create_parameterized_type_constraint is not a method.

Moose::Util::TypeConstraints->create_parameterized_type_constraint(...
+)
[download]

should be

Moose::Util::TypeConstraints::create_parameterized_type_constraint(...
+)
[download]

I wonder what purpose calling create_parameterized_type_constraint would have. Maybe it has side-effects?

I think you can delete both the "old" way and the commented way.