gistfile1.rb

module Enumerable
  def uniq_by(&blk)
    inject({}) {|h, o| h.update(blk.call(o) => o) }.values
  end
end

if $0 == __FILE__
  require "rubygems"
  require "spec"

  class Thing
    attr_reader :x
    def initialize(x)
      @x = x
    end
  end

  describe Enumerable do
    describe "uniq_by" do
      it "provides an array of unique objects based on the value of a block" do
        things = (1..3).map {|n| Thing.new(n) } * 3
        things.uniq_by {|t| t.x }.map {|t| t.x }.should == [1, 2, 3]
      end
    end
  end

  Spec::Runner::CommandLine.run
end