c++ - 继承和初始化顺序

Question

考虑

 class A
   {
   };

 class B
   {
     B(A * in);
   };

 class C : public A
  {
    B b;
   public:
   C():b(this){}
  };

C 中的构造函数安全吗？ A 的成员是否已经可用(并已构建)？

Answer 1

是的。在执行构造函数的其余部分之前构造所有基类。

例如，来自 Stroustrup C++ 2011 一书:

17.2.3 Base and Member Destructors
Constructors and destructors interact correctly with class hierarchies (§3.2.4, Chapter 20). A constructor
builds a class object ‘‘from the bottom up’’:
[1] first, the constructor invokes its base class constructors,
[2] then, it invokes the member constructors, and
[3] finally, it executes its own body.
A destructor ‘‘tears down’’ an object in the reverse order:
[1] first, the destructor executes its own body,
[2] then, it invokes its member destructors, and
[3] finally, it inv okes its base class destructors.