Re: inheritance is not for code-reuse (??)
"Bart Simpson" <123evergreen@terrace.com> wrote in message
news:1OudnWpXqcxMnqfbnZ2dnUVZ8qaqnZ2d@bt.com...
I remember reading on parashift recently, that "Composition is for code
reuse, inheritance is for flexibility" see
(http://www.parashift.com/c++-faq-lite/smalltalk.html#faq-30.4)
This confused me somewhat as I have always thought you get code reuse "for
free" with inheritance. Am I missing something?. Will someone care to
explain ??
I don't know for sure, can only say my own thoughts.
When a class is designed with inheritance, that's what it's designed for.
The bases and derives usually get coupled fairly tightly unless you
purposely try not to (and I guess are using Composition, whatever that is
:D ).
A base class is usually specifically designed for the types of derived
classes that will use it. Additionally, derived classes are usually
specifically designed for the base class they derive from.
The problem comes in when in another program you decide to try to reuse a
polymorphic class for another purpose. You'll usually wind up redesigning a
good portion of the base class and have to create a new derived class.
Unless you specifically design the base class to be more generic.
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