Added hscommon repo as a subtree

hscommon/notify.py

@@ -0,0 +1,69 @@
+# Copyright 2013 Hardcoded Software (http://www.hardcoded.net)
+
+# This software is licensed under the "BSD" License as described in the "LICENSE" file, 
+# which should be included with this package. The terms are also available at 
+# http://www.hardcoded.net/licenses/bsd_license
+
+from collections import defaultdict
+
+class Broadcaster:
+    def __init__(self):
+        self.listeners = set()
+    
+    def add_listener(self, listener):
+        self.listeners.add(listener)
+    
+    def notify(self, msg):
+        for listener in self.listeners.copy(): # listeners can change during iteration
+            if listener in self.listeners: # disconnected during notification
+                listener.dispatch(msg)
+    
+    def remove_listener(self, listener):
+        self.listeners.discard(listener)
+    
+
+class Listener:
+    def __init__(self, broadcaster):
+        self.broadcaster = broadcaster
+        self._bound_notifications = defaultdict(list)
+    
+    def bind_messages(self, messages, func):
+        """Binds multiple message to the same function.
+        
+        Often, we perform the same thing on multiple messages. Instead of having the same function
+        repeated again and agin in our class, we can use this method to bind multiple messages to
+        the same function.
+        """
+        for message in messages:
+            self._bound_notifications[message].append(func)
+    
+    def connect(self):
+        self.broadcaster.add_listener(self)
+    
+    def disconnect(self):
+        self.broadcaster.remove_listener(self)
+    
+    def dispatch(self, msg):
+        if msg in self._bound_notifications:
+            for func in self._bound_notifications[msg]:
+                func()
+        if hasattr(self, msg):
+            method = getattr(self, msg)
+            method()
+    
+
+class Repeater(Broadcaster, Listener):
+    REPEATED_NOTIFICATIONS = None
+    
+    def __init__(self, broadcaster):
+        Broadcaster.__init__(self)
+        Listener.__init__(self, broadcaster)
+    
+    def _repeat_message(self, msg):
+        if not self.REPEATED_NOTIFICATIONS or msg in self.REPEATED_NOTIFICATIONS:
+            self.notify(msg)
+    
+    def dispatch(self, msg):
+        Listener.dispatch(self, msg)
+        self._repeat_message(msg)
+