in reply to Implementing a Mixin Class
I don't really think a consensus has been reached. I'd probably use your first multiple-inheritance based option myself.
Your second and third options are really the same thing. Exporter is just a standard mechanism for supplying import based symbol table fiddling.
Perl 6 is looking to generalise "mixin" type behaviour a bit with Traits (called 'roles' in Perl 6). You might want to take a look at some of the Perl 5 implementations of this strategy (Class::Role, Class::Roles, Class::Trait).