Sendmessage

Well, as instance, you could use the object to return the state of the object once the message has been processed.

Imagine this scenario:

Const NoChange:int = 0
Const DeleteShip:int = 1

Type GameEngine
    Field Ships:Tlist 
    ....
    ....
    Method UpdateShips()
        For S:Ship = eachin Ships
            Local Result:UpdateResult = UpdateResult(S.SendMessage("Update"))
            If Result.Status = DeleteShip then
                Ships.Remove(S)
            End If
        Next
    End Method
End Type

Type UpdateResult
    Field Status:Int=NoChange
End Type

Type Ship
    ...
    ...
    Method SendMessage:Object(Message:Object, Param:Object = Null)
        ....
        ....
        If Message = "Update" Then
            Local R:UpdateResult = New UpdateResult
            If ShipCollidedWithLaser then
                R.Status = DeleteShip
                Return R
            Else
                R.Status = NoChange
                Return R
            End If
        End If
    End Method
End Type

this is just a pseudo-code silly example of a possible usage for the sendmessage method