Re: Virtual function design pattern

Hello everyone,

About the virtual function design pattern mentioned,

http://www.parashift.com/c++-faq-lite/strange-inheritance.html#faq-23.4

I do not quite understand what does this statement mean "Assuming they're
protected, they probably shouldn't be virtual: if the derived class doesn't
like the behavior in one of them, it doesn't have to call that method." Any
ideas?

I quote the whole paragraph here,

--------------------
Suppose you have the exact opposite situation from the previous FAQ, where
you have a method whose overall structure is different in each derived class,
yet it has little pieces that are the same in most (if not all) derived
classes. In this case you'd put the overall algorithm in a public virtual
that's ultimately defined in the derived classes, and the little pieces of
common code can be written once (to avoid code duplication) and stashed
somewhere (anywhere!). A common place to stash the little pieces is in the
protected part of the base class, but that's not necessary and it might not
even be best. Just find a place to stash them and you'll be fine. Note that
if you do stash them in the base class, you should normally make them
protected, since normally they do things that public users don't need/want to
do. Assuming they're protected, they probably shouldn't be virtual: if the
derived class doesn't like the behavior in one of them, it doesn't have to
call that method.