Still looks "clumsy" to me. And you've effectively destroyed the previous "animal" everytime you activate a different one.

Now, as for the maintenance aspect ... You've created 3 program files already, and will require an additional one for each additional implementation.

As I said, it's easier with an object-oriented language.

>>Also, it doesn't seem to be particularly useful unless you have "objects" ... so there are some language dependencies. Using "scoping rules", I can affect polymorphism in a procedural language, but it's pretty clumsy.
>
>That depends on what you define as "clumsy". I used to do this in 2.6 all the time:
>
>

SET PROCEDURE TO pig
>DO speak
>
>SET PROCEDURE TO cow
>DO speak
>
>
>*pig.prg
>PROCEDURE speak
>?"Oink"
>
>*cow.prg
>PROCEDURE speak
>?"Moo"