Question

Can someone explain me this Ruby on Rails puzzle?

 class Post < ActiveRecord::Base
   has_many :comments
 end

 Post.first.comments.class
 => Array

 Array === Post.first.comments
 => false

 Array === [ 1 ]
 => true

Answer 1

Post.first.comments is a delegator. It does not give you back an Array directly, but if you do anything with it, it turns into one. This is useful because it lets you do stuff like

Post.first.comments.all(:conditions => {:author_name => 'RJH'})

without having to inject those methods into the array object, or extending the Array class.