If I have the following 3 classes to hide the data type and store information, do I need a virtual destructor? I was led to believe no, but now I am not sure. I would rather not include it if possible for preformance reasons. Classes stripped down for example sake.
#include <memory>
class DarkHideInterface
{
public:
bool test;
};
template <typename T>
class DarkHideInterfaceImpl : public DarkHideInterface
{
public:
DarkHideInterfaceImpl (const T& t ) : _t(t) {}
private:
T _t;
};
class DarkHide
{
public:
template <class T> DarkHide (const T& t) : p_(new DarkHideInterfaceImpl<T>(t) ) { }
private:
std::auto_ptr<DarkHideInterface> p_;
};
With auto_ptr, I think you need the virtual destructor, since the delete will happen polymorphically - in other words, internally auto_ptr will ultimately call delete on the stored DarkHideInterface*. If DarkHideInterface doesn't have a virtual destructor and the pointer points to a DarkHideInterfaceImpl instance, then you get undefined behaviour.
Note that you wouldn't need a virtual destructor with shared_ptr as far as I know, because that remembers the type of the pointer with which it was constructed and calls delete on that pointer directly (search for 'virtual destructor' here to see what I mean: http://www.boost.org/doc/libs/1_47_0/libs/smart_ptr/shared_ptr.htm).