def __set_state(self, newvalue):
"""Set state to new value, ensuring it is a proper state and respects the state machine"""
if newvalue not in self._states:
raise DataStateError(newvalue)
if not hasattr(self, '_DataState__state'):
if newvalue != self._initial_state:
raise DataStateError(newvalue)
elif (self.__state, newvalue) not in self._transitions:
raise DataStateTransitionError((self.__state, newvalue))
self.__state = newvalue
def __init__(self, spec):
"""Validate states and transitions
Arguments:
spec -- a dictionary passed to the underlying Data class
Exceptions:
DataStateError -- _states, _transitions or _initial_state contains an improper value; accompanying message contains
additional information
"""
Data.__init__(self, spec)
if not isinstance(self._states, list):
raise DataStateError("_states attribute is not a list: %s" % (self._states,))
if self._initial_state == None:
raise DataStateError("_initial_state is not set")
if self._initial_state not in self._states:
raise DataStateError("_initial_state is not a valid state: %s" % (self._initial_state,))
if not isinstance(self._transitions, list):
raise DataStateError("_transitions attribute is not a list: %s" % (self._transitions,))
for transition in self._transitions:
if not isinstance(transition, tuple) or len(transition) != 2:
raise DataStateError("_transition is not a 2-tuple: %s" % (transition,))
old_state, new_state = transition
if old_state not in self._states:
raise DataStateError("_transition contains a invalid state: %s" % (old_state,))
if new_state not in self._states:
raise DataStateError("_transition contains a invalid state: %s" % (new_state,))