caesar_cipher.rb

class CaesarCipher

    @@alphabet = ("A".."Z").to_a

    def initialize(input, shift_num)
      @input, @shift_num = input.upcase, shift_num
    end

    def encrypt
      shift_things_around
    end

    def decrypt
      @shift_num = 26 - @shift_num
      shift_things_around
    end
  
    private
  
    def shift_things_around
      @shift_num.times { @@alphabet.push(@@alphabet.shift) }
      puts @input.tr('A-Z', @@alphabet.join)
    end

  end