Convert Hex to Decimal

hex.rb

class Hex
  HEX = { '1' => 1, '2' => 2, '3' => 3,
          '4' => 4, '5' => 5, '6' => 6,
          '7' => 7, '8' => 8, '9' => 9,
          'a' => 10, 'b' => 11, 'c' => 12,
          'd' => 13, 'e' => 14, 'f' => 15 }

  attr_reader :string

  def initialize(input)
    @string = input.downcase
  end

  def to_decimal
    return 0 if string.match(/[^0-9a-f]/)
    string.split('').reverse
                    .each_with_index.map { |character, index| HEX[character] * 16 ** index }
                    .inject(&:+)
  end
end

result = Hex.new('abcde2342').to_decimal
puts result

Nice. Is there a preference between split('') and chars?