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Re: subclassing LineEdit is ugly [message #2371 is a reply to message #2369]

Mon, 10 April 2006 01:48

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hojtsy wrote on Sun, 09 April 2006 22:29

luzr wrote on Sun, 09 April 2006 16:11

Ah, well, but where this should stop? Should we make all methods everywhere public and virtual? Smile

...
Returning to your question whether all methods everywhere should be virtual: I think that complex library classes should be easy to subclass, not just possible, which means to me that
1) any non-speed-critical and non-trivial methods of complex classes should be virtual, and
2) long and complex methods implementing multiple aspects of the behaviour (such as the monster Paint in several Ctrls) should be broken up to multiple virtual methods, to enable overriding only one of them

My reasoning for this is that when you are developping an application yourself and need a subclass it is very easy for you to just make the needed method virtual in the base class, or just insert a branch in the library code itself. But for the clients of the library we are stuck with the amount of flexibility which is readily provided by the library. Imaging working in an environment where you can not change the library, but required to provide slighly different behaviour in some classes. This different working method places different requirements on the library, which may not be realized by you while working on one of your own applications.

Yes, yes and yes.

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