diff -r 8d941af65caf -r 77b6da96e6f1 web/lib/django/dispatch/dispatcher.py --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/web/lib/django/dispatch/dispatcher.py Wed Jun 02 18:57:35 2010 +0200 @@ -0,0 +1,237 @@ +import weakref + +from django.dispatch import saferef + +WEAKREF_TYPES = (weakref.ReferenceType, saferef.BoundMethodWeakref) + +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): + """ + Create a new signal. + + 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. + + Arguments: + + 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. + """ + from django.conf import settings + + # If DEBUG is on, check that we got a good receiver + if settings.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 argspec: + assert argspec[2] is not None, \ + "Signal receivers must accept keyword arguments (**kwargs)." + + 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. + + If weak references are used, disconnect need not be called. The receiver + will be remove from dispatch automatically. + + Arguments: + + 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 + """ + if dispatch_uid: + lookup_key = (dispatch_uid, _make_id(sender)) + else: + lookup_key = (_make_id(receiver), _make_id(sender)) + + for index in xrange(len(self.receivers)): + (r_key, _) = self.receivers[index] + if r_key == lookup_key: + del self.receivers[index] + break + + def send(self, sender, **named): + """ + Send signal from sender to all connected receivers. + + 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. + + Arguments: + + 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), ... ]. + """ + responses = [] + if not self.receivers: + return responses + + for receiver in self._live_receivers(_make_id(sender)): + response = 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. + + Arguments: + + 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 = 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) + receivers = [] + + 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: + receivers.append(receiver) + else: + receivers.append(receiver) + return receivers + + 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]