Method "CI_Validation::set_fields()" for the new version class "CI_Form_validation" of the latest version CodeIgniter

[eluser]pierrehs[/eluser]
Hello,
I'm trying to migrate my old site with the old version of CodeIgniter to the latest version (2.1).

But with the validation class, I would like to know what the new method similar to old class "CI_Validation::set_fields()" for the new class "CI_Form_validation"
Tthank you