A magnitude-comparison monkey-patch for Ruby's case. Suggested at http://swhack.com/logs/2013-01-28#T23-17-31

gistfile1.rb

# usage:
#
# case compare(2,3)
# when :>
#   puts "greater"
# when :<
#   puts "less"
# when :==
#   puts "same"
# end
# # => prints "less"
#
# you can have any number of numbers in the compare expression

class CaseComparer
  def initialize *ns
    @numbers = ns
  end
  
  def === comparer
    @numbers.each_cons(2).all? {|x, y| x.method(comparer).call(y) }
  end
end

# ugh
class Symbol
  @@oldtripeq = method :===
  def === *args, &block
    x = args.first
    if x.is_a? CaseComparer
      x === self
    else
      @@oldtripeq.call *args, &block
    end
  end
end

def compare *ns; CaseComparer.new *ns; end