ReflectionClassを使ったファクトリ

factory.php

<?php

function factory($class, array $options = array())
{
    if (count($options) === 0) {
        return new $class();
    }

    $refClass = new \ReflectionClass($class);

    $constructor = $refClass->getConstructor();

    $arguments = array();

    if ($constructor instanceof \ReflectionMethod) {
        foreach ($constructor->getParameters() as $param) {
            $paramName = $param->getName();
            if (array_key_exists($paramName, $options)) {
                $arguments[] = $options[$paramName];
                unset($options[$paramName]);
            } else {
                $arguments[] = $param->getDefaultValue();
            }
        }
    }

    if (count($options) !== 0) {
        throw new \InvalidArgumentException(
            sprintf('Not supported parameter [%s]', implode(',', array_keys($options)))
        );
    }

    return (count($arguments) >= 1)
        ? $refClass->newInstanceArgs($arguments)
        : $refClass->newInstance();
}

$options引数のtypo発見をunset()で実装した。