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  • Committer: Vincent Ladeuil
  • Date: 2016-02-01 19:26:41 UTC
  • mto: This revision was merged to the branch mainline in revision 6616.
  • Revision ID: v.ladeuil+lp@free.fr-20160201192641-mzn90m51rydhw00n
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doc/en/user-guide/hooks.txt
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perform actions before or after certain Bazaar operations.  The operations
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include ``commit``, ``push``, ``pull``, and ``uncommit``.
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For a complete list of hooks and their parameters, see `Hooks
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<../user-reference/bzr_man.html#hooks>`_ in the User Reference.
 
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<../user-reference/index.html#hooks>`_ in the User Reference.
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Most hooks are run on the client, but a few are run on the server.  (Also
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see the `bzr-push-and-update`_ plugin that handles one special case of
 
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see the `push-and-update plugin`_ that handles one special case of
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server-side operations.)
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.. _bzr-push-and-update: https://launchpad.net/bzr-push-and-update/
 
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.. _push-and-update plugin: http://doc.bazaar.canonical.com/plugins/en/push-and-update-plugin.html
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Using hooks
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-----------
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To use a hook, you should `write a plugin <#writing-a-plugin>`_.  Instead of
 
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To use a hook, you should `write a plugin`_.  Instead of
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creating a new command, this plugin will define and install the hook.  Here's
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an example::
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    branch.Branch.hooks.install_named_hook('post_push', post_push_hook,
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                                     'My post_push hook')
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.. _write a plugin: http://doc.bazaar.canonical.com/plugins/en/plugin-development.html
 
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To use this example, create a file named ``push_hook.py``, and stick it in
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``plugins`` subdirectory of your configuration directory.  (If you have never
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installed any plugins, you may need to create the ``plugins`` directory).
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itself.  The third argument is a name ``'My post_push hook'``, which can be
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used in progress messages and error messages.
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To reduce the start-up time of Bazaar it is also possible to "lazily" install hooks,
 
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using the ``bzrlib.hooks.install_lazy_named_hook`` function. This removes the need
 
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to load the module that contains the hook point just to install the hook. Here's lazy
 
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version of the example above::
 
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    from bzrlib import hooks
 
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    def post_push_hook(push_result):
 
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        print "The new revno is %d" % push_result.new_revno
 
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    hooks.install_lazy_named_hook('bzrlib.branch', 'Branch.hooks',
 
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        'post_push', post_push_hook, 'My post_push hook')
 
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Debugging hooks
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---------------
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To get a list of installed hooks, use the hidden ``hooks`` command::
 
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To get a list of installed hooks (and available hook points), use the hidden
 
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``hooks`` command::
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    bzr hooks
 
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Example: a merge plugin
 
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-----------------------
 
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Here's a complete plugin that demonstrates the ``Merger.merge_file_content``
 
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hook.  It installs a hook that forces any merge of a file named ``*.xml``
 
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to be a conflict, even if Bazaar thinks it can merge it cleanly.
 
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``merge_xml.py``::
 
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  """Custom 'merge' logic for *.xml files.
 
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  Always conflicts if both branches have changed the file.
 
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  """
 
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  from bzrlib.merge import PerFileMerger, Merger
 
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  def merge_xml_files_hook(merger):
 
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      """Hook to merge *.xml files"""
 
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      return AlwaysConflictXMLMerger(merger)
 
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  class AlwaysConflictXMLMerger(PerFileMerger):
 
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      def file_matches(self, params):
 
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          filename = self.get_filename(params, self.merger.this_tree)
 
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          return filename.endswith('.xml')
 
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      def merge_matching(self, params):
 
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          return 'conflicted', params.this_lines
 
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  Merger.hooks.install_named_hook(
 
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      'merge_file_content', merge_xml_files_hook, '*.xml file merge')
 
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``merge_file_content`` hooks are executed for each file to be merged.  For
 
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a more a complex example look at the ``news_merge`` plugin that's bundled with
 
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Bazaar in the ``bzrlib/plugins`` directory.
 
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