If you would like to extend the framework, you can write your own class that extends the framework classes.

For instance, you might want to extend the DooValidator. You can write your own validator class in protected/class

Doo::loadHelper('DooValidator');

classs MyValidator extends DooValidator{
     //..??your extended code..
}

And then you can use your extended class in controller:

Doo::loadClass('MyValidator');

Read more tips & tricks at the forum

good work