I have taken over some code that boils down to
///begin code
#include <iostream>
#include
struct base {
int i;
base(int i_):i(i_) {}
};
struct derived : base
{
derived(int i): base(i) {}
};
int main()
{
boost::shared_ptr<derived> pd(new derived(5));
void* ptr_to_pd = &pd;
boost::shared_ptr<base>* ptr_to_pb
= static_cast< boost::shared_ptr<base>* >(ptr_to_pd);
std::cout << "\n" << (**ptr_to_pb).i ; //Prints 5
}
///End code
Now shared_ptr<B> and shared_ptr<A> are unrelated types, so IIUC there
is no guarantee that this will work. Is that right? I know from the
shared_ptr documentation that I should refactor in the direction of
dynamic_ptr_cast (though complications not shown in the code above make
that harder that). However for the time being this code appears to be
working. Is that just a fluke? I.e. I am relying on the author of
boost::shared_ptr and/or my compiler creators not to do something such
that it doesn't work. Is there the possibility that any memory could be
deleted twice? Or I am worrying over nothing and in fact there is a
reason why the above is safe?
Many thanks for any advice you can provide,
Peter Bartlett
