单例模式

/**
 * @author xiaojiang
 * 方式1
 */
class father{
    static $models = [];
    static public function getInstance(){
        $name =  get_called_class();
        if( !isset( self::$models[$name] ) ){
            self::$models[$name] = new $name();
        }
        return self::$models[$name];
    }
    
    public function m1(){
        echo "fm1";
    }
    public function m2(){
        echo "fm2";
    }
}
class child extends father{
    public function m1(){
        echo 'cm1';
    }
}
father::getInstance()->m1();
child::getInstance()->m1();

/**
 * 方式2
 */
 class base{

    static protected  $ins = [];
    
    static public function getInstance(){
        $cName = get_called_class();
        if( !isset(static::$ins[$cName]) ){
            static::$ins[$cName] = new $cName;
        }
        return static::$ins[$cName];
    }
    
    public function m1(){
        return "base m1";
    }
    
    public function m2(){
        return "base m2";
    }
    
}

class cbase extends base{
    
    //static public $ins = null;
    static public function getInstance(){
        return parent::getInstance();
    }
    
    public function m1(){
        return "cbase m1<br>";
    }
    
}


echo base::getInstance()->m1()."<br>";

echo cbase::getInstance()->m1();