list of expandable types used by scan for shared variables

theano/compile/ops.py

@@ -179,3 +179,7 @@ class DeepCopyOp(gof.Op):
 
 
 deep_copy_op = DeepCopyOp()
+
+# List of Theano Types that one can add an extra dimension and for which
+# Scan can deal with.
+expandable_types = ()

theano/sandbox/cuda/type.py

@@ -411,6 +411,7 @@ class CudaNdarrayType(Type):
     def c_compile_args(self):
         return []
 
+theano.compile.ops.expandable_types += (CudaNdarrayType,)
 
 # Register C code for ViewOp on CudaNdarrayType
 theano.compile.register_view_op_c_code(

theano/scan_module/scan.py

@@ -53,6 +53,7 @@ from theano.tensor import opt
 from theano import tensor
 from theano import config
 from theano.updates import Updates
+from theano.compile import ops
 
 
 import scan_op
@@ -849,7 +850,7 @@ def scan(fn,
             new_var = safe_new(input.variable)
             if getattr(input.variable, 'name', None) is not None:
                 new_var.name = input.variable.name + '_copy'
-            if isinstance(new_var.type, tensor.TensorType):
+            if isinstance(new_var.type, ops.expandable_types):
                 sit_sot_inner_inputs.append(new_var)
                 sit_sot_scan_inputs.append(
                     scan_utils.expand(

theano/tensor/basic.py

@@ -1076,6 +1076,7 @@ class TensorType(Type):
         """
         return numpy.zeros(shape, dtype=self.dtype)
 
+theano.compile.ops.expandable_types += (TensorType,)
 
 # Register TensorType C code for ViewOp.
 theano.compile.register_view_op_c_code(