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From: Mark Wilden <Mark@mWilden.com>
Subject: Re: Q: virtual functions not overridable anymore?
Date: 1997/09/18
Message-ID: <3420858D.12DB@mWilden.com>#1/1
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Valentin Bonnard wrote:
> 
> Let's say you have the following GUI classes:
> 
> class Window {
>     virtual void draw () = 0;
> };
> 
> class Dialog {
>     void draw ()
>     {
>         for_each (items.begin (), items.end (),
>                   ptr_mem_fun (DialogItem::draw));
>     }
>     list<DialogItem> items;
> };
> 
> class DialogItem {
>     virtual void draw () = 0;
> };
> 
> You might want to declare Dialog::draw () final as at this point,
> behaviour should be changed by deriving from DialogItem, not Dialog.

That would prevent you from doing something like this:

 struct DebugDialog : Dialog {
    void draw()
    {
        cout << "About to draw dialog" << endl;
        Dialog::draw();
        cout << "Done drawing dialog" << endl;
    }
 };
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