Echo is a small library for attaching callback functions to property state changes. For example:
class Switch(object):
state = CallbackProperty('off')
def report_change(state):
print 'the switch is %s' % state
s = Switch()
add_callback(s, 'state', report_change)
s.state = 'on' # prints 'the switch is on'
CalllbackProperties can also be built using decorators
class Switch(object):
@callback_property
def state(self):
return self._state
@state.setter
def state(self, value):
if value not in ['on', 'off']:
raise ValueError("invalid setting")
self._state = value
Full documentation is avilable here