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List:       gtkmm
Subject:    Re: [gtkmm] destroy_impl()
From:       Karl Nelson <kenelson () ece ! ucdavis ! edu>
Date:       2000-04-26 20:49:03
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> As I can undestand, destroy_impl() doesn't present. Is this bug or
> feature?

Feature.   destory_impl is a virtual function which is almost always
called from inside the dtor.  However, because of C++ specification 
calling a virtual within a dtor will not give expected results.  

Ie.

class A
  {
    virtual void destroy() { cout << "A::destroy"; };
    virtual ~A() { destroy(); }
  };

class B: public A
  {
    virtual void destroy() { cout << "B::destroy"; };
  };

{
  B b;
}

What should this give?

According to gtk+ rules I should get B::destroy, but according
to C++ I get A::destroy.  (depending on which object does first
Gtk+ or Gtk-- you will get one or the other.)

Therefore, we really couldn't place a destroy_impl without 
a lot of explaining.  It is a feature not to have it.

Does that help?

--Karl





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