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251
sqlalchemy/orm/identity.py
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251
sqlalchemy/orm/identity.py
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# identity.py
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# Copyright (C) the SQLAlchemy authors and contributors
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#
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# This module is part of SQLAlchemy and is released under
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# the MIT License: http://www.opensource.org/licenses/mit-license.php
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import weakref
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from sqlalchemy import util as base_util
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from sqlalchemy.orm import attributes
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class IdentityMap(dict):
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def __init__(self):
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self._mutable_attrs = set()
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self._modified = set()
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self._wr = weakref.ref(self)
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def replace(self, state):
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raise NotImplementedError()
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def add(self, state):
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raise NotImplementedError()
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def remove(self, state):
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raise NotImplementedError()
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def update(self, dict):
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raise NotImplementedError("IdentityMap uses add() to insert data")
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def clear(self):
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raise NotImplementedError("IdentityMap uses remove() to remove data")
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def _manage_incoming_state(self, state):
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state._instance_dict = self._wr
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if state.modified:
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self._modified.add(state)
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if state.manager.mutable_attributes:
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self._mutable_attrs.add(state)
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def _manage_removed_state(self, state):
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del state._instance_dict
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self._mutable_attrs.discard(state)
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self._modified.discard(state)
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def _dirty_states(self):
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return self._modified.union(s for s in self._mutable_attrs.copy()
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if s.modified)
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def check_modified(self):
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"""return True if any InstanceStates present have been marked as 'modified'."""
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if self._modified:
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return True
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else:
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for state in self._mutable_attrs.copy():
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if state.modified:
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return True
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return False
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def has_key(self, key):
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return key in self
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def popitem(self):
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raise NotImplementedError("IdentityMap uses remove() to remove data")
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def pop(self, key, *args):
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raise NotImplementedError("IdentityMap uses remove() to remove data")
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def setdefault(self, key, default=None):
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raise NotImplementedError("IdentityMap uses add() to insert data")
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def copy(self):
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raise NotImplementedError()
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def __setitem__(self, key, value):
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raise NotImplementedError("IdentityMap uses add() to insert data")
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def __delitem__(self, key):
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raise NotImplementedError("IdentityMap uses remove() to remove data")
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class WeakInstanceDict(IdentityMap):
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def __getitem__(self, key):
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state = dict.__getitem__(self, key)
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o = state.obj()
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if o is None:
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o = state._is_really_none()
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if o is None:
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raise KeyError, key
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return o
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def __contains__(self, key):
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try:
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if dict.__contains__(self, key):
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state = dict.__getitem__(self, key)
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o = state.obj()
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if o is None:
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o = state._is_really_none()
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else:
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return False
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except KeyError:
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return False
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else:
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return o is not None
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def contains_state(self, state):
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return dict.get(self, state.key) is state
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def replace(self, state):
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if dict.__contains__(self, state.key):
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existing = dict.__getitem__(self, state.key)
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if existing is not state:
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self._manage_removed_state(existing)
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else:
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return
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dict.__setitem__(self, state.key, state)
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self._manage_incoming_state(state)
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def add(self, state):
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if state.key in self:
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if dict.__getitem__(self, state.key) is not state:
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raise AssertionError("A conflicting state is already "
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"present in the identity map for key %r"
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% (state.key, ))
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else:
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dict.__setitem__(self, state.key, state)
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self._manage_incoming_state(state)
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def remove_key(self, key):
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state = dict.__getitem__(self, key)
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self.remove(state)
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def remove(self, state):
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if dict.pop(self, state.key) is not state:
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raise AssertionError("State %s is not present in this identity map" % state)
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self._manage_removed_state(state)
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def discard(self, state):
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if self.contains_state(state):
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dict.__delitem__(self, state.key)
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self._manage_removed_state(state)
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def get(self, key, default=None):
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state = dict.get(self, key, default)
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if state is default:
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return default
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o = state.obj()
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if o is None:
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o = state._is_really_none()
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if o is None:
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return default
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return o
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# Py2K
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def items(self):
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return list(self.iteritems())
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def iteritems(self):
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for state in dict.itervalues(self):
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# end Py2K
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# Py3K
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#def items(self):
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# for state in dict.values(self):
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value = state.obj()
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if value is not None:
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yield state.key, value
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# Py2K
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def values(self):
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return list(self.itervalues())
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def itervalues(self):
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for state in dict.itervalues(self):
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# end Py2K
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# Py3K
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#def values(self):
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# for state in dict.values(self):
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instance = state.obj()
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if instance is not None:
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yield instance
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def all_states(self):
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# Py3K
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# return list(dict.values(self))
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# Py2K
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return dict.values(self)
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# end Py2K
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def prune(self):
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return 0
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class StrongInstanceDict(IdentityMap):
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def all_states(self):
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return [attributes.instance_state(o) for o in self.itervalues()]
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def contains_state(self, state):
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return state.key in self and attributes.instance_state(self[state.key]) is state
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def replace(self, state):
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if dict.__contains__(self, state.key):
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existing = dict.__getitem__(self, state.key)
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existing = attributes.instance_state(existing)
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if existing is not state:
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self._manage_removed_state(existing)
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else:
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return
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dict.__setitem__(self, state.key, state.obj())
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self._manage_incoming_state(state)
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def add(self, state):
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if state.key in self:
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if attributes.instance_state(dict.__getitem__(self, state.key)) is not state:
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raise AssertionError("A conflicting state is already present in the identity map for key %r" % (state.key, ))
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else:
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dict.__setitem__(self, state.key, state.obj())
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self._manage_incoming_state(state)
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def remove(self, state):
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if attributes.instance_state(dict.pop(self, state.key)) is not state:
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raise AssertionError("State %s is not present in this identity map" % state)
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self._manage_removed_state(state)
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def discard(self, state):
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if self.contains_state(state):
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dict.__delitem__(self, state.key)
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self._manage_removed_state(state)
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def remove_key(self, key):
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state = attributes.instance_state(dict.__getitem__(self, key))
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self.remove(state)
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def prune(self):
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"""prune unreferenced, non-dirty states."""
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ref_count = len(self)
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dirty = [s.obj() for s in self.all_states() if s.modified]
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# work around http://bugs.python.org/issue6149
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keepers = weakref.WeakValueDictionary()
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keepers.update(self)
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dict.clear(self)
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dict.update(self, keepers)
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self.modified = bool(dirty)
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return ref_count - len(self)
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