Exercisme: palindromes exercise

palindrome_products.rb

class Palindromes
  private

  attr_reader :factors, :max_factor, :min_factor, :palindromes

  def initialize(min_factor: 1, max_factor: 1)
    @min_factor = min_factor
    @max_factor = max_factor
    @factors = (min_factor..max_factor).to_a
    @palindromes = palindromes
  end

  def pairs_by_product
    factors.product(factors)
           .uniq(&:sort)
           .group_by { |f1, f2| f1 * f2 }
  end

  def palindrome?(number)
    number.to_s == number.to_s.reverse
  end

  public

  def generate_lazy
    @palindromes = pairs_by_product.lazy
                                   .map { |product, pairs| Product.new(product, pairs) }
                                   .select(&:palindrome?)
  end

  def generate_no_lazy
    @palindromes = pairs_by_product
                   .map { |product, pairs| Product.new(product, pairs) }
                   .select(&:palindrome?)
  end

  def palindromes
    pairs_by_product
     .map { |product, pairs| Product.new(product, pairs) }
     .select(&:palindrome?)
  end

  def generate_initalize_memo
    @palindromes = pairs_by_product
                   .map { |product, pairs| Product.new(product, pairs) }
                   .select(&:palindrome?)
  end

  def smallest
    palindromes.min
  end

  def largest
    palindromes.max
  end
end

class Product
  include Comparable

  private

  def initialize(value, factors)
    @value = value
    @factors = factors
  end

  public

  attr_reader :value, :factors

  def palindrome?
    value.to_s.reverse == value.to_s
  end

  def <=>(other)
    value <=> other.value
  end
end

if $PROGRAM_NAME == __FILE__
  require 'benchmark/ips'
  
  gwl = Palindromes.new
  gwol = Palindromes.new
  gmim = Palindromes.new
  #gim = Palindromes.new

  Benchmark.ips do |x|
    x.report('generate with lazy') { gwl.generate_lazy }
    x.report('generate without lazy') { gwol.generate_no_lazy }
    x.report('generate memoized in method') { gmim.palindromes }
    #x.report('generate initialize_memo') { gim.generate_initalize_memo }
    x.compare!
  end
end

Sent an RFC (Request for Comment) patch to you for this, so that you can apply it to this repository (I, of course, have no access and so can not do so directly, but can if you apply the patch(es).)