Ruby/Collections/Forwardable

require "forwardable"
class WriterDecorator
  extend Forwardable
  def_delegators :@real_writer, :write_line, :rewind, :pos, :close
  def initialize(real_writer)
   @real_writer = real_writer
  end
end

require "forwardable"
class AppendOnlyArray
  extend Forwardable
  def initialize
    @array = []
  end
  def_delegator :@array, :<<
end
a = AppendOnlyArray.new
a << 4
a << 5

require "forwardable"
class RandomAccessHash
  extend Forwardable
  def initialize
    @delegate_to = {}
  end
  def_delegators :@delegate_to, :[], "[]="
end
ra = RandomAccessHash.new
ra["A"] = 4.60
ra["B"] = 1.94
ra["C"] = 2.01
puts ra["D"]