Does a no-op "do nothing" function object exist in C++(0x)?

Question

I realize this is a ludicrous question for something that takes less than 2 seconds to implement. But I vaguely remember reading that one was introduced with the new standard.

I grep'ed VC10's headers and came up with nothing. Can you help? It's bugging me! :)

edit: On second thought, the new functor I was remembering was probably the unrelated std::default_deleter.

Answer 1

You could always write a no-op lambda: []{}

Answer 2

You was probably thinking about the identity function (std::identity and apparently it's removed in the current draft) that is not the same thing though.

Answer 3

How about this?

// Return a noop function 
template <typename T>
struct noop
{
  T return_val;

  noop (T retval = T ())
       :  return_val (retval)
  {
  }

  T
  operator (...)
  {
    return return_val;
  }
};

template <>
struct noop<void>
{
  void
  operator (...)
  {
  }
};

This should work for just about any use.