在初始化列表中使用“this”指针是否安全？(Is it safe to use the “this” pointer in an initialization list?)

 我有两个父子关系的类（ Parent类“has-a” Child类），而Child类有一个指针返回到Parent 。 在构建孩子时初始化父指针是很好的，如下所示： 
 
class Child
{
public:
 Child (Parent* parnet_ptr_) : parent_ptr(parent_ptr_) {};

private:
 Parent* parent_ptr;
};

class Parent
{
public:
    Parent() : child(this) {};

private:
    Child child;
}
 
 现在，我知道人们建议不要在初始化列表中使用this ，而C ++常见问题解答说我会得到一个编译器警告（BTW，在VS2010，我没有得到警告），但我真的很喜欢这个更好，然后调用一些设置在Parent构造函数中的函数。 我的问题是： 
 
 
 
 当父对象被创建时，父指针是否定义良好？ 
 
 
 如果是这样，为什么要像上面那样使用它是坏的做法？ 
 
 
 谢谢， 
 
 波阿斯 
 
 编辑：感谢Timbo，确实是重复的 （嗯，我甚至选择了相同的类名）。 所以我们可以获得一些附加值：引用如何？ 执行以下操作是否可能/安全？ ： 
 
class Child
{
public:
 Child (Parent& parnet_ptr_) : parent_ptr(parent_ptr_) {};

private:
 Parent* parent_ptr;
};

class Parent
{
public:
    Parent() : child(*this) {};

private:
    Child child;
}

I have two classes with a parent-child relationship (the Parent class "has-a" Child class), and the Child class has a pointer back to the Parent. It would be nice to initialize the parent pointer upon construction of the child, as follows:
 
class Child;
class Parent;

class Child
{
public:
 Child (Parent* parent_ptr_) : parent_ptr(parent_ptr_) {};

private:
 Parent* parent_ptr;
};

class Parent
{
public:
    Parent() : child(this) {};

private:
    Child child;
}
 
Now, I know people recommend not using this in initialization list, and C++ FAQ says I'm gonna get a compiler warning (BTW, on VS2010, I don't get a warning), but I really like this better then calling some set function in Parent's constructor. My questions are:
 
 
 
Is the parent this pointer well-defined when the Child object is being created?
 
 
If so, why is it considered bad practice to use it as above?
 
 
Thanks,
 
Boaz
 
EDIT: Thanks Timbo, it is indeed a duplicate (huh, I even chose the same class names). So lets get some added value: how about references? Is it possible / safe to do the following? :
 
class Child
{
public:
 Child (Parent& parnet_ptr_) : parent_ptr(parent_ptr_) {};

private:
 Parent* parent_ptr;
};

class Parent
{
public:
    Parent() : child(*this) {};

private:
    Child child;
}

原文：https://stackoverflow.com/questions/5058349