Sandy Metz's OOP Rules (src: http://rubyrogues.com/087-rr-book-clubpractical-object-oriented-design-in-ruby-with-sandi-metz/)

gistfile1.txt

- classes can be no longer than 100 lines
- methods can be no longer than 5 lines
- methods cannot accept more than 4 parameters (no gigantic hashes)
- controllers cannot instantiate more than 1 object
- views cannot know about more than 1 instance variable
- views should only send messages to that variable (no Demeter violations)
- rules are meant to be broken if by breaking them you produce better code