Yes, exactly. There has been much discussion of this over the years (I've been an advocate). They are so similar that they beg to be unified -- but it is tricky to go all the way with it. Note (a) that the methods etc., of a Class then become the characteristic function of the set, and (b) that an object could be in many Set/Classes -- i.e. there is a very interesting and useful way to think about multiple inheritance here. Also, one could think of what happens to an object if one forces it into a particular set. And there is the nice notion of using retrieval to define new useful Set/Classes of objects ...

Cheers,

Alan

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At 10:27 PM -0400 4/26/98, Florin Mateoc wrote:
>Why not something like:
>
>Object
>  Collection
>    Bag
>      Array
>      ...
>    Set
>      Class
>
>so why isn't Class a Set ?