New members of functional.hpp

From: Mark Rodgers (mark.rodgers_at_[hidden])
Date: 2000-09-06 03:30:17

I was thinking of adding something like

    template <class Arg1, class Arg2 = Arg1, class Result = Arg1>
    struct plus : std::binary_function<Arg1,Arg2,Result>
    {
        Result operator()(typename call_traits<Arg1>::param_type x,
                          typename call_traits<Arg2>::param_type y) const
        {
            return x + y;
        }
    };

    template <class Arg1, class Arg2 = Arg1, class Result = Arg1>
    struct minus : std::binary_function<Arg1,Arg2,Result>
    {
        Result operator()(typename call_traits<Arg1>::param_type x,
                          typename call_traits<Arg2>::param_type y) const
        {
            return x - y;
        }
    };

to functional.hpp.  The idea would be to allow things like

     boost::plus<Foo*,std::ptrdiff_t,Foo*>()
or   boost::minus<Foo*,std::ptrdiff_t,Foo*>()
or   boost::minus<Foo*,Foo*,std::ptrdiff_t>()

as well as the traditional

    boost::minus<int>()

Thoughts anyone?

Mark