returning functions in c++

.gitignore

/a.out

test_return_function.cpp

// http://stackoverflow.com/questions/4726768/returning-functions-in-c
// g++ -std=c++0x test_return_function.cpp && ./a.out
#include <functional>
#include <iostream>

namespace {
  std::function<int()>
  make_counter(int start=0){ // closure
    return [start]() mutable { return start++; };
  }

  typedef int (*identity_t)(int);

  identity_t 
  identity() { // stateless lambda
    return [](int x) { return x; };
  }
}
int main() {
  using namespace std;

  auto count = make_counter(4);
  auto count2 = make_counter();
  cout << count() << " ";
  cout << count2() << " ";
  cout << count() << " ";
  cout << count() << " ";
  cout << count2() << endl;

  auto same = identity();
  cout << same(4) << " "
       << same(0) << " "
       << same(5) << " "
       << same(6) << " "
       << same(1) << endl;

  return 0;
}