Prints out a boolean truth table for a given number of variables

combinations.rb

class Combinations
  attr_accessor :number_of_variables

  def initialize(number_of_variables=2)
    @number_of_variables = number_of_variables
  end

  def print_combinations
    combinations.each do |row|
      row.each_with_index do |v, i|
        print "| " if i == 0
        print string_val(v)
        print " | " unless i == number_of_variables
        print "\n" if i == number_of_variables - 1
      end
    end
  end

  def combinations
    ([true, false]*number_of_variables).combination(number_of_variables).to_a.uniq
  end

  def string_val(val)
    if val == true
      "T"
    else
      "F"
    end
  end
end