<?php
class work{
  function polymorphic($obj){
    //檢查是否引用類型(obj是否繼承animal類)
    if($obj instanceof animal){
      $obj -> fun();
    }
    else{
      echo "no function";
    }
  }
  //如果需要指定類 (指定cat類，包含cat子類)
  function bose(cat $obj){
    $obj->fun();
  }
}
//抽象類
 abstract class animal{
  abstract function fun();
}
//cat貓類
class cat extends animal{
  function fun(){
    echo "cat say miaomiao...";
  }
}
//dog狗類
class dog extends animal{
  function fun(){
    echo "dog say wangwang...";
  }
}
class mouse extends cat{
}
//先new一個(gè)work類
$new_work = new work();
//然后通過new_work對(duì)象 調(diào)用 polymorphic 方法,傳入不同的類實(shí)現(xiàn) 父類引用指向子類對(duì)象；接口引用指向?qū)崿F(xiàn)接口的類對(duì)象(多態(tài))。
$new_work->polymorphic(new cat());
echo '<br/>';
$new_work->polymorphic(new dog());
echo '<br/>';
//指定類方式仿java
$new_work->bose(new cat());
echo '<br/>';
//如果傳輸其他類，或者未繼承cat類則會(huì)報(bào)錯(cuò)
//$new_work->bose(new dog());
echo '<br />';
//這也不會(huì)報(bào)錯(cuò)
$new_work->bose(new mouse());

cat say miaomiao...
dog say wangwang...
cat say miaomiao...

cat say miaomiao...