Continuation based Fiber implementation for Ruby 1.8

gistfile1.rb

class Fiber
  def initialize &blk
    unless @yield = callcc{|c| c }
      @ret = blk.call(@ret)
      @resume.call
    end
  end

  def resume *args
    if @resume = callcc{|c| c }
      Thread.current[:fiber] = self
      @ret = args.size > 1 ? args : args.first
      @yield.call
    else
      @ret
    end
  end

  def yield *args
    if @yield = callcc{|c| c }
      @ret = args.size > 1 ? args : args.first
      @resume.call
    else
      @ret
    end
  end

  def self.yield *args
    Thread.current[:fiber].yield *args
  end
end

f = Fiber.new{ |sym|
  p(sym)
  puts 'hi'
  p(Fiber.yield 1)
  puts 'bye'
  :end
}
p(f.resume :begin)
p(f.resume 2)

__END__

:begin
hi
1
2
bye
:end