how to limitize object in class php code example

Example: php create object

$x = (object) [
    'a' => 'test',
    'b' => 'test2',
    'c' => 'test3'
];
var_dump($x);

/*
object(stdClass)#1 (3) {
  ["a"]=>
  string(4) "test"
  ["b"]=>
  string(5) "test2"
  ["c"]=>
  string(5) "test3"
}
*/