voltron model calculated fields

In the field definition of a voltron model you usually specify the field and the type as a key => val associative array. In the case that you have a calculated field the current practice is to specify field => array(Type::Calculated, 'methodNameOnRecord'). With fluent lambdas I have added a short cut:

class TimeRecord extends Voltron_Model
{
    protected $table = 'time_record';

    protected $fields = array(
        'id' => Type::Primary,
        'created' => Type::Timestamp,
        'created_hour' => Type::Calculated('created')->asDateTime->formatAs('H'));
}

The magic lies with in the created_hour type definition which can also be written as Type::Calculated(I()->created->asDateTime->formatAs('H')).

Because of the oo and fluent nature of Voltron the majority of calculated fields can be defined this way rather than requiring an actual method definition in the record class.