Well, suppose you have a class MyObject and you want to add to it some
methods to make its instances into a database. You could put these
methods into another class called Storable (the mixin class).
Then you can mix MyObject with Storable and get what you want,
a class StorableObject inheriting both from Storable and MyObject.
Of course you can reuse Storable to make storable even other
classes, for instance you could define a StorableOtherObject
inheriting from OtherObject and Storable.
Once in a time, I thought mixins where a good idea; now I don't think
so since they are too easily abused (see Zope 2) and as a consequence
you get spaghetti-inheritance, where you have objects with methods
inherited from everywhere. So be very careful if you want to use
mixins; often you can go without them.
Just my 2 Euro cents,
Michele Simionato
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