case_comparator.rb

class CaseComparator
  def initialize(object, operator)
    @object = object
    @operator = operator
  end

  def ===(other)
    other.send(@operator, @object)
  end
end

class Object
  def cc(operator)
    CaseComparator.new(self, operator)
  end
end

loop do
  print "Enter a number: "
  case gets.strip.to_i
  when 5.cc(:>)
    puts "More than 5!"
  when 3.cc(:>)
    puts "More than 3!"
  else
    puts "Less :("
  end
end