Add dtype arg to ScalarVariable.zeros_like

theano/scalar/basic.py

@@ -579,9 +579,11 @@ class _scalar_py_operators:
     def __rpow__(self, other):
         return pow(other, self)
 
-    def zeros_like(self):
+    def zeros_like(self, dtype=None):
         # The second is needed for Elemwise ops to work right
-        return second(self, ScalarConstant(Scalar(str(self.type.dtype)), 0))
+        if dtype is None:
+            dtype = str(self.type.dtype)
+        return second(self, ScalarConstant(Scalar(dtype), 0))
 
     def astype(self, dtype):
         return cast(self, dtype)