case with predicates

gistfile1.rb

require 'rubygems'
require 'backports'  # aliases Proc#=== to Proc#call

rs = (0..10000).to_a.sample(30)

rs.each do |r|
  case 
  when r.zero?        then puts "#{r} is zero"
  when (r % 5).zero?  then puts "#{r} is fiven"
  when (r % 4).zero?  then puts "#{r} is fourven"
  when (r % 3).zero?  then puts "#{r} is threeven"
  when r.even?        then puts "#{r} is even"
  when r.odd?         then puts "#{r} is odd"
  else
    raise 'unpossible'
  end
end