ruby-stb-lib forwardable

forwardable.rb

require 'forwardable'

class A
  extend Forwardable

  def initialize
    @arr =  Array.new
  end

  def_delegator :@arr, :push, :add
  def_delegators :@arr, :size, :map
end

a = A.new
puts a.size # 0
puts a.add('a') # a
puts a.size # 1
puts a.map(&:to_s) # a

class B
  extend SingleForwardable

  def self.arr
    @arr ||= Array.new
  end

  def_delegator :arr, :push, :add
  def_delegators :arr, :size, :map
end

puts B.size # 0
puts B.add('a') # a
puts B.size # 1
puts B.map(&:to_s) # a

=begin
 if you extend both
   use def_instance_delegator and def_single_delegator
 end
=end