From f3be3b1195bc5b2db1bde803b83007ad79db7e01 2014-10-31 16:58:09
From: Thomas Kluyver <takowl@gmail.com>
Date: 2014-10-31 16:58:09
Subject: [PATCH] Merge pull request #6680 from njsmith/reset-warning-registry

Reset the interactive namespace __warningregistry__ before executing code
---

diff --git a/IPython/core/events.py b/IPython/core/events.py
index dcdc669..798ef01 100644
--- a/IPython/core/events.py
+++ b/IPython/core/events.py
@@ -63,14 +63,6 @@ class EventManager(object):
         """Remove a callback from the given event."""
         self.callbacks[event].remove(function)
     
-    def reset(self, event):
-        """Clear all callbacks for the given event."""
-        self.callbacks[event] = []
-    
-    def reset_all(self):
-        """Clear all callbacks for all events."""
-        self.callbacks = {n:[] for n in self.callbacks}
-    
     def trigger(self, event, *args, **kwargs):
         """Call callbacks for ``event``.
         
diff --git a/IPython/core/interactiveshell.py b/IPython/core/interactiveshell.py
index c04f925..31fa45e 100644
--- a/IPython/core/interactiveshell.py
+++ b/IPython/core/interactiveshell.py
@@ -873,6 +873,8 @@ class InteractiveShell(SingletonConfigurable):
     def init_events(self):
         self.events = EventManager(self, available_events)
 
+        self.events.register("pre_execute", self._clear_warning_registry)
+
     def register_post_execute(self, func):
         """DEPRECATED: Use ip.events.register('post_run_cell', func)
         
@@ -882,6 +884,13 @@ class InteractiveShell(SingletonConfigurable):
              "ip.events.register('post_run_cell', func) instead.")
         self.events.register('post_run_cell', func)
     
+    def _clear_warning_registry(self):
+        # clear the warning registry, so that different code blocks with
+        # overlapping line number ranges don't cause spurious suppression of
+        # warnings (see gh-6611 for details)
+        if "__warningregistry__" in self.user_global_ns:
+            del self.user_global_ns["__warningregistry__"]
+
     #-------------------------------------------------------------------------
     # Things related to the "main" module
     #-------------------------------------------------------------------------
diff --git a/IPython/core/tests/test_events.py b/IPython/core/tests/test_events.py
index e265999..8e8402c 100644
--- a/IPython/core/tests/test_events.py
+++ b/IPython/core/tests/test_events.py
@@ -25,22 +25,8 @@ class CallbackTests(unittest.TestCase):
         self.em.trigger('ping_received')
         self.assertEqual(cb.call_count, 1)
     
-    def test_reset(self):
-        cb = Mock()
-        self.em.register('ping_received', cb)
-        self.em.reset('ping_received')
-        self.em.trigger('ping_received')
-        assert not cb.called
-    
-    def test_reset_all(self):
-        cb = Mock()
-        self.em.register('ping_received', cb)
-        self.em.reset_all()
-        self.em.trigger('ping_received')
-        assert not cb.called
-    
     def test_cb_error(self):
         cb = Mock(side_effect=ValueError)
         self.em.register('ping_received', cb)
         with tt.AssertPrints("Error in callback"):
-            self.em.trigger('ping_received')
\ No newline at end of file
+            self.em.trigger('ping_received')
diff --git a/IPython/core/tests/test_interactiveshell.py b/IPython/core/tests/test_interactiveshell.py
index 4d95a68..1e8bfae 100644
--- a/IPython/core/tests/test_interactiveshell.py
+++ b/IPython/core/tests/test_interactiveshell.py
@@ -301,7 +301,10 @@ class InteractiveShellTestCase(unittest.TestCase):
             assert post_explicit.called
         finally:
             # remove post-exec
-            ip.events.reset_all()
+            ip.events.unregister('pre_run_cell', pre_explicit)
+            ip.events.unregister('pre_execute', pre_always)
+            ip.events.unregister('post_run_cell', post_explicit)
+            ip.events.unregister('post_execute', post_always)
     
     def test_silent_noadvance(self):
         """run_cell(silent=True) doesn't advance execution_count"""
@@ -840,3 +843,17 @@ class TestSyntaxErrorTransformer(unittest.TestCase):
 
 
 
+def test_warning_suppression():
+    ip.run_cell("import warnings")
+    try:
+        with tt.AssertPrints("UserWarning: asdf", channel="stderr"):
+            ip.run_cell("warnings.warn('asdf')")
+        # Here's the real test -- if we run that again, we should get the
+        # warning again. Traditionally, each warning was only issued once per
+        # IPython session (approximately), even if the user typed in new and
+        # different code that should have also triggered the warning, leading
+        # to much confusion.
+        with tt.AssertPrints("UserWarning: asdf", channel="stderr"):
+            ip.run_cell("warnings.warn('asdf')")
+    finally:
+        ip.run_cell("del warnings")