I'm trying to implement the RaiseMan example from Aaron Hillegass's book in MacRuby. All has gone pretty well until I reached undo. The idea is to handle the insertObject message each time a Person is inserted and manipulate the undo stack.

  def insertObject(p, inEmployeesAtIndex:index)
    NSLog("adding #{p} to #{employees}") # <= Not called, huh?
    undo = @undoManager
    undo.prepareWithInvocationTarget(self, removeObjectFromEmployeesAtIndex:index)
    if !undo.isUndoing
      undo.setActionName("Insert Person")
    end
    employees.insertObject(p, atIndex:index)
  end

The Objective-C signature for this is:

- (void)insertObject:(Person *)p inEmployeesAtIndex:(int)index

Works in Objective-C but in my Ruby, the method is not recognized as a handler to be invoked when a Person object is to be inserted in the employees array. I should note that I created the employees array using Ruby syntax:

@employees ||= []

Changing this to:

@employees ||= NSMutableArray.alloc.init

makes no difference in this scenario.

Any hints with respect to what I'm missing here?

Thanks,

Steve