Testing gist on tumblr with this nifty hash is a cache bit of code.

hashascache.rb

#!/usr/bin/ruby

@users = Hash.new do |cache, user_id|
    data = "NEW"
    cache[user_id] = data
    puts "created #{user_id}"
end

test = @users[10]
test = @users[20]
test = @users[10]
test = @users[30]