Scott McMurray wrote:
I'm not convinced that this is useful. It doesn't protect against real nulls of pointer type
Yes, you would have to assume that whenever you're initializing from a pointer, that pointer points to a valid object. A possible alternative way to solve that problem would be to make the constructor private, only accessible by boost::addressof which would be used instead of &. Since you would apply adressof on an object (and thus moving the requirement that the object is valid to the user), you cannot end up with a null pointer. boost::ref is actually quite similar to that.
and if I see a failure talking about int when I want a null pointer, my first instinct would be to assume it's an overload or deduction error, and just cast it, at which point it will compile.
If you cast, you're dropping type safety, so you're on your own. A code that performs casting, outside of low-level coding or a few idioms like CRTCP, is a bad thing.