Subject: [boost] [shared_ptr] Two suggestions for the aliasing constructor
From: Clive Jones (clive-boost_at_[hidden])
Date: 2008-12-06 09:07:57
1) An aliasing constructor that takes an rvalue reference
Motivating example: in my code I have a utility function...
template <typename T, typename Y>
boost::shared_ptr<T> shared_ptr_to_member(const boost::shared_ptr<Y> &ptr,
return boost::shared_ptr<T>(ptr, &(ptr.get()->*ptr_to_member));
...which seems to me a prime candidate for having an overload that
takes an rvalue reference.
The implementation would be very simple, by direct analogy with the
existing aliasing constructor and rvalue constructor.
template< class Y >
shared_ptr( shared_ptr<Y> && r, T * p ): px( p ), pn() // never throws
pn.swap( r.pn );
r.px = 0;
2) Refactor the pointer_cast functions to use the aliasing constructor
The pointer casting functions were implemented before the aliasing
constructor was available; using it, simpler implementation is
possible. For example, rewriting static_pointer_cast as:
template<class T, class U> shared_ptr<T> static_pointer_cast(shared_ptr<U> const & r)
return shared_ptr<T>(r, static_cast<T *>(r.get()));
...allows the removal of boost::detail::static_cast_tag and the
shared_ptr constructor that accepts it.
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