【PHP】不変オブジェクト

immutable.php

<?php

namespace Acme;

class Immutable
{
	protected $some = "some";

	public function getSome()
	{
		return $this->some;

	}

	public function withSome($some)
	{
		$clone = clone $this;
		$clone->some = $some;
		return $clone;

	}
	
	public function __set($name, $value)
	{
		throw new \InvalidArgumentException();

	}

}