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Viewing changes to bzrlib/hooks.py

Add bzrlib.pyutils, which has get_named_object, a wrapper around __import__.

This is used to replace various ad hoc implementations of the same logic,
notably the version used in registry's _LazyObjectGetter which had a bug when
getting a module without also getting a member.  And of course, this new
function has unit tests, unlike the replaced code.

This also adds a KnownHooksRegistry subclass to provide a more natural home for
some other logic.

I'm not thrilled about the name of the new module or the new functions, but it's
hard to think of good names for such generic functionality.

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Lines of Context:
bzrlib/hooks.py
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"""Support for plugin hooking logic."""
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from bzrlib import registry
 
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from bzrlib import (
 
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    pyutils,
 
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    registry,
 
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    symbol_versioning,
 
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    )
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from bzrlib.lazy_import import lazy_import
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lazy_import(globals(), """
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import textwrap
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""")
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known_hooks = registry.Registry()
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# known_hooks registry contains
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# tuple of (module, member name) which is the hook point
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# module where the specific hooks are defined
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# callable to get the empty specific Hooks for that attribute
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known_hooks.register_lazy(('bzrlib.branch', 'Branch.hooks'), 'bzrlib.branch',
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    'BranchHooks')
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known_hooks.register_lazy(('bzrlib.bzrdir', 'BzrDir.hooks'), 'bzrlib.bzrdir',
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    'BzrDirHooks')
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known_hooks.register_lazy(('bzrlib.commands', 'Command.hooks'),
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    'bzrlib.commands', 'CommandHooks')
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known_hooks.register_lazy(('bzrlib.info', 'hooks'),
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    'bzrlib.info', 'InfoHooks')
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known_hooks.register_lazy(('bzrlib.lock', 'Lock.hooks'), 'bzrlib.lock',
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    'LockHooks')
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known_hooks.register_lazy(('bzrlib.merge', 'Merger.hooks'), 'bzrlib.merge',
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    'MergeHooks')
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known_hooks.register_lazy(('bzrlib.msgeditor', 'hooks'), 'bzrlib.msgeditor',
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    'MessageEditorHooks')
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known_hooks.register_lazy(('bzrlib.mutabletree', 'MutableTree.hooks'),
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    'bzrlib.mutabletree', 'MutableTreeHooks')
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known_hooks.register_lazy(('bzrlib.smart.client', '_SmartClient.hooks'),
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    'bzrlib.smart.client', 'SmartClientHooks')
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known_hooks.register_lazy(('bzrlib.smart.server', 'SmartTCPServer.hooks'),
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    'bzrlib.smart.server', 'SmartServerHooks')
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known_hooks.register_lazy(('bzrlib.status', 'hooks'),
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    'bzrlib.status', 'StatusHooks')
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known_hooks.register_lazy(
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    ('bzrlib.version_info_formats.format_rio', 'RioVersionInfoBuilder.hooks'),
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    'bzrlib.version_info_formats.format_rio', 'RioVersionInfoBuilderHooks')
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known_hooks.register_lazy(
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    ('bzrlib.merge_directive', 'BaseMergeDirective.hooks'),
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    'bzrlib.merge_directive', 'MergeDirectiveHooks')
 
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class KnownHooksRegistry(registry.Registry):
 
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    # known_hooks registry contains
 
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    # tuple of (module, member name) which is the hook point
 
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    # module where the specific hooks are defined
 
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    # callable to get the empty specific Hooks for that attribute
 
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    def register_lazy_hook(self, hook_module_name, hook_member_name,
 
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            hook_factory_member_name):
 
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        self.register_lazy((hook_module_name, hook_member_name),
 
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            hook_module_name, hook_factory_member_name)
 
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    def iter_parent_objects(self):
 
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        """Yield (hook_key, (parent_object, attr)) tuples for every registered
 
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        hook, where 'parent_object' is the object that holds the hook
 
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        instance.
 
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        This is useful for resetting/restoring all the hooks to a known state,
 
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        as is done in bzrlib.tests.TestCase._clear_hooks.
 
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        """
 
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        for key in self.keys():
 
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            yield key, self.key_to_parent_and_attribute(key)
 
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    def key_to_parent_and_attribute(self, (module_name, member_name)):
 
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        """Convert a known_hooks key to a (parent_obj, attr) pair.
 
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        :param key: A tuple (module_name, member_name) as found in the keys of
 
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            the known_hooks registry.
 
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        :return: The parent_object of the hook and the name of the attribute on
 
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            that parent object where the hook is kept.
 
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        """
 
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        parent_mod, parent_member, attr = pyutils.calc_parent_name(module_name,
 
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            member_name)
 
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        return pyutils.get_named_object(parent_mod, parent_member), attr
 
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known_hooks = KnownHooksRegistry()
 
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known_hooks.register_lazy_hook('bzrlib.branch', 'Branch.hooks', 'BranchHooks')
 
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known_hooks.register_lazy_hook('bzrlib.bzrdir', 'BzrDir.hooks', 'BzrDirHooks')
 
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known_hooks.register_lazy_hook(
 
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    'bzrlib.commands', 'Command.hooks', 'CommandHooks')
 
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known_hooks.register_lazy_hook('bzrlib.info', 'hooks', 'InfoHooks')
 
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known_hooks.register_lazy_hook('bzrlib.lock', 'Lock.hooks', 'LockHooks')
 
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known_hooks.register_lazy_hook('bzrlib.merge', 'Merger.hooks', 'MergeHooks')
 
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known_hooks.register_lazy_hook(
 
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    'bzrlib.msgeditor', 'hooks', 'MessageEditorHooks')
 
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known_hooks.register_lazy_hook(
 
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    'bzrlib.mutabletree', 'MutableTree.hooks', 'MutableTreeHooks')
 
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known_hooks.register_lazy_hook(
 
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    'bzrlib.smart.client', '_SmartClient.hooks', 'SmartClientHooks')
 
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known_hooks.register_lazy_hook(
 
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    'bzrlib.smart.server', 'SmartTCPServer.hooks', 'SmartServerHooks')
 
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known_hooks.register_lazy_hook(
 
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    'bzrlib.status', 'hooks', 'StatusHooks')
 
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known_hooks.register_lazy_hook(
 
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    'bzrlib.version_info_formats.format_rio', 'RioVersionInfoBuilder.hooks',
 
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    'RioVersionInfoBuilderHooks')
 
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known_hooks.register_lazy_hook(
 
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    'bzrlib.merge_directive', 'BaseMergeDirective.hooks', 'MergeDirectiveHooks')
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def known_hooks_key_to_object((module_name, member_name)):
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        the known_hooks registry.
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    :return: The object this specifies.
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    """
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    return registry._LazyObjectGetter(module_name, member_name).get_obj()
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def known_hooks_key_to_parent_and_attribute((module_name, member_name)):
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    """Convert a known_hooks key to a object.
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    :param key: A tuple (module_name, member_name) as found in the keys of
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        the known_hooks registry.
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    :return: The object this specifies.
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    """
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    member_list = member_name.rsplit('.', 1)
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    if len(member_list) == 2:
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        parent_name, attribute = member_list
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    else:
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        parent_name = None
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        attribute = member_name
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    parent = known_hooks_key_to_object((module_name, parent_name))
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    return parent, attribute
 
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    return pyutils.get_named_object(module_name, member_name)
 
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@symbol_versioning.deprecated_function(symbol_versioning.deprecated_in((2, 3)))
 
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def known_hooks_key_to_parent_and_attribute(key):
 
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    """See KnownHooksRegistry.key_to_parent_and_attribute."""
 
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    return known_hooks.key_to_parent_and_attribute(key)
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class Hooks(dict):