Abstract ArrayOf Class

ArrayOf.php

<?php

abstract class ArrayOf implements ArrayAccess, Iterator
{
	protected $type = null;

	protected $data = [];

	protected $index = 0;

	public function __construct()
	{
		if (is_null($this->type)) {
			throw new Exception('Extending classes must specify a type.');
		}
	}

	public function offsetExists($offset)
	{
		return isset($this->data[$offset]);
	}

	public function offsetGet($offset)
	{
		return $this->data[$offset];
	}

	public function offsetSet($offset, $value)
	{
		if ($value instanceof $this->type) {
			$this->data[$offset] = $value;
		} else {
			$type = is_object($value) ? get_class($value) : gettype($value);

			throw new UnexpectedValueException(
				sprintf('Value must be of type %s, %s given.', $this->type, $type)
			);
		}
	}

	public function offsetUnset($offset)
	{
		unset($this->data[$offset]);
	}

	public function current()
	{
		return $this->data[$this->index];
	}

	public function next()
	{
		++$this->index;
	}

	public function key()
	{
		return $this->index;
	}

	public function valid()
	{
		return isset($this->data[$this->index]);
	}

	public function rewind()
	{
		$this->index = 0;
	}
}

class ArrayOfFoo extends ArrayOf
{
	protected $type = 'Foo';
}

class Foo
{
	public function doSomething($i)
	{
		echo $i . PHP_EOL;
	}
}

$fooArray = new ArrayOfFoo;

for ($i=0; $i<100; $i++) {
	$fooArray[$i] = new Foo;
}

function needsFooArray(ArrayOfFoo $fooArray) {
	foreach ($fooArray as $i => $foo) {
		$foo->doSomething($i);
	}
}

needsFooArray($fooArray);