🚀 go-pugleaf

In article <DD1MI7.C8H.0.-s@cs.vu.nl>, ctv <ctv@cs.vu.nl> wrote:
>
>Operator overloading can be used to implement so called smart
>pointers. Operator "=", "->", etcetera member functions allow
>these smart pointers to be used in (almost) the same way as real
>pointers.
>
>How to mimic real-pointer-like casts when the pointers are actually
>smart pointers ?

Member templates:

template<class T> class Smart {
T *data;
public:
template<class Q>
Smart(Smart<Q> const &arg) {
data = arg.data; // conversion!
}
..
};

struct Base {};
struct Derived : Base {};
Smart<Derived> pd = new Derived;
Smart<Base> = bd; // Smart pointer conversion!
Smart<Derived> bad = pb; // INSTANTIATION FAILS!

Note in the last line the conversion is CORRECT -- there's
no error here, the error occurs instantiating the
member template. If the body isn't visible you'd not
find out until link time.

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