diff options
Diffstat (limited to 'sleekxmpp/xmlstream/statemachine.py')
| -rw-r--r-- | sleekxmpp/xmlstream/statemachine.py | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/sleekxmpp/xmlstream/statemachine.py b/sleekxmpp/xmlstream/statemachine.py index 704cabdb..c6e0ea41 100644 --- a/sleekxmpp/xmlstream/statemachine.py +++ b/sleekxmpp/xmlstream/statemachine.py @@ -105,6 +105,32 @@ class StateMachine(object): def transition_ctx(self, from_state, to_state, wait=0.0): + ''' + Use the state machine as a context manager. The transition occurs on /exit/ from + the `with` context, so long as no exception is thrown. For example: + + :: + + with state_machine.transition_ctx('one','two', wait=5) as locked: + if locked: + # the state machine is currently locked in state 'one', and will + # transition to 'two' when the 'with' statement ends, so long as + # no exception is thrown. + print 'Currently locked in state one: %s' % state_machine['one'] + + else: + # The 'wait' timed out, and no lock has been acquired + print 'Timed out before entering state "one"' + + print 'Since no exception was thrown, we are now in state "two": %s' % state_machine['two'] + + + The other main difference between this method and `transition()` is that the + state machine is locked for the duration of the `with` statement (normally, + after a `transition() occurs, the state machine is immediately unlocked and + available to another thread to call `transition()` again. + ''' + if not from_state in self.__states: raise ValueError( "StateMachine does not contain from_state %s." % state ) if not to_state in self.__states: |