Idiom：Scope Guard

最简单的Scope Guard

class SimplestScopeGuard {
public:
  SimplestScopeGuard(std::function<void()> func) : func_(func), dismiss_(false) {}
  ~SimplestScopeGuard() {
    if (func_ && !dismiss_)
      func_();
  }

  void Dismiss() {
    dismiss_ = true;
  }

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