Make something enumerable

Created on February 20, 2022

Updated on February 20, 2022

Tags: ruby

It can sometimes be useful for an object to be Enumerable, so we can call methods like map, max, etc. There’s basically two steps:

include Enumerable
Define an each method. Enumerable methods rely on each.

This example comes from an exercise I did on Exercism.

class CharSet
  include Enumerable

  def initialize(text)
    @text = text
    @members = text.split("\n").map(&:chars)
  end

  def each(&block)
    if block_given?
      @members.each(&block)
    else
      to_enum(:each)
    end
  end

  def max_length
    map(&:length).max || 0
  end

  def transpose
    max_length.times.each_with_object([]) do |n, a|
      a << Row.new(map { |member| member[n] })
    end
  end
end

Alex's Slip-box

Make something enumerable

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