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   Re: [xml-dev] Stupid Question (was RE: [xml-dev] XML doesn't dese rveits

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Nicolas LEHUEN
>Well, think about extending an object.  Any object that knows
>how to talk to
>the parent also knows how to talk to the child, but only with
>the methods of
>the parent.  Of the new methods defined for the child, and its new
>properties, the older objects know nothing.  This is much like
>ignoring new
>elements and attributes in markup when the schema has been
>changed, which
>you were arguing against, saying it would be a bad idea or
>unfeasible (I
>didn't quote that part).

Hello ? Do you know what polymorphism is ? Any object that knows how to talk
with the parent will know how to talk to the child, except that the
resulting behaviour is redefined in the child. The child can take its
extended state into account when replying to a method call from the parent

Sure I know what polymorphism is.  I said the "methods of the parent" - I
should have been clear that I meant "methods with the same name and
signature as those of the parent".  That covers polymorphism as well as
literally unchanged methods, and it is what I was thinking.


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