to decide whether to keep them or not by running either ``revert``

or ``commit``.

An alternative to the bind+update recipe is using the ``switch``

command. This is basically the same as removing the existing

branch and running ``checkout`` again on the new location, except

that any uncommitted changes in your tree are merged in.

Note: As ``switch`` can potentially throw away committed changes in

order to make a checkout an accurate cache of a different bound branch,

it will fail by design if there are changes which have been committed

locally but are not yet committed to the most recently bound branch.

To truly abandon these changes, use the ``--force`` option.

Switching a lightweight checkout

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

With a lightweight checkout, there are no local commits and ``switch``

effectively changes which branch the working tree is associated with.

One possible setup is to use a lightweight checkout in combination

with a local tree-less repository. This lets you switch what you

are working on with ease. For example::

  bzr init-repo --no-trees PROJECT

  cd PROJECT

  bzr branch sftp://centralhost/srv/bzr/PROJECT/trunk

  bzr checkout --lightweight trunk my-sandbox

  cd my-sandbox

  (hack away)

Note that trunk in this example will have a ``.bzr`` directory within it

but there will be no working tree there as the branch was created in

a tree-less repository. You can grab or create as many branches as you

need there and switch between them as required. For example::

  (assuming in my-sandbox)

  bzr branch sftp://centralhost/srv/bzr/PROJECT/PROJECT-1.0 ../PROJECT-1.0

  bzr switch ../PROJECT-1.0

  (fix bug in 1.0)

  bzr commit -m "blah, blah blah"

  bzr switch ../trunk

  (go back to working on the trunk)

Note: The branches may be local only or they may be bound to

remote ones (by creating them with ``checkout`` or by using ``bind``

after creating them with ``branch``).