Re: [Boost-users] shared_ptr vs ordinary pointers

From: Peter Dimov (pdimov_at_[hidden])
Date: 2005-11-26 14:21:19

Merrill Cornish wrote:
> With an ordinary C++ pointer, if I have a BaseClass and a
> DerivedClass derived from BaseClass, then I can do
> 
>    BaseClass* objectPtr;
>    objectPtr = new DerivedClass();
> 
> Later, if BaseClass has a virtual destructor, I can call
> delete(objectPtr) and the DerivedClass destructor will be called.
> 
> Now, does this work with shared_ptr?
> 
>    shared_ptr<BaseClass> objectPtr;
>    objectPtr = shared_ptr<DerivedClass>(new DerivedClass());

Yes, it does. It will work even without a virtual destructor.

> and later, delete(objectPtr).

This doesn't work.

> Does any of the magic going on behind the scenes prevent shared_ptrs
> from being used like this?

Of course not. :-)