Go の defer っぽいものを C++ でやってみる遊び

defer.cpp

#include <functional>

class defer_t {
private:
  std::function<void(void)> f;
public:
  defer_t(std::function<void(void)> f);
  ~defer_t(void);
};

defer_t::defer_t(std::function<void(void)> f) : f(f) {}
defer_t::~defer_t(void) { f(); }

#define defer_helper2(line) defer_tmp ## line
#define defer_helper(line) defer_helper2(line)
#define defer(x) auto defer_helper(__LINE__) = defer_t([&](void){x});


/*
  https://qiita.com/joji/items/b933b03bc30b26848d19
  を元にした使用例
*/

#include <iostream>

void test(void) {
  defer( std::cout << "test world" << std::endl; )
}

void test2(){
  defer( std::cout << "test2 world" << std::endl; )
}

int main(void) {
  defer( std::cout << "world1" << std::endl; )
  defer( std::cout << "world2" << std::endl; )
  test();
  test2();
  std::cout << "world" << std::endl;

  return 0;
}