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On Sun, 2007-10-07 at 07:18 +0900, Austin Ziegler wrote:
> What Mentalguy's suggesting is that the relationships may not be best
> modeled as an is-a relationship, as I suggested to Trans early on in
> the discussion. Is-a relationships are very tightly coupled and should
> only be used where such a tight relationship is warranted.

Also, even when you have a true "is-a" relationship, "is-a" in the class
domain doesn't always correspond to "is-a" in the domain being modeled.=20

This is because the requirements of dynamic method dispatch introduce
additional constraints on subclassing which violate some of the laws a
simple transitive relationship like "is-a" might reasonably be expected
to obey.

Single-inheritance is an obvious example of one such constraint, but
allowing multiple inheritance simply means replacing that constraint
with others.

-mental

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