[PRL] AOP questions

[Doug Orleans]

Joe Marshall writes:
 > Lisp allows multiple `dominant structures' to co-exist in a way
 > that other languages (like Java) do not.

I think this is a red herring, or else just plain false.  If you're
using MzLib classes, the class hierarchy imposes a dominant structure.
If you want to add a method to an existing class, you have to modify
that class definition, or else make a new class that inherits from (or
delegates to) the old one and then arrange for the rest of the program
to use the new class in place of the old one.  (Or you could make a
procedure for the new functionality, but then you wouldn't have
polymorphism and inheritance.)

If you're using Swindle, though, you can just define a new method for
a generic function and nothing else needs to be modified.
I.e. Swindle supports incremental development in a way that MzLib's
classes don't.  But there are other things you can't do in Swindle
either (without going into the MOP).

--Doug