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).

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