When you need to split class into seveal parts... New file:
ClassPart = proc do <copy here code you want to move out of the main class> end
class MainClass class_eval &ClassPart ... end
I used this approach to create a recycled bin: when i find some functionality not very valuable i move it to the 'recycled bin' part of class. i keep it there for a while. then i delete it altogether from code.