Added a way to check if a signal has listeners

django · Sep 28, 2012 · 3fcca0e · 3fcca0e
1 parent 07ffe78
commit 3fcca0e
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Showing 2 changed files with 14 additions and 0 deletions.
diff --git a/django/dispatch/dispatcher.py b/django/dispatch/dispatcher.py
@@ -141,6 +141,9 @@ def disconnect(self, receiver=None, sender=None, weak=True, dispatch_uid=None):
                     del self.receivers[index]
                     break
 
+    def has_listeners(self, sender=None):
+        return bool(self._live_receivers(_make_id(sender)))
+
     def send(self, sender, **named):
         """
         Send signal from sender to all connected receivers.

diff --git a/tests/regressiontests/dispatch/tests/test_dispatcher.py b/tests/regressiontests/dispatch/tests/test_dispatcher.py
@@ -126,6 +126,17 @@ def testDisconnection(self):
         a_signal.disconnect(receiver_3)
         self._testIsClean(a_signal)
 
+    def test_has_listeners(self):
+        self.assertIs(a_signal.has_listeners(), False)
+        self.assertIs(a_signal.has_listeners(sender=object()), False)
+        receiver_1 = Callable()
+        a_signal.connect(receiver_1)
+        self.assertIs(a_signal.has_listeners(), True)
+        self.assertIs(a_signal.has_listeners(sender=object()), True)
+        a_signal.disconnect(receiver_1)
+        self.assertIs(a_signal.has_listeners(), False)
+        self.assertIs(a_signal.has_listeners(sender=object()), False)
+
 
 class ReceiverTestCase(unittest.TestCase):
     """