<?php

/**

 * Created by PhpStorm.

 * User: andy

 * Date: 16-11-23

 * Time: 下午7:57

 */

interface User

{

    function getName();

}

interface Teacher

{

    function getWorkYear();

}

class Student implements User

{

    private $name = 'lisi';

    function getName()

    {

        // TODO: Implement getName() method.

        echo 'Student name is ' . $this->name . '<br />';

    }

}

class GraduateTeacher implements Teacher

{

    private $work_year = 2;

    function getWorkYear()

    {

        // TODO: Implement getWorkYear() method.

        echo 'Teacher work year is ' . $this->work_year . '<br />';

    }

}

class GraduateStudent extends Student implements Teacher

{

    private $teacher;

    public function __construct()

    {

        $this->teacher = new GraduateTeacher();

    }

    function getWorkYear()

    {

        $this->teacher->getWorkYear();

    }

}

class Test

{

    static function getName(User $student)

    {

        $student->getName();

    }

    //当Teacher改成GraduateTeacher，到后面代码行的“Test::getWorkYear($lisi);”就会报错

    static function getWorkYear(Teacher $teacher)

    {

        $teacher->getWorkYear();

    }

}

$lisi = new GraduateStudent();

$lisi->getName();

$lisi->getWorkYear();

echo '<hr />';

Test::getName($lisi);

Test::getWorkYear($lisi); //这里不会报错，因为$lisi所属的类GraduateStudent，实现了Teacher的接口，相当于Teacher身份