Question

首先让我解释一下我的层次结构：

        Person
       /     \
   Student Employee
       \     /
       Intern

每个类都有自己的output函数，用于打印其数据成员，我只需要打印Person一次。问题是Student和Employee不是抽象类，人们也会创建一个类型的对象，所以我不仅可以调用Intern级别的输出函数。

正如您将在下面的代码中看到的那样，我已经设法解决了这个问题，但我认为这很丑陋并且不是非常多态的。我已经创建了一个额外的输出函数，因此它适用于所有情况。有没有更好的方法来实现这一目标？

class Person {
    string name;
    int id;
public:
        virtual void output(ostream& out) {
        out << name << "," << id;
    }
}

学生：

class Student : virtual public Person {
    string major;
    int year;
public:
    virtual void output(ostream& out) {
        Person::output(out);
        out << "," << major << "," << year;
    }
    virtual void outputStudOnly(ostream& out) {
        out << "," << major << "," << year;
    }
};

员工：

class Employee : virtual public Person{
    string jobTitle;
public:
    virtual void output(ostream& out) {
        Person::output(out);
        out << "," << jobTitle;
    }
    virtual void outputEmpOnly(ostream& out) {
        out << "," << jobTitle;
    }
};

实习生：

class Intern : public Student, public Employee {
public:
    virtual void output(ostream& out) {
        Person::output(out);
        Student::outputStudOnly(out);
        Employee::outputEmpOnly(out);
    }
};

Answer 1

那是什么模板方法。以下是我编写此代码的方法：

class Person {
    string name;
    int id;
public:
        void output(ostream& out) {
        out << name << "," << id;
        output_impl(out);
    }
private:
       virtual void output_impl(ostream& ) {}
};

class Student : virtual public Person {
    string major;
    int year;
private:
    virtual void output_impl(ostream& out) {
        out << "," << major << "," << year;
    }

};

class Employee : virtual public Person {
    string jobTitle;
private:
    virtual void output_impl(ostream& out) {
        out << "," << jobTitle;
    }
};

class Intern : public Student, public Employee {
private:
    virtual void output_impl(ostream& out) {
        Student::output_impl(out);
        Employee::output_impl(out);
    }
};

而不是在对象上调用output。

使用Diamond of death进行C ++打印

1 个答案: