// This example illustrates how worlds may be used to implement Krishna's "versioning exceptions".


eval(readFile("Worlds_Compiled"))

w = new world
try {
  in w {
    // Do stuff that will be rolled back if an exception is thrown.
    x = 5
    throw "argh!"
  }
}
catch (e) {
  // Handle the exception (the try block will have had no effect).
  alert("an exception was thrown!")
  // Null out w to signal (that way the finally knows its changes should not be committed).
  w = null
}
finally {
  // If the try block did not throw an exception, commit w's changes.
  if (w != null)
    w.commit()
}