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On Wed, 23 May 2001, Uche Ogbuji wrote:
> > No! Polymorphism! The existing code relies on an object implementing a
> > given interface, and you can write other classes to implement that
> > interface and swap them in, you don't have to subclass the existing
> > "Customer" class.
>
> No. Inheritance. This is part of my core point: OO has a very limited
> concept of polymorphism, which is really just late binding. OO restricts
> late binding to sub-type constraints and thence sub-class function
> dispatch.
Depends what OO system you chose :-)
Sub-type can be boiled down to "provides interface X" if you use proper
interfaces / abstract classes. Providing the same interface is a pretty
minimal requirement for "interchaneability". You don't have to inherit
your proxy Customer from the original Customer object, you just have to
provide the same interface.
> My point is that you can get all the benefits of swapping in the Customer
> code without late binding tied exclusively to inheritance. IOW,
> polymorphism is much bigger than OO.
Gimmee an example, I don't totally follow you...
ABS
--
Alaric B. Snell
http://www.alaric-snell.com/ http://RFC.net/ http://www.warhead.org.uk/
Any sufficiently advanced technology can be emulated in software
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