Source Code for Module rats.sig

 1  #!/usr/bin/env python 
 2  """ 
 3  File:    signal.py 
 4  Author:  Thiago Marcos P. Santos 
 5  Created: August 28, 2008 
 6   
 7  Purpose: A signal/slot implementation 
 8  Source: http://code.activestate.com/recipes/576477/ 
 9   
10  A Signal calls all the callbacks registered in its slots whenever it state  
11  changes.  
12  """ 
13   
14  from weakref import WeakValueDictionary 
15   
16 -class Signal(object): 
17      """ 
18      A Signal is callable. When called, it calls all the callables in its slots. 
19      """ 
20 -    def __init__(self): 
21          self._slots = WeakValueDictionary() 
22   
23 -    def __call__(self, *args, **kargs): 
24          for key in self._slots: 
25              func, _ = key 
26              func(self._slots[key], *args, **kargs) 
27   
28 -    def connect(self, slot): 
29          """ 
30          Slots must call this to register a callback method. 
31          :param slot: callable 
32          """ 
33          key = (slot.im_func, id(slot.im_self)) 
34          self._slots[key] = slot.im_self 
35   
36 -    def disconnect(self, slot): 
37          """ 
38          They can also unregister their callbacks here. 
39          :param slot: callable 
40          """ 
41          key = (slot.im_func, id(slot.im_self)) 
42          if key in self._slots: 
43              self._slots.pop(key) 
44   
45 -    def clear(self): 
46          """ 
47          Clears all slots 
48          """ 
49          self._slots.clear() 
50   
51  if __name__ == "__main__": 
52      # Sample usage: 
53 -    class Model(object): 
54 -        def __init__(self, value): 
55              self._value = value 
56              self.changed = Signal() 
57   
58 -        def set_value(self, value): 
59              self._value = value 
60              self.changed() # Emit signal 
61   
62 -        def get_value(self): 
63              return self._value 
64   
65 -    class View(object): 
66 -        def __init__(self, model): 
67              self.model = model 
68              model.changed.connect(self.model_changed) 
69   
70 -        def model_changed(self): 
71              print("New value: %s" % (self.model.get_value())) 
72   
73      model = Model(10) 
74      view1 = View(model) 
75      view2 = View(model) 
76      view3 = View(model) 
77   
78      model.set_value(20) 
79      del view1 # remove one listener 
80      model.set_value(30) 
81      model.changed.clear() # remove all listeners 
82      model.set_value(40) 
83   
84      # To disconnect :  
85      # model.changed.disconnect(view1.model_changed) 
86