To reinvent the if expression as method call

ifmethod.rb

module IfMethod
  Done = Object.new
  NotYet = Object.new
  Noop = Proc.new {}
  DoneWith = Object.new

  def self.proc_if(cond, tblk)
    if cond then
      tblk.call
      Done
    else
      NotYet
    end
  end

  def self.proc_else(arg, fblk, &ret)
    if arg.empty? then
      fblk.call
      nil
    else
      ret.call(arg[0])
    end
  end

  def Done.else(*arg, &fblk)
    IfMethod.proc_else(arg, Noop) { |x| DoneWith }
  end
  def NotYet.else(*arg, &fblk)
    IfMethod.proc_else(arg, fblk) { |x| x }
  end
  def DoneWith.if(&tblk)
    Done
  end
end
class Object
  def if(&tblk)
    IfMethod.proc_if(self, tblk)
  end
end

test-ifmethod.rb

load 'ifmethod.rb'
def test1(n)
  (n < 10).if {
    p 'small'
  }.else(n < 100).if {
    p 'medium'
  }.else {
    p 'big'
  }
end
test1(3)
test1(33)
test1(333)