Listify

Working on our latest Sinatra project, I came across the need to turn an array of words into a list to plug into a sentence. I like to crib Rails code whenever possible, because the project has a ton of useful extensions for this type of task, however I couldn’t find anything that exists for turning arrays into an English style list. So for that I came up with listify!

class Array
  def listify
    length < 2 ? first.to_s : "#{self[0..-2] * ', '} and #{last}"
  end
end

Listify is an extension to Ruby’s Array class, and it will take an array of words, and turn them into a human readable list, along with the proper grammatical conventions as put forth by William Strunk. Usage is thusly:

["dave"].listify
#=> "dave"

["dave", "bill"].listify
#=> "dave and bill"

["dave", "bill", "murray"].listify
#=> "dave, bill, and murray"

Update – Turns out that I didn’t look hard enough in Rails. Rails has a method called to_sentence which accomplishes the same end as noted above. The Rails version is great if you’re working in a Rails environment, or if you want to bring ActiveSupport into your project as a dependency.

Update 2 – Peter Cooper pointed out that my Stunk usage was incorrect for two commas, and added a nice little golf solution. I’ve updated the post to reflect this feedback. Thanks everyone for the constructive criticism!