Re: Multiple inheritance with only one virtual base destructor
On Apr 27, 9:15 pm, Christian Hackl <h...@sbox.tugraz.at> wrote:
Does the following code produce undefined behaviour?
class Base
{
public:
virtual ~Base();
/* ... */
};
class BaseWithNonVirtualDestructor
{
protected:
~BaseWithNonVirtualDestructor();
/* ... */
}
class Derived : public Base, public BaseWithNonVirtualDestructor
{
public:
/* ... */
};
int main()
{
Base *ptr = new Derived;
delete ptr;
}
May you also point me to the section of the standard which defines the
behaviour of such MI constructs in conjunction with virtual destructors?
Victor has answered the exact question. In fact, multiple
inheritance has nothing to do with it; if the static type of the
pointed to object in the delete has a virtual destructor, you're
OK; if it doesn't you're not.
For my current problem, by the way, BaseWithNonVirtualDestructor is
actually boost::noncopyable, which I would like to use in this manner.
Presumably, it makes no sense for people to manipulate your
object using boost::noncopyable*. So why not inherit privately
from the class, so they can't (except by means of a C-style
cast)? As your class now stands:
BaseWithNonVirtualDestructor* p = new Derived ;
delete p ;
*is* undefined behavior, and doesn't solitict the slightest
complaint on the part of the compiler.
--
James Kanze (Gabi Software) email: james.kanze@gmail.com
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