General programming question - circular referencing

[olsonpm]

So i've ran into this situation before, but never really worried about it. Basically I'm working on creating my own sudoku solver to learn vb.net. I decided to have an element class which represents a single square in the puzzle. That element then has references to three lists which can be validated (no duplicate numbers). The three lists then would be its corresponding row/column/subGrid. Each list then holds a reference to 9 elements. Thus in my design an element has a reference to a list, which then holds a reference to that same element. Now vb.net will allow me to do this so I don't think it is the same issue that I saw when searching for solutions to circular referencing. However, I still wonder whether or not this is bad design. Any info will be much appreciated.

thank you,
Phil

 

[jmcilhinney]

Having two objects referring to each other is not specifically a problem, and does happen in the Framework. For instance, a form has a Controls property that is a collection that refers to each child control. Each of those child controls has a Parent property that refers to the form. It would only be a problem if you were to implement it in such a way that navigating the hierarchy meant encountering the same object twice. In that case you would end up in an infinite loop, which is obviously bad. In the case I mentioned, if you navigate from the top down or the bottom up, you'll only ever touch each control at most once, so there's no issue.

 

[olsonpm]

As always, you are a great help.

Phil