binary.rb

#pry -r'./lib/binary'
#[1] pry(main)> Binary.new('foo').to_decimal
#=> 0
#[2] pry(main)> Binary.new('01010').to_decimal
#=> 10
#[3] pry(main)> Binary.new('foo110').to_decimal
#=> 0
class Binary
  attr_accessor :number

  def initialize(number)
    @number = number
  end

  def to_decimal
    return 0 unless @number[/^[01]+/]
    binary_to_decimal
  end

  private

  def binary_to_decimal
    number_array.each_with_index.inject(0) do |results, (obj, index)|
      results += power_of_two_array[index] if obj == 1
      results
    end
  end

  def power_of_two_array
    (0..number_array.size - 1).to_a.map { |e| 2**e }.reverse
  end

  def number_array
    @number.to_s.each_char.map(&:to_i)
  end
end