I have a class that keeps data stores/access data by using words.separated.by.dots keys and it behaves like the following:

    $object = new MyArray()
    $object->setParam('user.name','marcelo');
    $object->setParam('user.email','[email protected]');

    $object->getParams();

    /*
    array(
        'user' => array(
            'name' => 'marcelo',
            'email' => '[email protected]'
        )
    );
    */

It is working, but the method unsetParam() was horribly implemented. That happened because i didn't know how to achieve that without eval() function. Although it is working, I found that it was a really challenging algorithm and that you might find fun trying to achieve that without eval().

class MyArray {
   /**
     * @param string $key
     * @return Mura_Session_Abstract 
     */
    public function unsetParam($key)
    {
        $params = $this->getParams();
        $tmp = $params;
        $keys = explode('.', $key);

        foreach ($keys as $key) {
            if (!isset($tmp[$key])) {
                return $this;
            }
            $tmp = $tmp[$key];
        }

        // bad code!
        $eval = "unset(\$params['" . implode("']['", $keys) . "']);";
        eval($eval);

        $this->setParams($params);
        return $this;
    }
}

The test method:

public function testCanUnsetNestedParam()
{
    $params = array(
        '1' => array(
            '1' => array(
                '1' => array(
                    '1' => 'one',
                    '2' => 'two',
                    '3' => 'three',
                ),
                '2' => array(
                    '1' => 'one',
                    '2' => 'two',
                    '3' => 'three',
                ),
            )
        ),
        '2' => 'something'
    );

    $session = $this->newSession();
    $session->setParams($params);

    unset($params['1']['1']['1']);
    $session->unsetParam('1.1.1');

    $this->assertEquals($params, $session->getParams());
    $this->assertEquals($params['1']['1']['2'], $session->getParam('1.1.2'));
}