Re: [boost] Proposal: null pointer class

Subject: Re: [boost] Proposal: null pointer class
From: Stewart, Robert (Robert.Stewart_at_[hidden])
Date: 2009-06-15 15:35:49

Simonson, Lucanus J
On Monday, June 15, 2009 3:21 PM
> Martin Törnwall wrote:
> >
> > I'd like to propose the inclusion of a null_ptr class in Boost.
> > template<typename T> class null_ptr
> > {
> > public:
> >    operator T*() const
> >    {
> >        return reinterpret_cast<T *>(0);
> >    }
> > };

reinterpret_cast isn't needed here.  Just return 0.

> Why not make it even simpler and more general.
>
> template <typename T>
> T null() {return T(); }
>
> int main()
> {
>    func(NULL);
>    func(null<char*>());
> }

Presumably, you meant for null() to return T *.  However, that doesn't address the overloading ambiguities that can result when overloading on int and char *, for example.  That's why a new type is needed.

_____
Rob Stewart                           robert.stewart_at_[hidden]
Software Engineer, Core Software      using std::disclaimer;
Susquehanna International Group, LLP  http://www.sig.com

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