我在阅读EffectiveC++(第三版)第11条后编写了这段代码。#includeusingnamespacestd;#defineMAX_COLORS20classWidget{public:Widget(intseed);~Widget();Widget&operator=(constWidget&rhs);voidToString();private:Widget&SelfAssignmentUnsafe(constWidget&rhs);Widget&SelfAssignmentSafe(constWidget&rhs);Widget&SelfAssignmentAndExc