module Polyfill
  module V2_4
    module Float
      module Instance
        module Truncate
          module Method
            def truncate(ndigits = 0)
              ndigits = ndigits.to_int
              return super() if ndigits == 0

              if ndigits > 0
                place = 10**ndigits
                (self * place).truncate / place.to_f
              else
                place = 10**-ndigits
                (self / place).truncate * place
              end
            end
          end

          refine ::Float do
            include Method
          end

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