Re: Separation of API and implementation

But often hierarchies aren't not really parallel. Either X or Y could be
designed class-wide. Then you dispatch along the opposite axis and no
second dispatch (poorly emulated by a cast in your example) is needed.

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Can you give an example of this - I don't fully understand what you
mean by 'class-wide'?

In what sense is it a bad design?

Regards
Howard.

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