module Polyfill
  module V2_4
    module Enumerable
      module Instance
        module Sum
          module Method
            def sum(init = 0)
              acc =
                begin
                  init.dup
                rescue TypeError
                  init
                end

              each do |elem|
                acc += block_given? ? yield(elem) : elem
              end

              acc
            end
          end

          refine ::Dir do
            include Method
          end
          refine ::Enumerator do
            include Method
          end
          refine ::Hash do
            include Method
          end
          refine ::IO do
            include Method
          end
          refine ::Range do
            include Method
          end
          refine ::StringIO do
            include Method
          end
          refine ::Struct do
            include Method
          end

          def self.included(base)
            base.include Method
          end
        end
      end
    end
  end
end