small opt in subtensor.

theano/tensor/basic.py

@@ -2589,9 +2589,9 @@ def get_idx_list(inputs, idx_list):
     '''
 
     # The subtensor (or idx_list) does not depend on the inputs.
-    indices = list(reversed(list(inputs[1:])))
-    if len(indices) == 0:
+    if len(inputs) == 1:
         return tuple(idx_list)
+    indices = list(reversed(list(inputs[1:])))
 
     # General case
     def convert(entry):
@@ -2779,7 +2779,7 @@ class Subtensor(Op):
             raise TypeError(Subtensor.e_indextype, entry)
 
     def __init__(self, idx_list):
-        self.idx_list = map(self.convert, idx_list)
+        self.idx_list = tuple(map(self.convert, idx_list))
         self.perform_cache_cdata = None
 
     @staticmethod
@@ -2834,7 +2834,7 @@ class Subtensor(Op):
         if len(cdata) == 1:
             cdata = cdata[0]
         # (first call caches cdata here)
-        if len(inputs[1:]) == 0:
+        if len(inputs) == 1:
             self.perform_cache_cdata = cdata
 
         out[0] = numpy.asarray(x.__getitem__(cdata))