Use simple & useful ruby methods such as basename in RubyMotion

Use simple & useful ruby methods such as basename in RubyMotion

RubyMotion does not support
require
in code (only in RakeFile).
Is there a way to use useful classes built into Ruby but not into
RubyMotion ? For instance, I'd like to be able to do a
name=Pathname.new("/path/to/some/file").basename
rather than look for Cocoa equivalent