c++ - 从成员初始化程序列表中调用基本方法

Question

从成员初始化程序列表中调用非虚拟基本方法是否安全？和虚拟的？

Answer 1

在初始化所有基础之前，调用任何成员函数(虚拟的或非虚拟的)是不安全的。下面是标准([class.base.init]§16)中给出的示例:

class A {
public:
  A(int);
};

class B : public A {
  int j;
public:
  int f();
  B() : A(f()),     // undefined behavior: calls member function but base A not yet initialized
  j(f()) { }        // well-defined: bases are all initialized
};

class C {
public:
  C(int);
};

class D : public B, C {
  int i;
public:
  D() : C(f()),     // undefined behavior: calls member function but base C not yet initialized
  i(f()) { }        // well-defined: bases are all initialized
};

还有更多的 subtle cases。