User with paperclip attachment using proc for default_url

user.rb

has_attached_file :avatar,
  :styles      => { :medium => "100x100#", :thumb => "45x45#" }
  :default_url => lambda { |a| "/images/avatar_:style_#{a.instance.default_image_number}.png" }

def default_image_number
  id.to_s.last
end

# this example allows you to have 10 random default avatars:
# avatar_thumb_0.png, avatar_thumb_1.png, etc.
# avatar_medium_0.png, avatar_medium_0.png, etc.

Come on, thoughtbot, accept the pull request already!!! :-)

+1