初始化引用 - 警告C4355：'this'：用于基本成员初始化程序列表 [英] Initialize a reference - warning C4355: 'this' : used in base member initializer list

问题描述

class A;

class B {
public:
    B(A& a) : a(a) {}
private:
    A& a;
};

/* Method 1 */
/* warning C4355: 'this' : used in base member initializer list */
/*
class A {
public:
    A() : b(*this) {}

private:
    B b;
};
*/

/* Method 2 */
/* But I need to manually perform memory dellocation. */
class A {
public:
    A() { b = new B(*this); }
    ~A() { delete b; }

private:
    B* b;
};

int main() {
}

目前，我尝试初始化B中的引用，我使用方法1.但是，方法1将标记我的警告，这是可以理解的。

Currently, when I try to initialize the reference in B, I am using Method 1. However, Method 1 will flag me warning which is understandable.

因此，我必须回退使用方法2，通过使用动态内存分配。

Hence, I have to fall back using Method 2, by using dynamic memory allocation.

有没有更好的方式，我可以使用，而不需要手动内存分配/ dellocation（确定，我知道智能指针）

Is there any better way I can use, without the need of manual memory allocation/ dellocation (OK. I know smart pointer)?

我更喜欢方法1，只是我对警告不舒服。

I prefer Method 1, just that I am not comfortable with the warning.

推荐答案

注意这是一个警告（所以这是危险的，不是非法的）。

Note this is a warning (so it is dangerous not illegal).

编译器担心的是，对象尚未完全初始化。因此，如果指针在B类构造函数中使用，你将处于未定义的行为。

What the compiler is worried about is that you are passing a pointer for an object that has not been fully initialized. Thus if the pointer is used in the B class constructor you are in undefined behavior.

所以如果你使用这个，你可以做的唯一的事情是将指针成员变量（引用或指针）。 但是注意注意对变量的分配，因为你可以调用一个隐式转换（我不知道这是否实际上是一个问题，但RTTI不可用，直到对象完全形成）。

So if you do use this the only thing you can do is assign the pointer to a member variable (reference or pointer). But note be careful of the assignment to a variable as you may invoke an implicit cast (I am not sure if that is actually a problem but the RTTI is not available until the object is fully formed).

您通过存储引用要实现什么？

What are you trying to achieve by storing the reference?

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