"Diez B. Roggisch" <[EMAIL PROTECTED]> wrote: > google for gnosis utils and multimethods to see a more "oldfashioned" > implementation.
I now remember to have seen it but it requires a lot of typing to achieve it and you would call a different function name from the one you define, reducing the code clarity. > But your approach certainly is interesting - however, The idea is not new. Lisp/CLOS implements the defmethod macro which creates a generic function (i.e. a dispatcher) with the same name as the function you define: http://www.lisp.org/HyperSpec/Body/mac_defmethod.html. Actually, the defmehod macro is the base for implementing object polymorphism. > I _rarely_ need such functionality. Ususally duck-typing suits me > well. Of course, duck-typing is simple to use but the parametric polymorphism is useful when the types are unrelated. Let's say you want to implement a colour-print function which should support basic types like ints and floats as well as lists and dictionaries. In this case, and thank to the function decorations support, the code would be clearer. Another use case is to extended the functionality of a class using functions but you cannot easily modify the class or create a subclass (the objects are generated by some factory implemented in a third-party library). Of course, you might be able to get around this but parametric polymorphism could reduce the written code. This idea only needs an optimised (and deterministic) implementation for the best parameter match based on subclass-superclass relations. It can also be extended to implement polymorphism based on the parameter values (something people tried to do in C++ with complicated templates but, well, only at compilation time, with obvious drawbacks). -- Catalin -- http://mail.python.org/mailman/listinfo/python-list
