Trans wrote:
> Adriano Mitre wrote:
>
> > Besides, I would like to know how to undefine Song class, so that
> > Song.new produce a NameError, i.e., behaving as if it were never
> > defined.
>
> You can redefine a class entirely by giving it a new subclass.
> 
>   class Song < Object
>   end

s/subclass/superclass/

T.