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from __future__ import absolute_import
class StateObject(object):
"""
An object with serializable state.
State attributes can either be serializable types(str, tuple, bool, ...)
or StateObject instances themselves.
"""
# An attribute-name -> class-or-type dict containing all attributes that
# should be serialized. If the attribute is a class, it must implement the
# StateObject protocol.
_stateobject_attributes = None
# A set() of attributes that should be ignored for short state
_stateobject_long_attributes = frozenset([])
def from_state(self, state):
raise NotImplementedError()
def get_state(self, short=False):
"""
Retrieve object state. If short is true, return an abbreviated
format with long data elided.
"""
state = {}
for attr, cls in self._stateobject_attributes.iteritems():
if short and attr in self._stateobject_long_attributes:
continue
val = getattr(self, attr)
if hasattr(val, "get_state"):
state[attr] = val.get_state(short)
else:
state[attr] = val
return state
def load_state(self, state):
"""
Load object state from data returned by a get_state call.
"""
for attr, cls in self._stateobject_attributes.iteritems():
if state.get(attr, None) is None:
setattr(self, attr, None)
else:
curr = getattr(self, attr)
if hasattr(curr, "load_state"):
curr.load_state(state[attr])
elif hasattr(cls, "from_state"):
setattr(self, attr, cls.from_state(state[attr]))
else:
setattr(self, attr, cls(state[attr]))
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