Posted by steveoliver on November 11, 2011 at 9:06pm
The Form Stepper module is an example of multistep forms in Drupal using variable functions, based largely on the work of Ben Jeavons.
Using the (dependency) AHAH Helper module by Wim Leers, it supports #ahah functionality on each step. And each step determines the next step, either in the _form, _validate, or _submit callbacks.
For more information on the background of this module, one specific use case, and the future (requirements) of this approach to multi-step forms in Drupal, see http://drupalsteve.com/node/54. The module is currently written for D6, but can be easily adapted to D7.