>>>>> "Mathieu" == Mathieu Bouchard <matju / sympatico.ca> writes:

Mathieu> In Ruby, A == B means it's _the_ same class, and A < B means
Mathieu> all objects that inherit from A also inherit from B, that is,
Mathieu> the set of A objects is smaller than the set of B objects.

That's exactly my problem : A is a subset of B. A subset of objects: a
A object is always a B object, the opposite is not necessary true. My
first post was about the lack of this concept in Ruby: dynamic typing
prevents it as an A object may become, say, an Integer. As beginner in
Ruby, the surprise comes from the fact that the OOP is ok as long as
we stay at the class level but disappears when we come to instances
(object) because of dynamic typing. This trouble comes from my
experience with strong typing languages.
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