это магические методы ООП php

class Test{

public $_fields = array();

public $_composites= array(

    'Alias' => array(

        //addition

    ),

);

public function __call(){}

public function __get($varname){

    return $this->_cmposites[$varname]?$this->_cmposites[$varname]:$this->_fields[$varname];

}

public function __set($varname){

    

    //Some....logic for add relationship object

}

}

$test = new Test();

$test->Alias = $object;