From: Jeremy Kemper <jeremy@...>
Date: 2005-04-28T11:45:10+09:00
Subject: Re: Hash as Checklist

basi wrote:
> I need to check if a word is in a list. I'm using hash because the
> lists can be long (i'm under the impression hash is faster than array).
> Basically I'm only interested that a key exists. I have to create
> entries like:
> 
> h = {
> "one" => true,
> "two" => true,
> "three" => true,
> "four" => true,
> "five" => true
> }
> 
> So h["one"] gives true, and h["seven"] returns nil. But typing the
> dummy value "true" is a waste of effort, and there's an ugliness in
> there. Is there a better way to design a simple checklist?

Use a set:
  require 'set'
  words = %w(one two three four five).to_set
  words.include? 'one'    # => true
  words.include? 'seven'  # => false

http://www.ruby-doc.org/stdlib/libdoc/set/rdoc/

jeremy