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eventdispatcher.py
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eventdispatcher.py
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# EventDispatcher - An event dispatcher for Python.
# Copyright (C) 2015 Dario Giovannetti <dev@dariogiovannetti.net>
#
# This file is part of EventDispatcher.
#
# EventDispatcher 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.
#
# EventDispatcher 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 EventDispatcher. If not, see <http://www.gnu.org/licenses/>.
class EventDispatcher:
# TODO: Use weakref when binding handlers
def __init__(self):
self.handlers = {}
def bind(self, event, handler):
"""
Bind a handler to an event.
"""
try:
self.handlers[event].add(handler)
except KeyError:
self.handlers[event] = set((handler, ))
def bind_one(self, event, handler):
"""
Bind a handler to an event and unbind all the others.
"""
self.handlers[event] = set((handler, ))
def unbind(self, event, handler):
"""
Unbind a handler from an event.
"""
self.handlers[event].discard(handler)
def unbind_all(self, event):
"""
Unbind all handlers from an event.
"""
del self.handlers[event]
def has_handlers(self, event):
"""
Return True if event has at least one handler, False otherwise.
"""
try:
return len(self.handlers[event]) > 0
except KeyError:
return False
def fire(self, event, *args, **kwargs):
"""
Fire an event.
"""
try:
handlerbag = self.handlers[event]
except KeyError:
pass
else:
# TODO: Test what happens if the handler has been
# deleted/garbage-collected, and possibly protect from the
# resulting exception
for handler in handlerbag:
handler(*args, **kwargs)