lookup-hash is intended for using as fast lookup table for simple checking of existency of some item inside. It doesn't bring any additional performance, it's defacto only Hash with booleans, but it's better and more readable to write:

require "lookup-hash"
allowed = LookupHash[:alfa, :beta]

…than:

require "lookup-hash"
allowed = Hash[:alfa, true, :beta, true]

Other methods are equivalent to Hash with exception of data assignment methods which convert all values to booleans. New key it's possible to add also by:

hash << :key    # …or…
hash.add(:key)

Implicitly frozen lookup hash is available as Frozen::LookupHash in lookup-hash/frozen.

1. Fork it.
2. Create a branch (git checkout -b 20101220-my-change).
3. Commit your changes (git commit -am "Added something").
4. Push to the branch (git push origin 20101220-my-change).
5. Create an Issue with a link to your branch.
6. Enjoy a refreshing Diet Coke and wait.

Copyright © 2011 Martin Kozák. See LICENSE.txt for further details.