gistfile1.rb

# Ruby tends to pass by reference.
#   http://groups.google.com/group/ruby-talk-google/msg/aa5cdea350f46314
#
# Notice all the same object ID in the output.
#

class Test
  def self.test
    hash = {:entry => ""}
    array = []
    puts "Hash: #{hash.object_id}"
    3.times {
      array << self.test2(hash)
      puts "Hash: #{hash.object_id}"
    }
    array
  end
  def self.test2(hash)
    puts "Hash: #{hash.object_id}"
    hash[:entry] += "Test"
    hash
  end
end

p Test.test

# Hash: 58570
# Hash: 58570
# Hash: 58570
# Hash: 58570
# Hash: 58570
# Hash: 58570
# Hash: 58570
# [{:entry=>"TestTestTest"}, {:entry=>"TestTestTest"}, {:entry=>"TestTestTest"}]