学习笔记：动态分派和静态分派

来源：互联网发布：快速排序算法 php 编辑：程序博客网时间：2024/05/23 17:56
#include "stdafx.h"#include <iostream>struct CEmployee;struct CProgrammer;struct CJuniorProgrammer;struct CVeteranProgrammer;struct CManager;struct CCEO;class IVisitor{public:    virtual void Visit(CEmployee* p) = 0;    virtual void Visit(CProgrammer* p) = 0;    virtual void Visit(CJuniorProgrammer* p) = 0;    virtual void Visit(CVeteranProgrammer* p) = 0;    virtual void Visit(CManager* p) = 0;    virtual void Visit(CCEO* p) = 0;};#define FIRST_DISPATCH \virtual void Accept(IVisitor *v){ v->Visit(this);}#define SECOND_DISPATCH \    virtual void Visit(CEmployee* p         ) {visit_helper(p);} \    virtual void Visit(CProgrammer* p       ) {visit_helper(p);} \    virtual void Visit(CJuniorProgrammer* p ) {visit_helper(p);} \    virtual void Visit(CVeteranProgrammer* p) {visit_helper(p);} \    virtual void Visit(CManager* p          ) {visit_helper(p);} \    virtual void Visit(CCEO* p              ) {visit_helper(p);} \struct CEmployee{  FIRST_DISPATCH};struct CProgrammer : public CEmployee{  FIRST_DISPATCH};struct CJuniorProgrammer : public CProgrammer{ FIRST_DISPATCH};struct CVeteranProgrammer : public CProgrammer{  FIRST_DISPATCH};struct CManager : public CEmployee{  FIRST_DISPATCH};struct CCEO : public CEmployee{  FIRST_DISPATCH};class SalaryVisitor:public IVisitor{public:    //通过宏定义，帮助实现更便利的书写    SECOND_DISPATCH    //help函数的作用是：避免对每个子类都写代码    void visit_helper(CEmployee* p){        std::cout << "默认的算法，相当于default或者else" << std::endl;    }    void visit_helper(CProgrammer* p){        std::cout << "程序员基类。对一小类做“特殊处理”）" << std::endl;    }    void visit_helper(CCEO* p){        std::cout << "对具体的某个类做“特殊处理”）" << std::endl;    }};int main() {    IVisitor* pv = new SalaryVisitor();    CEmployee* pe = new CVeteranProgrammer();    pe->Accept(pv);    return 0;}
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