--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/clients/editor/scripts/events/signal.py	Mon Jun 08 16:00:02 2009 +0000
@@ -0,0 +1,222 @@
+"""Multi-consumer multi-producer dispatching mechanism
+
+Originally based on pydispatch (BSD) http://pypi.python.org/pypi/PyDispatcher/2.0.1
+See license.txt for original license.
+
+Heavily modified for Django's purposes.
+
+Copied from django v1.1 beta 1
+Changes:
+ * Receivers aren't needed to accept any arguments
+ * _live_receivers() now work on a copy of self.receivers, which fixes a bug when
+   connecting and disconnecting during send()
+"""
+
+import weakref
+import saferef
+import pychan
+
+WEAKREF_TYPES = (weakref.ReferenceType, saferef.BoundMethodWeakref)
+
+debug = True
+
+def _make_id(target):
+    if hasattr(target, 'im_func'):
+        return (id(target.im_self), id(target.im_func))
+    return id(target)
+
+class Signal(object):
+    """Base class for all signals
+    
+    Internal attributes:
+        receivers -- { receriverkey (id) : weakref(receiver) }
+    """
+    
+    def __init__(self, providing_args=None):
+        """providing_args -- A list of the arguments this signal can pass along in
+                       a send() call.
+        """
+        self.receivers = []
+        if providing_args is None:
+            providing_args = []
+        self.providing_args = set(providing_args)
+
+    def connect(self, receiver, sender=None, weak=True, dispatch_uid=None):
+        """Connect receiver to sender for signal
+    
+        receiver -- a function or an instance method which is to
+            receive signals.  Receivers must be
+            hashable objects.
+
+            if weak is True, then receiver must be weak-referencable
+            (more precisely saferef.safeRef() must be able to create
+            a reference to the receiver).
+        
+            Receivers must be able to accept keyword arguments.
+
+            If receivers have a dispatch_uid attribute, the receiver will
+              not be added if another receiver already exists with that
+              dispatch_uid.
+
+        sender -- the sender to which the receiver should respond
+            Must either be of type Signal, or None to receive events
+            from any sender.
+
+        weak -- whether to use weak references to the receiver
+            By default, the module will attempt to use weak
+            references to the receiver objects.  If this parameter
+            is false, then strong references will be used.
+        
+        dispatch_uid -- an identifier used to uniquely identify a particular
+            instance of a receiver. This will usually be a string, though it
+            may be anything hashable.
+
+        returns None
+        """
+        
+        # If DEBUG is on, check that we got a good receiver
+        if debug:
+            import inspect
+            assert callable(receiver), "Signal receivers must be callable."
+            
+            # Check for **kwargs
+            # Not all callables are inspectable with getargspec, so we'll
+            # try a couple different ways but in the end fall back on assuming
+            # it is -- we don't want to prevent registration of valid but weird
+            # callables.
+            try:
+                argspec = inspect.getargspec(receiver)
+            except TypeError:
+                try:
+                    argspec = inspect.getargspec(receiver.__call__)
+                except (TypeError, AttributeError):
+                    argspec = None
+        
+        if dispatch_uid:
+            lookup_key = (dispatch_uid, _make_id(sender))
+        else:
+            lookup_key = (_make_id(receiver), _make_id(sender))
+
+        if weak:
+            receiver = saferef.safeRef(receiver, onDelete=self._remove_receiver)
+
+        for r_key, _ in self.receivers:
+            if r_key == lookup_key:
+                break
+        else:
+            self.receivers.append((lookup_key, receiver))
+
+    def disconnect(self, receiver=None, sender=None, weak=True, dispatch_uid=None):
+        """Disconnect receiver from sender for signal
+    
+        receiver -- the registered receiver to disconnect. May be none if
+            dispatch_uid is specified.
+        sender -- the registered sender to disconnect
+        weak -- the weakref state to disconnect
+        dispatch_uid -- the unique identifier of the receiver to disconnect
+    
+        disconnect reverses the process of connect.
+
+        If weak references are used, disconnect need not be called.
+          The receiver will be remove from dispatch automatically.
+
+        returns None
+        """
+
+        if dispatch_uid:
+            lookup_key = (dispatch_uid, _make_id(sender))
+        else:
+            lookup_key = (_make_id(receiver), _make_id(sender))
+
+        for idx, (r_key, _) in enumerate(self.receivers):
+            if r_key == lookup_key:
+                del self.receivers[idx]
+
+    def send(self, sender, **named):
+        """Send signal from sender to all connected receivers.
+
+        sender -- the sender of the signal
+            Either a specific object or None.
+    
+        named -- named arguments which will be passed to receivers.
+
+        Returns a list of tuple pairs [(receiver, response), ... ].
+
+        If any receiver raises an error, the error propagates back
+        through send, terminating the dispatch loop, so it is quite
+        possible to not have all receivers called if a raises an
+        error.
+        """
+
+        responses = []
+        if not self.receivers:
+            return responses
+
+        for receiver in self._live_receivers(_make_id(sender)):
+            response = pychan.tools.applyOnlySuitable(receiver, signal=self, sender=sender, **named)
+            responses.append((receiver, response))
+        return responses
+
+    def send_robust(self, sender, **named):
+        """Send signal from sender to all connected receivers catching errors
+
+        sender -- the sender of the signal
+            Can be any python object (normally one registered with
+            a connect if you actually want something to occur).
+
+        named -- named arguments which will be passed to receivers.
+            These arguments must be a subset of the argument names
+            defined in providing_args.
+
+        Return a list of tuple pairs [(receiver, response), ... ],
+        may raise DispatcherKeyError
+
+        if any receiver raises an error (specifically any subclass of Exception),
+        the error instance is returned as the result for that receiver.
+        """
+
+        responses = []
+        if not self.receivers:
+            return responses
+
+        # Call each receiver with whatever arguments it can accept.
+        # Return a list of tuple pairs [(receiver, response), ... ].
+        for receiver in self._live_receivers(_make_id(sender)):
+            try:
+                response = pychan.tools.applyOnlySuitable(receiver, signal=self, sender=sender, **named)
+            except Exception, err:
+                responses.append((receiver, err))
+            else:
+                responses.append((receiver, response))
+        return responses
+
+    def _live_receivers(self, senderkey):
+        """Filter sequence of receivers to get resolved, live receivers
+
+        This checks for weak references
+        and resolves them, then returning only live
+        receivers.
+        """
+        none_senderkey = _make_id(None)
+
+        for (receiverkey, r_senderkey), receiver in self.receivers[:]:
+            if r_senderkey == none_senderkey or r_senderkey == senderkey:
+                if isinstance(receiver, WEAKREF_TYPES):
+                    # Dereference the weak reference.
+                    receiver = receiver()
+                    if receiver is not None:
+                        yield receiver
+                else:
+                    yield receiver
+
+    def _remove_receiver(self, receiver):
+        """Remove dead receivers from connections."""
+
+        to_remove = []
+        for key, connected_receiver in self.receivers:
+            if connected_receiver == receiver:
+                to_remove.append(key)
+        for key in to_remove:
+            for idx, (r_key, _) in enumerate(self.receivers):
+                if r_key == key:
+                    del self.receivers[idx]