AMDG Dominique Devienne wrote:
On Wed, Apr 15, 2009 at 12:25 PM, Steven Watanabe <watanabesj@gmail.com> wrote:
Dominique Devienne wrote:
So I used covariant return type, which AFAIK works only for raw pointers. If I were to remove the raw pointer accessors, I'd have to do either:
I would probably use a non-member template that encapsulates the necessary logic:
template<class T> shared_ptr<typename T::IdentType> getIdent(T& t);
I have:
template <class T> shared_ptr<typename T::ident_type> ident_of(T* t) { BOOST_STATIC_ASSERT((is_base_of<Object, T>::value)); return static_pointer_cast<typename T::ident_type>(t->ident()); } template <class T> shared_ptr<typename T::ident_type const> ident_of(const T* t) { BOOST_STATIC_ASSERT((is_base_of<Object, T>::value)); return static_pointer_cast<typename T::ident_type const>(t->ident()); }
but it chokes on:
scoped_ptr<Car> z(new Car("nissan", "370Z")); ident_of(z)->set_make("datsun");
error C2784: 'boost::shared_ptr<T::ident_type> ident_of(T *)' : could not deduce template argument for 'T *' from 'boost::scoped_ptr<T>'
Instead of doing overloads for various smart pointer types, is it possible (and easy) to do the ChainedPtr thing that B.MI does for the ident_of template functions above?
Try passing the argument to ident_of by reference instead of by pointer and dereference the (smart) pointer at the call site. In Christ, Steven Watanabe