Fixing pyblish#219

mottosso · Aug 11, 2015 · de2e90b · de2e90b
1 parent 17f1ca0
commit de2e90b
Showing 1 changed file with 5 additions and 2 deletions.
diff --git a/pyblish/plugin.py b/pyblish/plugin.py
@@ -573,12 +573,15 @@ def __init__(self, *args, **kwargs):
         self._children = dict()
 
     def add(self, other):
-        super(Context, self).add(other)
+        if other in self:
+            raise ValueError("\"%s\" already in Context" % other)
+
         self._children[other.id] = other
+        super(Context, self).add(other)
 
     def remove(self, other):
-        super(Context, self).remove(other)
         self._children.pop(other.id)
+        super(Context, self).remove(other)
 
     def create_instance(self, name, **kwargs):
         """Convenience method of the following.