Re: [Boost-users] [Serialisation] Question on shared_ptr's and base/derived classes

From: David Klein (dave_chp_at_[hidden])
Date: 2007-05-02 07:34:48

Richard Damon wrote:
> One comment is that:
>
> Class A {
> }; // No virtual destructor
>
> Class B : public A {
> }
>
> shared_ptr<A>(new B)
>
> Should cause UB as the shared pointer will will eventually call delete on
> its parameter, and since A has no virtual destructor and is NOT the type the
> object was created with, you get UB.
>
> It basically boils down to the equivalent to this
>
> A* ptr = new B;
> delete ptr;
>
> which is a no-no.
>
> A NEEDS to have a virtual destructor to use it the way you are.
> Richard
>
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>
>   
Hi Richard,

actually it's ok with shared_ptr. Here is a short snip from the docs:

...
This constructor has been changed to a template in order to remember the 
actual pointer type passed. The destructor will call delete with the 
same pointer, complete with its original type, even when T does not have 
a virtual destructor, or is void.
...