From d8e4e5e784a96bf2f47229322daef2e9c933617f 2014-02-24 22:35:16
From: Min RK <benjaminrk@gmail.com>
Date: 2014-02-24 22:35:16
Subject: [PATCH] Merge pull request #5197 from jasongrout/traitlet-notify

If there is an error comparing traitlet values when setting a trait, default to go ahead and notify of the new value.
---

diff --git a/IPython/utils/traitlets.py b/IPython/utils/traitlets.py
index 79ba3ec..6ebda18 100644
--- a/IPython/utils/traitlets.py
+++ b/IPython/utils/traitlets.py
@@ -371,7 +371,12 @@ class TraitType(object):
         new_value = self._validate(obj, value)
         old_value = self.__get__(obj)
         obj._trait_values[self.name] = new_value
-        if old_value != new_value:
+        try:
+            notify = (old_value != new_value)
+        except:
+            # if there is an error in comparing, default to notify
+            notify = True
+        if notify:
             obj._notify_trait(self.name, old_value, new_value)
 
     def _validate(self, obj, value):