Rename and refactor subtensor.make_constant

theano/tensor/opt.py

@@ -50,7 +50,7 @@ from theano.tensor.subtensor import (
     get_canonical_form_slice,
     Subtensor,
     IncSubtensor,
-    make_constant,
+    as_index_constant,
     AdvancedIncSubtensor1,
     AdvancedIncSubtensor,
     AdvancedSubtensor1,
@@ -3388,7 +3388,7 @@ def local_subtensor_merge(node):
             else:
                 merged_slices += slices1[pos_1:]
 
-            merged_slices = make_constant(merged_slices)
+            merged_slices = tuple(as_index_constant(s) for s in merged_slices)
             subtens = Subtensor(merged_slices)
 
             sl_ins = Subtensor.collapse(

theano/tensor/subtensor.py

@@ -51,21 +51,25 @@ class AdvancedBooleanIndexingError(TypeError):
     pass
 
 
-def make_constant(args):
-    """Convert Python literals to Theano constants in Subtensor arguments."""
-
-    def conv(a):
-        if a is None:
-            return a
-        elif isinstance(a, slice):
-            return slice(conv(a.start), conv(a.stop), conv(a.step))
-        elif isinstance(a, (integer_types, np.integer)):
-            return scal.ScalarConstant(scal.int64, a)
-        else:
-            # Use `tensor.scalar_from_tensor`?
-            return a
+def as_index_constant(a):
+    """Convert Python literals to Theano constants--when possible--in Subtensor arguments.
 
-    return tuple(map(conv, args))
+    This will leave `Variable`s untouched.
+    """
+    if a is None:
+        return a
+    elif isinstance(a, slice):
+        return slice(
+            as_index_constant(a.start),
+            as_index_constant(a.stop),
+            as_index_constant(a.step),
+        )
+    elif isinstance(a, (integer_types, np.integer)):
+        return scal.ScalarConstant(scal.int64, a)
+    elif not isinstance(a, theano.tensor.Variable):
+        return theano.tensor.as_tensor(a)
+    else:
+        return a
 
 
 def get_idx_list(inputs, idx_list, get_count=False):
@@ -277,7 +281,9 @@ def range_len(slc):
     """
     from theano.tensor import switch, and_, lt, gt
 
-    start, stop, step = make_constant([slc.start, slc.stop, slc.step])
+    start, stop, step = tuple(
+        as_index_constant(a) for a in [slc.start, slc.stop, slc.step]
+    )
     return switch(
         and_(gt(step, 0), lt(start, stop)),
         1 + (stop - 1 - start) // step,

theano/tensor/var.py

@@ -545,14 +545,16 @@ class _tensor_py_operators(object):
 
         # Force input to be int64 datatype if input is an empty list or tuple
         # Else leave it as is if it is a real number
+        # Convert python literals to theano constants
         args = tuple(
             [
-                np.array(inp, dtype=np.int64) if (is_empty_array(inp)) else inp
+                theano.tensor.subtensor.as_index_constant(
+                    np.array(inp, dtype=np.int64) if is_empty_array(inp) else inp
+                )
                 for inp in args
             ]
         )
-        # Convert python literals to theano constants
-        args = theano.tensor.subtensor.make_constant(args)
+
         # Determine if advanced indexing is needed or not
         # The logic is already in Subtensor.convert: if it succeeds,
         # standard indexing is used; if it fails with