c++ - 链成员初始值设定项

Question

是否可以在“类初始化程序”中引用类成员？

示例:

struct Example
{
  std::string a = "Hello";
  std::string b = a + "World";
};

它似乎可以工作(编译并运行)，但是可以吗？

Answer 1

默认初始值设定项允许这样做 since C++11 。向下滚动到“用法”部分并查看第一个示例。我在这里复制了解释和示例以方便引用:

The name of a non-static data member or a non-static member function can only appear in the following three situations:

1. As a part of class member access expression, in which the class either has this member or is derived from a class that has this member, including the implicit this-> member access expressions that appear when a non-static member name is used in any of the contexts where this is allowed (inside member function bodies, in member initializer lists, in the in-class default member initializers).

struct S
{
    int m;
    int n;
    int x = m;            // OK: implicit this-> allowed in default initializers (C++11)
    S(int i) : m(i), n(m) // OK: implicit this-> allowed in member initializer lists
    {
        this->f();        // explicit member access expression
        f();              // implicit this-> allowed in member function bodies
    }
    void f();
};