Re: [boost] Cast free NULLs in algorithms

From: Michael Marcin (mike_at_[hidden])
Date: 2007-07-31 15:53:17

Chris Fairles wrote:
> This was a proposed library implementation of nullptr for c++0x from
> http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2004/n1601.pdf
> 
> const                        // this is a const object...
> class {
> public:
>   template<class T>          // convertible to any type
>     operator T*() const      // of null non-member
>     { return 0; }            // pointer...
>   template<class C, class T> // or any type of null
>     operator T C::*() const  // member pointer...
>     { return 0; }
> private:
>   void operator&() const;    // whose address can't be taken
> } nullptr = {};              // and whose name is nullptr
> 
> Very similar to your impl although I think the static_cast in yours is
> redundant. The standard says, 0, being an integral constant expression
> that evaluates to zero, is a null pointer constant which is implicitly
> convertible to a pointer type (4.10)
> 

Cute. It might be nice to have this as a Boost utility library.

Thanks for the link,

Michael Marcin