manveru's nifty restartable exceptions

restartable.rb

require 'continuation'

class RestartableError < StandardError
  attr_accessor :cc

  def self.call(msg)
    instance = new(msg)
    returning = true
    callcc{|c| instance.cc = c }
    returning = !returning
    raise instance unless returning
  end
end

class Foo
  def a
    puts "everything fine a"
    RestartableError.call("omg!")
    puts "everything fine b"
  end
end

begin
  Foo.new.a
rescue RestartableError => ex
  p ex
  p ex.cc.call
end