Is named indexer property possible? [duplicate]

Question

Suppose I have an array or any other collection for that matter in class and a property which returns it like following:

public class Foo
{
    public IList<Bar> Bars{get;set;}
}

Now, may I write anything like this:

public Bar Bar[int index]
{
    get
    {
        //usual null and length check on Bars omitted for calarity
        return Bars[index];
    }
}

Answer 1

No - you can't write named indexers in C#. As of C# 4 you can consume them for COM objects, but you can't write them.

As you've noticed, however, foo.Bars[index] will do what you want anyway... this answer was mostly for the sake of future readers.

To elaborate: exposing a Bars property of some type that has an indexer achieves what you want, but you should consider how to expose it:

• Do you want callers to be able to replace the collection with a different collection? (If not, make it a read-only property.)
• Do you want callers to be able to modify the collection? If so, how? Just replacing items, or adding/removing them? Do you need any control over that? The answers to those questions would determine what type you want to expose - potentially a read-only collection, or a custom collection with extra validation.