chained comparison in Ruby

chained-comparison.rb

# Chained comparisons in Ruby
# inspired by http://coffeescript.org/#comparisons
# as well as http://refactormycode.com/codes/1284

[:<, :>, :<=, :>=].each do |operator|
  [Float, Fixnum, Rational, Comparable].each do |klass|
    klass.class_eval do
      alias_method "_#{operator}", operator
      define_method operator do |rhs|
        send("_#{operator}", rhs) && rhs
      end
    end
  end
  
  FalseClass.class_eval do
    define_method(operator){|rhs| false }
  end
end


if __FILE__ == $0
  (1..15).each do |x|
    case
    when x <= 5
      puts "#{x} is too low"
    when 5 < x <= 7
      puts "#{x} is low but ok"
    when x == 8
      puts "#{x} is exactly right"
    when 8 < x <= 10
      puts "#{x} is high but ok"
    when x > 10
      puts "#{x} is too high"
    end
  end
end