gistfile1.txt

#! /usr/bin/env ruby
#
# This code works (or fails!) differently on MRI, Rubinius and JRuby,
# also depending on whether the Fixnum monkey-patches are included.
# Note that the patches exist to apply a to_i to the parameter of Fixnum@eql?
#
# If Ruby's Hash claims to use only "hash" and "eql?" to store and find
# items, why can't the Ruby interpreters agree on *how*?
#
# In particular:
# 1) If Fixnum has a patched version of either method, any
# internal optimisations should be disabled.
#
# 2) the eql? method should be called only on the values
# actually stored in the hash, or only on the value we're
# using as a key. It should not use both, and it should not
# be indeterminate which one will be used.
#
class Number
  def initialize(i)
    @i = i
  end

  def eql?(a)
    print "  <Number #{@i.inspect}>.eql?(#{a.inspect})"
    v = @i.eql?(a.to_i)
    puts " => #{v.inspect}"
    v
  end

  def to_i
    @i
  end

  def hash
    print "  Getting Number(#{@i}).hash()"
    v = @i.hash
    puts " => #{@i.hash}"
    v
  end
end


class Fixnum
  alias :orig_eql? :eql?

  def eql?(i)
    print "  <Fixnum #{inspect}>.eql?(#{i.inspect})"
    v = self.orig_eql?(i.to_i)
    puts " => #{v.inspect}"
    v
  end

  alias :orig_hash :hash
  def hash
    print "  <Fixnum #{inspect}>.hash"
    v = orig_hash
    puts " => #{v.inspect}"
    v
  end
end

puts "Populating the hash:"
h = {}
20.upto(30) {|i| h[Number.new(i)] = true }

puts
puts "Looking up using Integer:"
i = 23
p h[i]

puts "Looking up using Number.new(23):"
p h[Number.new(23)]