Source code for timelinelib.general.observer
# Copyright (C) 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018 Rickard Lindberg, Roger Lindberg
#
# This file is part of Timeline.
#
# Timeline is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Timeline is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Timeline. If not, see <http://www.gnu.org/licenses/>.
[docs]class Observable:
[docs] def __init__(self):
self._observers = []
self._listeners = []
[docs] def listen_for(self, event, function):
self._listeners.append((True, event, function))
[docs] def listen_for_any(self, function):
self._listeners.append((False, None, function))
[docs] def unlisten(self, function):
self._listeners = [x for x in self._listeners if x[2] != function]
[docs] def register(self, fn):
self._observers.append(fn)
[docs] def unregister(self, fn):
if fn in self._observers:
self._observers.remove(fn)
def _notify(self, state_change=None):
for (listen_for_specific, event, function) in self._listeners:
if listen_for_specific:
if state_change == event:
function()
else:
function()
for fn in self._observers:
fn(state_change)
[docs]class Listener:
[docs] def __init__(self, callback):
self._observable = None
self._callback = callback
[docs] def set_observable(self, observable):
self._unlisten()
self._observable = observable
self._listen()
def _unlisten(self):
if self._observable is not None:
self._observable.unlisten(self._listener)
def _listen(self):
if self._observable is not None:
self._observable.listen_for_any(self._listener)
self._listener()
def _listener(self):
self._callback(self._observable)