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added function execution on transition, and more unit tests.

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This commit is contained in:
Thom Nichols 2010-06-03 14:12:06 -04:00
parent d20cd6b3e6
commit f54501a346
1 changed files with 25 additions and 5 deletions
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30
sleekxmpp/xmlstream/statemachine.py
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@ -10,6 +10,7 @@ import threading
import time
import logging
class StateMachine(object):
def __init__(self, states=[]):
@ -27,7 +28,7 @@ class StateMachine(object):
self.__states.append( state )
def transition(self, from_state, to_state, wait=0.0):
def transition(self, from_state, to_state, wait=0.0, func=None, args=[], kwargs={} ):
'''
Transition from the given `from_state` to the given `to_state`.
This method will return `True` if the state machine is now in `to_state`. It
@ -47,12 +48,22 @@ class StateMachine(object):
if thread_should_exit: return
# perform actions here after successful transition
This allows the thread to be interrupted by setting `thread_should_exit=True`
This allows the thread to be responsive by setting `thread_should_exit=True`.
The optional `func` argument allows the user to pass a callable operation which occurs
within the context of the state transition (e.g. while the state machine is locked.)
If `func` returns a True value, the transition will occur. If `func` returns a non-
True value or if an exception is thrown, the transition will not occur. Any thrown
exception is not caught by the state machine and is the caller's responsibility to handle.
If `func` completes normally, this method will return the value returned by `func.` If
values for `args` and `kwargs` are provided, they are expanded and passed like so:
`func( *args, **kwargs )`.
'''
return self.transition_any( (from_state,), to_state, wait=wait )
return self.transition_any( (from_state,), to_state, wait=wait,
func=func, args=args, kwargs=kwargs )
def transition_any(self, from_states, to_state, wait=0.0):
def transition_any(self, from_states, to_state, wait=0.0, func=None, args=[], kwargs={} ):
'''
Transition from any of the given `from_states` to the given `to_state`.
'''
@ -73,10 +84,19 @@ class StateMachine(object):
self.lock.wait(wait)
if self.__current_state in from_states: # should always be True due to lock
return_val = True
# Note that func might throw an exception, but that's OK, it aborts the transition
if func is not None: return_val = func(*args,**kwargs)
# some 'false' value returned from func,
# indicating that transition should not occur:
if not return_val: return return_val
logging.debug(' ==== TRANSITION %s -> %s', self.__current_state, to_state)
self.__current_state = to_state
self.lock.notifyAll()
return True
return return_val # some 'true' value returned by func or True if func was None
else:
logging.error( "StateMachine bug!! The lock should ensure this doesn't happen!" )
return False