Think of it in the case of a subclass specializing the _behavior_ of the superclass. And if you wanted to do that _without_ knowing too much about the internals of the superclass, how to do that without tromping all over some data the superclass needs.

That said, if you wanted to specialize behavior without accidents, it might be better to use has-a rather than is-a.

In reply to Re: subclass data clobbering superclass data by shenme
in thread subclass data clobbering superclass data by princepawn

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