Prevent unnecessary copies of C++ functor objects

Question

I have a class which accumulates information about a set of objects, and can act as either a functor or an output iterator. This allows me to do things like:

Answer 1

If you have a recent compiler (At least Visual Studio 2008 SP1 or GCC 4.4 I think) you can use std::ref/std::cref

#include 
#include 
#include  // for std::cref
#include 
#include 

template 
class SuperHeavyFunctor 
{
    std::vector v500mo;
    //ban copy
    SuperHeavyFunctor(const SuperHeavyFunctor&);
    SuperHeavyFunctor& operator=(const SuperHeavyFunctor&);
public:
    SuperHeavyFunctor():v500mo(500*1024*1024){}
    void operator()(const T& t) const { std::cout << t << std::endl; }
};

int main()
{
    std::vector v; v.push_back("Hello"); v.push_back("world");
    std::for_each(v.begin(), v.end(), std::cref(SuperHeavyFunctor()));
    return 0;
}

Edit : Actually, the MSVC10's implementation of reference_wrapper don't seem to known how to deduce the return type of function object operator(). I had to derive SuperHeavyFunctor from std::unary_function to make it work.