Default function that just returns the passed value?

Question

As a lazy developer, I like to use this trick to specify a default function:

template 

        

Answer 1

You can just build your own identity functor:

template 
class returnIdentifyFunctor
{
  public:
     auto operator ()(  T &&i ) -> decltype( std::forward(i) )
    {
      return std::move(i);
    }
};

template >
void index(std::array &x, Function&& f = Function() )
 {
    for (unsigned int i = 0; i < Size; ++i) {
            x[i] = f(i);
  }
}