title: PHP Builder pattern without inner classes
body: <p>I've been reading through Effective Java by Joshua Bloch. I also develop in PHP and I wanted to implement the <a href="https://stackoverflow.com/questions/5007355/builder-pattern-in-effective-java">builder pattern outlined in item 2</a>, but PHP doesn't have inner classes. Is there any way to achieve this pattern in PHP, keeping the constructor for the product private?</p>