custom validations only if all attributes are valid

Guys,

there are people who see a value in validation dependency and who don’t.

I want to add this to Rails core and ready to make a pull request.
But I need some help about the name of the method (validate_after, validate_with_dependency, validate_further, etc.) and usage of this approach.

I posted earlier what I use on my project. I think that the interface of this method should be the same with validate method (:on, :if/:unless).