Merge pull request matplotlib#4118 from OceanWolf/callback-registry-fix

BUG : CallbackRegistry fix

Correctly proxy instance methods.

Author: tacaswell

lib/matplotlib/cbook.py

@@ -361,9 +361,14 @@ class _BoundMethodProxy(object):
     Minor bugfixes by Michael Droettboom
     '''
     def __init__(self, cb):
+        self._hash = hash(cb)
+        self._destroy_callbacks = []
         try:
             try:
-                self.inst = ref(cb.im_self)
+                if six.PY3:
+                    self.inst = ref(cb.__self__, self._destroy)
+                else:
+                    self.inst = ref(cb.im_self, self._destroy)
             except TypeError:
                 self.inst = None
             if six.PY3:
@@ -377,6 +382,16 @@ def __init__(self, cb):
             self.func = cb
             self.klass = None
 
+    def add_destroy_callback(self, callback):
+        self._destroy_callbacks.append(_BoundMethodProxy(callback))
+
+    def _destroy(self, wk):
+        for callback in self._destroy_callbacks:
+            try:
+                callback(self)
+            except ReferenceError:
+                pass
+
     def __getstate__(self):
         d = self.__dict__.copy()
         # de-weak reference inst
@@ -433,6 +448,9 @@ def __ne__(self, other):
         '''
         return not self.__eq__(other)
 
+    def __hash__(self):
+        return self._hash
+
 
 class CallbackRegistry(object):
     """
@@ -492,17 +510,32 @@ def connect(self, s, func):
         func will be called
         """
         self._func_cid_map.setdefault(s, WeakKeyDictionary())
-        if func in self._func_cid_map[s]:
-            return self._func_cid_map[s][func]
+        # Note proxy not needed in python 3.
+        # TODO rewrite this when support for python2.x gets dropped.
+        proxy = _BoundMethodProxy(func)
+        if proxy in self._func_cid_map[s]:
+            return self._func_cid_map[s][proxy]
 
+        proxy.add_destroy_callback(self._remove_proxy)
         self._cid += 1
         cid = self._cid
-        self._func_cid_map[s][func] = cid
+        self._func_cid_map[s][proxy] = cid
         self.callbacks.setdefault(s, dict())
-        proxy = _BoundMethodProxy(func)
         self.callbacks[s][cid] = proxy
         return cid
 
+    def _remove_proxy(self, proxy):
+        for signal, proxies in list(six.iteritems(self._func_cid_map)):
+            try:
+                del self.callbacks[signal][proxies[proxy]]
+            except KeyError:
+                pass
+
+            if len(self.callbacks[signal]) == 0:
+                del self.callbacks[signal]
+                del self._func_cid_map[signal]
+
+
     def disconnect(self, cid):
         """
         disconnect the callback registered with callback id *cid*
@@ -513,7 +546,7 @@ def disconnect(self, cid):
             except KeyError:
                 continue
             else:
-                for category, functions in list(
+                for signal, functions in list(
                         six.iteritems(self._func_cid_map)):
                     for function, value in list(six.iteritems(functions)):
                         if value == cid:
@@ -527,11 +560,10 @@ def process(self, s, *args, **kwargs):
         """
         if s in self.callbacks:
             for cid, proxy in list(six.iteritems(self.callbacks[s])):
-                # Clean out dead references
-                if proxy.inst is not None and proxy.inst() is None:
-                    del self.callbacks[s][cid]
-                else:
+                try:
                     proxy(*args, **kwargs)
+                except ReferenceError:
+                    self._remove_proxy(proxy)
 
 
 class Scheduler(threading.Thread):

lib/matplotlib/tests/test_cbook.py

@@ -8,7 +8,7 @@
 import numpy as np
 from numpy.testing.utils import (assert_array_equal, assert_approx_equal,
                                  assert_array_almost_equal)
-from nose.tools import assert_equal, raises, assert_true
+from nose.tools import assert_equal, assert_not_equal, raises, assert_true
 
 import matplotlib.cbook as cbook
 import matplotlib.colors as mcolors
@@ -243,3 +243,47 @@ def test_label_error(self):
     def test_bad_dims(self):
         data = np.random.normal(size=(34, 34, 34))
         results = cbook.boxplot_stats(data)
+
+
+class Test_callback_registry(object):
+    def setup(self):
+        self.signal = 'test'
+        self.callbacks = cbook.CallbackRegistry()
+
+    def connect(self, s, func):
+        return self.callbacks.connect(s, func)
+
+    def is_empty(self):
+        assert_equal(self.callbacks._func_cid_map, {})
+        assert_equal(self.callbacks.callbacks, {})
+
+    def is_not_empty(self):
+        assert_not_equal(self.callbacks._func_cid_map, {})
+        assert_not_equal(self.callbacks.callbacks, {})
+
+    def test_callback_complete(self):
+        # ensure we start with an empty registry
+        self.is_empty()
+
+        # create a class for testing
+        mini_me = Test_callback_registry()
+
+        # test that we can add a callback
+        cid1 = self.connect(self.signal, mini_me.dummy)
+        assert_equal(type(cid1), int)
+        self.is_not_empty()
+
+        # test that we don't add a second callback
+        cid2 = self.connect(self.signal, mini_me.dummy)
+        assert_equal(cid1, cid2)
+        self.is_not_empty()
+        assert_equal(len(self.callbacks._func_cid_map), 1)
+        assert_equal(len(self.callbacks.callbacks), 1)
+
+        del mini_me
+
+        # check we now have no callbacks registered
+        self.is_empty()
+
+    def dummy(self):
+        pass