<?php
class A{
    function index (){
        echo ‘我是A的index‘;
    }
}

class B{
    function index (){
        echo ‘我是B的index‘;
    }
}

class C{
    function index (){
        echo ‘我是C的index‘;
    }
}

class D{
    private static $class_name;
    public static function fatory($name){
        self::$class_name =  new $name;
        return self::$class_name;
    }
}

$e = D::fatory(‘A‘)-》;

var_dump($e);