Clean up Subtensor Op and its exceptions

theano/tensor/subtensor.py

@@ -432,40 +432,8 @@ def indexed_result_shape(array_shape, indices, indices_are_shapes=False):
 
 
 class Subtensor(Op):
-    """
-    Return a subtensor view.
-
-    The inputs array is the tensor x, followed by scalar integer types.
-    TODO: WRITEME: how are the scalar integer variables formatted?
-
-    This class uses a relatively complex internal representation of the inputs
-    to remember how the input tensor x should be sliced.
-
-    idx_list: instance variable TODO: WRITEME: is this a list or a tuple?
-                                        (old docstring gives two conflicting
-                                        descriptions)
-              elements are either integers, theano scalar types, or slices.
-              one element per "explicitly named dimension"
-                TODO: WRITEME: what is an "explicitly named dimension" ?
-
-              if integer:
-                  indexes into the inputs array
-              if slice:
-                  start/stop/step members of each slice are integer indices
-                  into the inputs array or None
-                  integer indices be actual integers or theano scalar types
-
-    Note that the idx_list defines the Op, so two Subtensor instances are
-    considered to be different Ops if they have different idx_list fields.
-    This means that the entries in it are theano Types, not theano Variables.
-
-    @todo: add support for advanced tensor indexing (in Subtensor_dx too).
+    """Basic NumPy indexing operator."""
 
-    """
-
-    e_subslice = "nested slicing is not supported"
-    e_indextype = "Invalid index type or slice for Subtensor"
-    debug = 0
     check_input = False
     view_map = {0: [0]}
     _f16_ok = True
@@ -513,27 +481,29 @@ class Subtensor(Op):
             when would that happen?
 
         """
-        invalid_scal_types = [scal.float64, scal.float32, scal.float16]
-        scal_types = [scal.int64, scal.int32, scal.int16, scal.int8]
-        tensor_types = [
+        invalid_scal_types = (scal.float64, scal.float32, scal.float16)
+        scal_types = (scal.int64, scal.int32, scal.int16, scal.int8)
+        tensor_types = (
             theano.tensor.lscalar,
             theano.tensor.iscalar,
             theano.tensor.wscalar,
             theano.tensor.bscalar,
-        ]
-        invalid_tensor_types = [
+        )
+        invalid_tensor_types = (
             theano.tensor.fscalar,
             theano.tensor.dscalar,
             theano.tensor.cscalar,
             theano.tensor.zscalar,
-        ]
+        )
 
         if (
             isinstance(entry, (np.ndarray, theano.tensor.Variable))
             and hasattr(entry, "dtype")
             and entry.dtype == "bool"
         ):
-            raise AdvancedBooleanIndexingError(Subtensor.e_indextype, entry)
+            raise AdvancedBooleanIndexingError(
+                "Invalid index type or slice for Subtensor"
+            )
 
         if isinstance(entry, gof.Variable) and (
             entry.type in invalid_scal_types or entry.type in invalid_tensor_types
@@ -587,7 +557,7 @@ class Subtensor(Op):
                 "Python scalar in idx_list." "Please report this error to theano-dev."
             )
         else:
-            raise AdvancedIndexingError(Subtensor.e_indextype, entry)
+            raise AdvancedIndexingError("Invalid index type or slice for Subtensor")
 
     def get_constant_idx(
         self, inputs, allow_partial=False, only_process_constants=False, elemwise=True