Re: [boost] Re: A mem_fn thought

From: Peter Dimov (pdimov_at_[hidden])
Date: 2003-09-17 17:09:25

Howard Hinnant wrote:
>
> You have to specify T if you want the assign functional to have a
> nested result_type of the correct type.  This assures that the outer
> bind returns an T&.  However I've just tested with:
>
> struct assign
> {
> template <class T, class U>
> T& operator()(T& t, const U& u) const
> {return t = u;}
> };
> ...
> bind(assign(), bind(&X::member, _1), value)(x);
>
> and it works as well.  However the resulting functional did not return
> a T&.  To achieve that one could also:
>
> T& j = bind<T&>(assign(), bind(&X::member, _1), value)(x); // returns
> T& now

The alternative is to add a result_of<assign(T, U)> specialization to tell
bind that assign()(t, u) returns T&.