SimpleDescriptor is a gem that makes easy to attach extra informations to a generic ruby class. Version 0.2.0 implements specific method to integrate with ActiveRecord and help you keeping DRY your model validation code.
What you get is the possibility to enforce automatically validation inherited from database definition (length of strings, numeric formats, required fields).
In addition to this you get a set of methods to easily ask to your models which validations criteria are applied, tweak them and add new ones.This way you can build views helper that are aware of your model validation and display data coherently.
SimpleDescriptor makes also easy to build standardized ways to manipulate different models that share some common characteristics.
To know more about the gem read the blog post http://assertbuggy.blogspot.com/2007/06/simple-descriptor-code-less-validate.html
or visit the rubyforge home http://simpledesc.rubyforge.org