fixed bug where std_fgraph was populated with Feature subclasses instead

theano/compile/function_module.py

@@ -148,7 +148,7 @@ def std_fgraph(input_specs, output_specs, accept_inplace = False):
     return fgraph, map(SymbolicOutput, updates)
 
 
-std_fgraph.features = [gof.toolbox.PreserveNames]
+std_fgraph.features = [gof.toolbox.PreserveNames()]
 
 class UncomputableFeature(gof.Feature):
     """A feature that ensures the graph never contains any
@@ -165,7 +165,7 @@ class UncomputableFeature(gof.Feature):
     def on_import(self, fgraph, node):
         gof.op.raise_if_uncomputable(node)
 
-std_fgraph.features.append(UncomputableFeature)
+std_fgraph.features.append(UncomputableFeature())
 
 
 class AliasedMemoryError(Exception):

theano/gof/fg.py

@@ -440,6 +440,13 @@ class FunctionGraph(utils.object2):
         """
         if feature in self._features:
             return # the feature is already present
+
+        #it would be nice if we could require a specific class instead of
+        #a "workalike" so we could do actual error checking
+        #if not isinstance(feature, toolbox.Feature):
+        #    raise TypeError("Expected gof.toolbox.Feature instance, got "+\
+        #            str(type(feature)))
+
         attach = getattr(feature, 'on_attach', None)
         if attach is not None:
             try:

theano/gof/toolbox.py

@@ -317,6 +317,7 @@ class PrintListener(Feature):
 
 
 class PreserveNames(Feature):
+
     def on_change_input(self, fgraph, mode, i, r, new_r, reason=None):
         if r.name is not None and new_r.name is None:
             new_r.name = r.name