title: Cross referencing objects management
body: <p>Often I would have an unit and node object. Units are required to know which node they are at and nodes have to know the units its holding. This means that they each have a reference to each other. The problem I have is that I can see this getting messy since moving a unit to a new node means also having to update the reference for the nodes too. Is there a easier way to model/organize this relationship? This specific example is in lua but the question applies to any language.</p>