defer.cpp

class Defer {
 public:
  explicit Defer(std::function<void()> func) : func_(func) {}
  ~Defer() { func_(); }

 private:
  Defer(const Defer &) = delete;
  Defer& operator=(const Defer &) = delete;
  std::function<void()> func_;
};

#define ____defer(func, line) Defer __defer_##line(func)
#define __defer(func, line) ____defer(func, line)
#define defer(func) __defer(func, __LINE__)