[boost] New members of functional.hpp

From: jsiek_at_[hidden]
Date: 2000-09-06 09:15:10

Yes, these are very much needed. All the binary functions
should have three template paramters.

Mark Rodgers writes:
 > 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
 > 
 > 
 > 
 > 
 > 
 >