Jeff Dean's Ruby Blog - DelegateClass rocks my world

Jeff Dean's Ruby Blog - DelegateClass rocks my world

If you notice that your classes have more than one responsibility, you can easily split them up into multiple, more cohesive classes using Ruby's DelegateClass. Let's say that you have a Person class, and that people in your system can sell things and/or publish articles. You can't use subclasses, because a person can be an author and a seller at the same time. At first you might start with something like this: class Person < ActiveRecord::Base has_many :articles has_many :comments, :through => :articles has_many :items has_many :transactions def is_seller? items.present? end def amount_owed # => some fancy math end def is_author? articles.present? end def can_post_article_to_homepage? # => some fancy permissions end end This might seem OK at first. You might say "Well, it's the responsibility of Person to know about both the items they've sold, as well as the articles the...

Full article: http://pivotallabs.com/users/jdean/blog/articles/1138-del...