Question

Often with lists and the items inside them, I find the need to query or find things in the list the object has been added to.

For example:

// create list of levels
IList<Levels> levels = new List<Levels>
{
    levels.Add(new Level{ Depth = 1, Name = "Level 1" });
    levels.Add(new Level{ Depth = 2, Name = "Level 2" });
}

foreach(Level level in levels)
{
    bool lowestLevel = false;

    // would the lowest level be best worked out from a function that takes the list and the level?
    lowestLevel = Level.GetLowest(Levels, level);

    // as a calculated property of level itself where the level knows about the list of levels it's in?
    lowestLevel = Level.IsLowest;

    // or worked out when creating the level?
    // levels.Add(new Level{ Depth = 1, Name = "Level 1", IsLowest = isLowest });
    lowestLevel = Level.IsLowest;
}

Are any of these a ‘best practice’ way to handle something like this or is there another way?

Thanks in advance.

Answer 1

Ignoring the fact that adding to the collection being iterated over throws an exception…

There is definitely another way. When a Level needs to know about its siblings, you should encapsulate levels inside a class, say LevelCollection. You can give each Level a reference to its parent collection when you insert a level into a collection, and stop passing levels in the methods than need the siblings.