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# Copyright (C) 2006 Canonical Ltd
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# Copyright (C) 2006, 2008 Canonical Ltd
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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"""Classes to provide name-to-object registry-like support."""
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return super(_LazyObjectGetter, self).get_obj()
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def _do_import(self):
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obj = __import__(self._module_name, globals(), locals(),
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obj = getattr(obj, self._member_name)
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segments = self._member_name.split('.')
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names = [self._member_name]
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obj = __import__(self._module_name, globals(), locals(), names)
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for segment in segments:
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obj = getattr(obj, segment)
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self._imported = True
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:param obj: The object to register.
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:param help: Help text for this entry. This may be a string or
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a callable. If it is a callable, it should take two
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parameters (registry, key): this registry and the key that
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parameters (registry, key): this registry and the key that
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the help was registered under.
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:param info: More information for this entry. Registry.get_info()
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can be used to get this information. Registry treats this as an
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"""Register a new object to be loaded on request.
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:param module_name: The python path to the module. Such as 'os.path'.
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:param member_name: The member of the module to return. If empty or
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:param member_name: The member of the module to return. If empty or
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None, get() will return the module itself.
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:param help: Help text for this entry. This may be a string or
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:param info: More information for this entry. Registry
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:param info: More information for this entry. Registry
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:param override_existing: If True, replace the existing object
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with the new one. If False, if there is already something
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registered with the same key, raise a KeyError
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"""Return the object register()'ed to the given key.
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May raise ImportError if the object was registered lazily and
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there are any problems, or AttributeError if the module does not
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there are any problems, or AttributeError if the module does not
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have the supplied member.
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:param key: The key to obtain the object for. If no object has been
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return self._dict[self._get_key_or_default(key)].get_obj()
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def get_prefix(self, fullname):
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"""Return an object whose key is a prefix of the supplied value.
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:fullname: The name to find a prefix for
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:return: a tuple of (object, remainder), where the remainder is the
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portion of the name that did not match the key.
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for key in self.keys():
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if fullname.startswith(key):
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return self.get(key), fullname[len(key):]
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def _get_key_or_default(self, key=None):
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"""Return either 'key' or the default key if key is None"""
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if key is not None:
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for key, getter in self._dict.iteritems():
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yield key, getter.get_obj()
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# We should not use the iteritems() implementation below (see bug
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return sorted([(key, getter.get_obj())
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for key, getter in self._dict.items()])
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def _set_default_key(self, key):
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if not self._dict.has_key(key):
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raise KeyError('No object registered under key %s.' % key)
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default_key = property(_get_default_key, _set_default_key,
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doc="Current value of the default key."
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" Can be set to any existing key.")
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class FormatRegistry(Registry):
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"""Registry specialised for handling formats."""
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def __init__(self, other_registry=None):
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Registry.__init__(self)
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self._other_registry = other_registry
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def register_lazy(self, key, module_name, member_name,
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help=None, info=None,
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override_existing=False):
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# Overridden to allow capturing registrations to two seperate
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# registries in a single call.
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Registry.register_lazy(self, key, module_name, member_name,
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help=help, info=info, override_existing=override_existing)
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if self._other_registry is not None:
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self._other_registry.register_lazy(key, module_name, member_name,
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help=help, info=info, override_existing=override_existing)
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def get(self, format_string):
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r = Registry.get(self, format_string)