是否可以前向声明一个嵌套类,并将其用作外部类的具体(而不是指针/引用)数据成员的类型?
即:
class Outer;
class Outer::MaybeThisWay // Error: Outer is undefined
{
};
class Outer
{
MaybeThisWay x;
class MaybeThatOtherWay;
MaybeThatOtherWay y; // Error: MaybeThatOtherWay is undefined
};