如何在php父类中使用单例和静态后期绑定toghter

Question

I am trying to create a father class like:

class CommonModel extends \Common\Model\CommonModel {

protected static  $_instance = null; //singleton
/**
 * singleton
 * @return null|static
 * @Date 2017/4/7 14:06
 */
public static function instance(){
    if(!isset(self::$_instance)){
        self::$_instance = new static();
    }
    return self::$_instance;
}

UserModel and UserThirdModel implements the CommonModel

when I create $user = UserModel::instance(); //an user instance is created

$userThird = UserThirdModel::instance();// userModel retured.

I see the problem comes from "if(!isset(self::$_instance)){" my question is how to create different instance based on different model

Thanks

Answer 1

You could turn $_instance into an array of instances by class name using get_called_class() http://php.net/manual/en/function.get-called-class.php

First change

protected static  $_instance = array(); //singleton array

and then use self::$_instance[get_called_class()] such as...

public static function instance(){
    if(!isset(self::$_instance[get_called_class()])){
        self::$_instance[get_called_class()] = new static();
    }
    return self::$_instance[get_called_class()];
}