Yes, also see github.com/dwightwatson/validating for a more extensive example :)

I dont like to use an attribute to store validation rules. What if you want different validation rules for creating and updating ? What if you want to append the id of the instance to an unique rule so the updating works ? I prefer a getRules method which returns an array of rules.

Anyway there is so many real case example not suited to model validation that i prefer to use validation classes.

In our case our needs are met by this. We build our own custom validators where needed and the "rules are the rules". It works for us™.