RangedHash implementation in Ruby

ranged_hash.rb

class RangedHash
  def initialize(hash={})
    @ranged_hash = hash
  end

  def [](key)
    (@ranged_hash.detect{|range, value| range.cover?(key) } || []).last
  end

  def []=(key, value)
    @ranged_hash[key] = value
  end
end