Source Code for Module smartcard.Observer

 1  """ 
 2  from Thinking in Python, Bruce Eckel 
 3  http://python-3-patterns-idioms-test.readthedocs.org/en/latest/Observer.html 
 4   
 5  (c) Copyright 2008, Creative Commons Attribution-Share Alike 3.0. 
 6   
 7  Class support for "observer" pattern. 
 8   
 9  The observer class is the base class 
10  for all smartcard package observers. 
11   
12  Known subclasses: L{smartcard.ReaderObserver} 
13   
14  """ 
15   
16  from smartcard.Synchronization import * 
17   
18   
19 -class Observer(object): 
20   
21 -    def update(observable, arg): 
22          '''Called when the observed object is 
23          modified. You call an Observable object's 
24          notifyObservers method to notify all the 
25          object's observers of the change.''' 
26          pass 
27   
28   
29 -class Observable(Synchronization): 
30   
31 -    def __init__(self): 
32          self.obs = [] 
33          self.changed = 0 
34          Synchronization.__init__(self) 
35   
36 -    def addObserver(self, observer): 
37          if observer not in self.obs: 
38              self.obs.append(observer) 
39   
40 -    def deleteObserver(self, observer): 
41          self.obs.remove(observer) 
42   
43 -    def notifyObservers(self, arg=None): 
44          '''If 'changed' indicates that this object 
45          has changed, notify all its observers, then 
46          call clearChanged(). Each observer has its 
47          update() called with two arguments: this 
48          observable object and the generic 'arg'.''' 
49   
50          self.mutex.acquire() 
51          try: 
52              if not self.changed: 
53                      return 
54              # Make a local copy in case of synchronous 
55              # additions of observers: 
56              localArray = self.obs[:] 
57              self.clearChanged() 
58          finally: 
59              self.mutex.release() 
60          # Update observers 
61          for observer in localArray: 
62              observer.update(self, arg) 
63   
64 -    def deleteObservers(self): 
65              self.obs = [] 
66   
67 -    def setChanged(self): 
68              self.changed = 1 
69   
70 -    def clearChanged(self): 
71              self.changed = 0 
72   
73 -    def hasChanged(self): 
74              return self.changed 
75   
76 -    def countObservers(self): 
77              return len(self.obs) 
78   
79  synchronize(Observable, 
80      "addObserver deleteObserver deleteObservers " + 
81      "setChanged clearChanged hasChanged " + 
82      "countObservers") 
83  #:~ 
84