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From: Bronek Kozicki (brok_at_[hidden])
Date: 2004-08-27 10:49:00

Howard Hinnant wrote:
>> So that sizeof(move_ptr<T>) can be the same as sizeof(T*).
> Yes, yes! Absolutely zero-overhead over a raw pointer is (imho) a
> critical design criteria of this type of smart pointer. And the reason
> for the ::type dance instead of something more direct like:
> template<class T, class D = detail::default_delete<T> >

OK, I guess that detail::default_delete<T> is going to be stored as
static field of move_ptr class. However ...

> 2. And the deleter itself should be able to be a reference type.
> I can't stress this second point enough. It is a real feature when you
> want to allow for the possibility of a deleter that is both state-full
> and heavy. In templated code that already owns a deleter (that you
> don't know anything about, except its name), and you're using the
> move_ptr just to enforce ownership temporarily (say for exception safety
> purposes), then passing a reference-typed deleter to the move_ptr is an
> extremely elegant solution:
> Code templated on P (p : pointer type) and D (d_ : deleter type):
> move_ptr<P, D&> hold(p, d_); // grab hold of p, using a D&, as
> opposed to a D

... how are you going to store reference to deleter object here, without
any memory overhead in your pointer object?


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