Re: Future of C++

"Bo Persson" <>
Wed, 13 Aug 2008 12:13:41 CST
Andre Kaufmann wrote:

Bo Persson wrote:

What if I never delete the derived class through a pointer to base
(I hardly ever do)? Then the virtual destructor is totally
unneeded - that's why I didn't add one in the first place, doh!
Should the compiler add one anyway, just in case?

Out of curiosity:

Aren't virtual functions used because they are called through a
pointer to the base class - I think that's what's polymorphism is
all about.

Yes, but that doesn't mean that the objects *always* have to be
destroyed polymorphically.

So the code has to deal with the base class, in
combination with smart pointers, how can it be ensured that the
object is always deleted through the derived class pointer ?

The derived class could very well be a member of a larger class, and
not be allocated dynamically. You could still call functions taking a
pointer (or reference) to the base class as a parameter.

Even if it is allocated dynamically, its creator could keep the
original pointer returned from new, and use that when calling delete.
The Boost/C++0x shared_ptr can do that for you.

But how about a compromise ?:

Wouldn't it make sense to enforce the (hidden) destructor of a base
class with virtual abstract functions to be protected automatically

At least that would probably not break code that isn't already broken.

Bo Persson

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