访问者模式

访问者模式 当你想要为一个对象的组合增加新的能力，且封装并不重要时，就使用访问者模式（Visitor Pattern）

#include <iostream>
#include <list>
#include <string>

using namespace std;

class CPerson;
class CStudent;
class CTeacher;

class CVisitor;
class CPrinter;


class CPerson {
protected:
    string name;
    int gender;
    CPerson() {}
public:
    virtual void Accept(CVisitor &) {}
    void SetName(const string& Name) {
        name = Name;
    }
    string GetName() const {
        return name;
    }
    void SetGender(const int &Gender) {
        gender = Gender;
    }
    int GetGender() const {
        return gender;
    }
};

class CVisitor {
public:
    virtual void Visit(CStudent &) = 0;
    virtual void Visit(CTeacher &) = 0;
};

class CStudent : public CPerson {
private:
    int grade;
public:
    CStudent(string Name,int Gender,int Grade) {
        name = Name;
        gender = Gender;
        grade = Grade;
    }
public:
    virtual void Accept(CVisitor &printer) {
        printer.Visit(*this);
    }
    void SetGrade(int Grade) {
        grade = Grade;
    }
    int GetGrade() const {
        return grade;
    }
};

class CTeacher:public CPerson {
private:
    int service_time;
public:
    CTeacher(string Name, int Grade, int ServiceTime) {
        name = Name;
        gender = Grade;
        service_time = ServiceTime;
    }
    virtual void Accept(CVisitor& printer) {
        printer.Visit(*this);
    }
    void SetServiceTime(int ServiceTime) {
        service_time = ServiceTime;
    }
    int GetServiceTime() const {
        return service_time;
    }
};

class CPrinter: public CVisitor {
public:
    void Visit(CStudent &s) {
        cout << "student:" <<endl;
        cout << "\t Name:" <<s.GetName() <<endl;
        cout << "\t Gender:" <<
            (s.GetGender() ? "male" : "female") << endl;
        cout << "\t Grade:" <<s.GetGrade() <<endl;
    }

    void Visit(CTeacher &t) {
        cout << "Teacher:" <<endl;
        cout << "\t Name:" <<t.GetName() <<endl;
        cout << "\t Gender:" <<
            (t.GetGender() ? "male" : "female") << endl;
        cout << "\t Service Time:" << t.GetServiceTime() << endl;
    }
};

class Organization {
private:
    typedef list<CPerson*> CMemberList;
    CMemberList member_list;

public:
    void Add(CPerson* person) {
        member_list.push_back(person);
    }
    void PrintMembers(CPrinter &printer) {
        CMemberList::iterator itr = member_list.begin();
        for(; itr != member_list.end(); ++itr) {
            (*itr)->Accept(printer);
        }
    }
    ~Organization() {
        CMemberList::iterator itr = member_list.begin();
        for(; itr != member_list.end(); ++itr) {
            delete *itr;
        }
    }
};


int main(int argc, char **argv)
{
    Organization Planting;
    Planting.Add(new CTeacher("Johnny",1,10));
    Planting.Add(new CStudent("Catherine",0,1));
    Planting.Add(new CStudent("Peter",1,2));

    CPrinter printer;
    Planting.PrintMembers(printer);

    return 0;
}