[boost] Re: move semantics

From: David Abrahams (dave_at_[hidden])
Date: 2004-04-19 08:59:58

Daniel Wallin <dalwan01_at_[hidden]> writes:

> David Abrahams wrote:
> [snip]
>  > On the other hand, with technique 2
>> I think you can't write the generic function at all, because template
>> arguments have to match exactly:
>>    template <class T>
>>    void f(const_lvalue<Y<T> > x); // can never match a Y<T> argument
>
> Isn't this true for technique 1 as well (and everything that isn't &&)?
>
>    template<class T>
>    void f(move_from<T> x);
>
> Granted, you can detect lvalues in a generic function, but that
> isn't of much use if you can't detect temporaries, no?

Are you ready for this?

  template <class T>
  void tlsink(T volatile& y)
  {
      T const& x = const_cast<T const&>(y);
  }

  template <class T>
  void tlsink(T x)
  {
      SAY("in templated move sink");
  }

This works with EDG.  GCC isn't so happy with it.  I'm not sure which
one is right, but I'm voting for EDG.  I wonder if we can get rid of
the const_cast...

-- 
Dave Abrahams
Boost Consulting
http://www.boost-consulting.com