c++中模拟swift中的defer

class _Defer
{
public:
    ~_Defer()
    {
        closure();
    }
    std::function<void()> closure;
};

#define _Defer_CONCATENATE_IMPL(s1, s2) s1##s2
#define _Defer_CONCATENATE(s1, s2) _Defer_CONCATENATE_IMPL(s1, s2)
#define defer _Defer _Defer_CONCATENATE(__Defer, __LINE__); _Defer_CONCATENATE(__Defer, __LINE__).closure = [&]()

class Test
{
public:
    ~Test()
    {
        std::cout << "destructor" << std::endl;
    }
};

void test()
{
    Test* a = new Test();
    defer {
        delete a;
    };
    std::cout << 123456 << std::endl;
}

输出：

123456

destructor