C++: destroy/destroy_at/destroy_n

개요

• destroy
  • 범위의 객체를 파괴
• destroy_at
  • 객체를 파괴
• destroy_n
  • 범위의 시작부터 n개의 객체를 파괴

예제

• 코드

    #include <iostream>
    #include <memory>

    using namespace std;

    class Test {
    	private:
    		// int i;

    	public:
    		int i;

    		Test(int i) : i(i) {}
    		~Test() { cout << "~Test() : " << this->i << endl; }
    };

    void destroy_test() {
    	cout << __func__ << " start" << endl;

    	constexpr int size = 3;

    	unsigned char pool[sizeof(Test) * size];

    	for (int i = 0; i < size; ++i) {
    		new (pool + (sizeof(Test) * i)) Test(i);
    	}

    	auto ptr = launder(reinterpret_cast<Test *>(pool));

    	destroy(ptr, ptr + size);

    	cout << __func__ << " end" << endl;
    }

    void destroy_at_test() {
    	cout << __func__ << " start" << endl;

    	constexpr int size = 3;

    	unsigned char pool[sizeof(Test) * size];

    	for (int i = 0; i < size; ++i) {
    		new (pool + (sizeof(Test) * i)) Test(i);
    	}

    	auto ptr = launder(reinterpret_cast<Test *>(pool));

    	for (int i = 0; i < size; ++i) {
    		destroy_at(ptr + i);
    	}

    	cout << __func__ << " end" << endl;
    }

    void destroy_n_test() {
    	cout << __func__ << " start" << endl;

    	constexpr int size = 3;

    	unsigned char pool[sizeof(Test) * size];

    	for (int i = 0; i < size; ++i) {
    		new (pool + (sizeof(Test) * i)) Test(i);
    	}

    	auto ptr = launder(reinterpret_cast<Test *>(pool));

    	destroy_n(ptr, size);

    	cout << __func__ << " end" << endl;
    }

    int main() {
    	destroy_test();

    	cout << endl;

    	destroy_at_test();

    	cout << endl;

    	destroy_n_test();

    	return 0;
    }

• 실행 결과

    destroy_test start
    ~Test() : 0
    ~Test() : 1
    ~Test() : 2
    destroy_test end

    destroy_at_test start
    ~Test() : 0
    ~Test() : 1
    ~Test() : 2
    destroy_at_test end

    destroy_n_test start
    ~Test() : 0
    ~Test() : 1
    ~Test() : 2
    destroy_n_test end