Matthew Weier O'Phinney has put together a beginners guide to code generation with the help of the Zend_CodeGenerator component of the Zend Framework (v2):
Zend Framework has offerred a code generation component since version 1.8, when we started shipping Zend_Tool. Zend_CodeGenerator largely mimics PHP's ReflectionAPI, but does the opposite: it instead generates code. [...] ZendCodeGenerator in the ZF2 repository is largely ported from Zend Framework 1, but also includes some functionality surrounding namespace usage and imports.
He includes an overview of the different code generation classes available (like PhpBody, PhpFile, PhpProperty, etc) and a bit of code to show you how to create a skeleton class that includes namespace use, class definition and the addition of a "get" method. He also offers some "tips" and "gotchas" to watch out for your first time around like the helpful automagic getter and setter handling.