Extend CLinkerType with new abstract method `c_element_type()`.

theano/gof/type.py

@@ -35,6 +35,19 @@ class CLinkerType(CLinkerObject):
 
     """
 
+    def c_element_type(self):
+        """
+        Optional: Return the name of the primitive C type of items into variables
+        handled by this type.
+
+        e.g:
+
+         - For ``TensorType(dtype='int64', ...)``: should return ``"npy_int64"``.
+         - For ``GpuArrayType(dtype='int32', ...)``: should return ``"ga_int"``.
+
+        """
+        return ''
+
     def c_is_simple(self):
         """
         Optional: Return True for small or builtin C types.

theano/gpuarray/type.py

@@ -430,6 +430,9 @@ class GpuArrayType(Type):
         else:
             return np.dtype(self.dtype).itemsize
 
+    def c_element_type(self):
+        return pygpu.gpuarray.dtype_to_ctype(self.dtype)
+
     def c_declare(self, name, sub, check_input=True):
         return """
         PyGpuArrayObject *%(name)s;

theano/scalar/basic.py

@@ -349,6 +349,9 @@ class Scalar(Type):
             return True
         return abs(diff) <= (abs(a) * tolerance) + (abs(b) * tolerance)
 
+    def c_element_type(self):
+        return self.dtype_specs()[1]
+
     def c_headers(self, c_compiler):
         l = ['<math.h>']
         # These includes are needed by Scalar and TensorType,

theano/tensor/type.py

@@ -375,6 +375,9 @@ class TensorType(Type):
         return str(self)
         # "TensorType{%s, %s}" % (str(self.dtype), str(self.broadcastable))
 
+    def c_element_type(self):
+        return self.dtype_specs()[1]
+
     def c_declare(self, name, sub, check_input=True):
         """
         Override `CLinkerType.c_declare`.