"""
File: signal.py
Author: Thiago Marcos P. Santos
Created: August 28, 2008
Purpose: A signal/slot implementation
"""
from weakref import WeakValueDictionary
class Signal(object):
def __init__(self):
self.__slots = WeakValueDictionary()
def __call__(self, *args, **kargs):
for key in self.__slots:
func, _ = key
func(self.__slots[key], *args, **kargs)
def connect(self, slot):
key = (slot.im_func, id(slot.im_self))
self.__slots[key] = slot.im_self
def disconnect(self, slot):
key = (slot.im_func, id(slot.im_self))
if key in self.__slots:
self.__slots.pop(key)
def clear(self):
self.__slots.clear()
# Sample usage:
class Model(object):
def __init__(self, value):
self.__value = value
self.changed = Signal()
def set_value(self, value):
self.__value = value
self.changed() # Emit signal
def get_value(self):
return self.__value
class View(object):
def __init__(self, model):
self.model = model
model.changed.connect(self.model_changed)
def model_changed(self):
print "New value:", self.model.get_value()
model = Model(10)
view1 = View(model)
view2 = View(model)
view3 = View(model)
model.set_value(20)
del view1
model.set_value(30)
model.changed.clear()
model.set_value(40)
