Question

考虑

 class A
   {
   };

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

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

C中的构造函数是否安全？ A的成员是否已经可用（并已构建）？

Answer 1

是肯定的。在执行构造函数的其余部分之前构造所有Base类。

例如，来自Stroustrup C ++ 2011书籍：

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.

继承和初始化的顺序

1 个答案: