Using hooks

One way to customize Bazaar's behaviour is with hooks. Hooks allow you to perform actions before or after certain Bazaar operations. The operations include commit, push, pull, and uncommit.

Using Hooks

To use a hook, you should write a plugin. Instead of creating a new command, this plugin will define and install the hook. Here's an example:

from bzrlib import branch


def post_push_hook(push_result):
    print "The new revno is %d" % push_result.new_revno


branch.Branch.hooks.install_hook('post_push', post_push_hook)
branch.Branch.hooks.name_hook(post_push_hook, 'My post_push hook')

To use this example, create a file named push_hook.py, and stick it in plugins subdirectory of your configuration directory. (If you have never installed any plugins, you may need to create the plugins directory).

First, we define a function that will be run after push completes. We could also use an instance method or a callable object. All push hooks take a single argument, the push_result.

Next, we install the hook. 'post_push' identifies where we want to install the hook, and the second parameter is the hook itself.

Finally, we name the hook. This is optional, but it means the hook name can be used in progress messages and error messages.

That's it! The next time you push, it should show "The new revno is...". Of course, hooks can be much more elaborate than this, because you have the full power of Python at your disposal. Now that you know how to use hooks, what you do with them is up to you.

For a complete list of hooks and their parameters, see the Hooks Reference.