gistfile1.php

<?php

interface Configurable
{
    static function getOptionsBag();
}

class Form implements Configurable
{
    public function __construct($options = array())
    {
        $this->options = static::getOptionsBag()->process($options);
    }

    static public function getOptionsBag()
    {
        return OptionsBag::create()
            ->addRequiredOption('foo')
            ->addOption('bar', 'blah')
        ;
    }
}

The code is so unexplicit, when your field wiggles with 20 or something options is really bad to read getOption('a') getOption('b)' only ... and so on.

Why the static bag btw? Is there any metadata need for this? I can't really see it yet.