Re: [boost] [range] treating N-ary function with N-1 default args as unary

Subject: Re: [boost] [range] treating N-ary function with N-1 default args as unary
From: Mathias Gaunard (mathias.gaunard_at_[hidden])
Date: 2012-06-30 22:42:44

On 01/07/2012 01:18, Vicente J. Botet Escriba wrote:

> Could a lambda help on this context?
>
> int main()
> {
>      int A[5];
>      A | boost::adaptors::transformed([](int a){ return foo(a);});
> }

The OP already pointed this one out. It's not satisfying because it 
requires specifying the type of the first argument.

Something you could do in C++11

int main()
{
      struct foo_type
      {
           template<class Sig>
           struct result;

           template<class This, class A0>
           struct result<This(A0)>
           {
                typedef decltype(foo(declval<A0>())) type;
           };

           template<class A0>
           typename result<foo_(A0&&)>::type operator()(A0&& a0) const
           {
                return foo(forward<A0>(a0));
           }
      };
      foo_type foo_;
      int A[5];
      A | boost::adaptors::transformed(foo_);
}

The functor could be generated by a macro that would just take the 
function name and the number of arguments.