构造函数之前调用的静态对象和成员方法 [英] static object and member method called before constructor

问题描述

我有两个类A和B，因此A具有一个静态B实例作为其成员。 B有一个函数Show（），这是我的类A：

I have two classes A and B such that A has a static B instance as its member. B has a function Show() and here is my class A:

class A
{
  A()
  {
    _b.Show();
  }
private:

  static B _b; 
};

，后续代码为

A a;
B A::_b;

int main()
{
}

a和_b的顺序，因此在构造B之前调用B :: Show（）。但是，这到底是如何工作的，即如何对尚未构造的对象进行调用？

Now B::Show() called before B is constructed due to the sequence in which I have defined a and _b. But how does this work exactly i.e. how is it possible to make calls on an object that is still not constructed ?

推荐答案

可能是未定义的行为（在这种情况下，因为您正在访问未初始化的对象），因为 a 在 A :: _ b 。

It's not possible, it's undefined behavior (in this case, because you're accessing an uninitialized object) because a is initialized before A::_b.

查找静态初始化顺序失败。您不会收到任何错误，因为在这种情况下，有99％的情况会发生，这很容易诊断。

Look up static initialization order fiasco. You don't get an error because 99% of the times this happens, it's not easily diagnosable.

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