Re: EIEIO: A question about interfaces

[Stefan Monnier]

[ Side note; I'm a functional programmer, so OO design is not something
  I'm good at.  Also, while I am familiar with the CLOS features and
  semantics, I don't have much experience using it.  ]

> Now I want to allow that some objects of some of these classes have/
> support an additional feature.

I think the idea is that those objects which support that extra feature
aren't really of the same type as those that don't, so you'd create
a new class for them.

In your example, that might mean you'd create a new class that inherits
from both `my-1` and `my-foo-interface`.

Of course, another approach is to not use the OO approach to
solve this problem but instead to use good'ol `if` tests, tho you'll
still need to store that `additional` info somewhere: you could add some
`extra-properties` to all your objects and store it there, tho depending
on the specifics there are likely to be various other options.


        Stefan