openstack
/
automaton
Code Issues Proposed changes

Add pre and post event processing methods

This commit is contained in:
Joshua Harlow 2014-12-07 19:08:43 -08:00
parent 4de39147cd
commit 8c897cfa6f
1 changed files with 11 additions and 3 deletions
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14
automaton/machines.py
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@ -183,8 +183,7 @@ class FiniteMachine(object):
self._states[end]['on_enter'],
self._states[start]['on_exit'])
def process_event(self, event):
"""Trigger a state change in response to the provided event."""
def _pre_process_event(self, event):
current = self._current
if current is None:
raise excp.NotInitialized("Can only process events after"
@ -197,13 +196,22 @@ class FiniteMachine(object):
raise excp.NotFound("Can not transition from state '%s' on"
" event '%s' (no defined transition)"
% (current.name, event))
def _post_process_event(self, event, result):
return result
def process_event(self, event):
"""Trigger a state change in response to the provided event."""
self._pre_process_event(event)
current = self._current
replacement = self._transitions[current.name][event]
if current.on_exit is not None:
current.on_exit(current.name, event)
if replacement.on_enter is not None:
replacement.on_enter(replacement.name, event)
self._current = replacement
return self._effect_builder(self._states[replacement.name], event)
result = self._effect_builder(self._states[replacement.name], event)
return self._post_process_event(event, result)
def initialize(self):
"""Sets up the state machine (sets current state to start state...)."""