Odafe Ojenikoh has submitted a post he's written up showing how to create a command line PHP application with the help of the Zend Framework and it's Zend_Form elements.

Over the weekend, I was toying with the idea of interactive cli applications using readline() and Zend Form for validating input. My motivation for using Zend Form or rather Zend Form elements was to exploit the power of features such as labels, validators, filters and the prospect of reusing forms within web application code.

His example code defines a Filter for the form errors (returning them as a string) and a "Cli" class that handles the interaction with the command line. Next up is a class defining the form elements - a prompt for a color name and either of the words "thank" and "you". The Cli class transforms the form elements into prompts on the command line and lets you define validators to check their input.