A Simple ParameterBag

ParameterBag.php

<?php

class ParameterBag implements \IteratorAggregate, \Countable
{
    /**
     * @var array
     */
    private $parameters;

    private $froozen = false;

    /**
     * @param array $parameters
     */
    public function __construct($parameters = array())
    {
        $this->setParameters($parameters);
    }

    public function set($id, $value)
    {
        if ($this->isFroozen()) {
            throw new \OverflowException('You cannot change a froozen parameterbag');
        }

        $this->parameters[$id] = $value;
    }

    public function get($id)
    {
        if (!$this->has($id)) {
            throw new \OutOfBoundsException(sprintf('The parameter "%s" is not found', $id));
        }

        return $this->parameters[$id];
    }

    public function has($id)
    {
        return array_key_exists($id, $this->getParameters());
    }

    /**
     * @return array
     */
    public function getParameters()
    {
        return $this->parameters;
    }

    public function freeze()
    {
        if ($this->isFroozen()) {
            throw new \BadMethodCallException('The parameterbag is already froozen');
        }

        $this->froozen = true;
    }

    public function isFroozen()
    {
        return $this->froozen;
    }

    /**
     * {@inheritDoc}
     */
    public function getIterator()
    {
        return new \ArrayIterator($this->getParameters());
    }

    /**
     * {@inheritDoc}
     */
    public function count()
    {
        return count($this->getParameters());
    }

    private function setParameters(array $parameters)
    {
        $this->parameters = $parameters;
    }
}

ParameterBagTest.php

<?php

require_once 'ParameterBag.php';

class ParameterBagTest extends \PHPUnit_Framework_TestCase
{
    public function testNormalBehaviour()
    {
        $pb = new ParameterBag();
        $pb->set('foo', 'lorem');
        $pb->set('bar', 'ipsum');

        $this->assertEquals('lorem', $pb->get('foo'));

        $pb->set('baz', 'dolor');

        $this->assertEquals('ipsum', $pb->get('bar'));
        $this->assertEquals('dolor', $pb->get('baz'));
    }

    public function testFreezing()
    {
        $pb = new ParameterBag();
        $pb->set('foo', 'lorem');
        $pb->freeze();

        $this->assertTrue($pb->isFroozen());

        $this->assertEquals('lorem', $pb->get('foo'));
    }

    /**
     * @expectedException OverflowException
     */
    public function testCannotChangeAFroozenBag()
    {
        $pb = new ParameterBag();
        $pb->freeze();

        $pb->set('foo', 'lorem');
    }

    public function testCountParameters()
    {
        $pb = new ParameterBag();
        $pb->set('foo', 'lorem');
        $pb->set('bar', 'ipsum');
        $pb->set('baz', 'dolor');

        $this->assertEquals(3, count($pb));
    }

    public function testIterator()
    {
        $pb = new ParameterBag();
        $pb->set('foo', 'lorem');
        $pb->set('bar', 'ipsum');
        $pb->set('baz', 'dolor');
        $expected = array('lorem', 'ipsum', 'dolor');

        foreach ($pb as $p) {
            $this->assertContains($p, $expected);
        }
    }
    
    public function testFilter()
    {
        $pb = new ParameterBag();
        $pb->set('foo', 'lorem');
        $pb->set('bar', 'ipsum');
        $pb->set('baz', 'dolor');

        $filter = new \CallbackFilterIterator($pb->getIterator(), function ($current, $key) {
            return 'ba' === substr($key, 0, 2);
        });

        $this->assertCount(2, $filter);
        $this->assertFalse($pb->has('lorem'));
    }

}