How to get an object from a list based on IEqualityComparer <T>

Question

The Linq comparison method allows you to find IEqualityComparer, but I cannot find the counterparty method that allows you to get an element with the same mapping.

Is this really the best way to do this?

MyItem myFinderItem = new MyItem(keyField1, keyField2); if (myList.Contains(myFinderItem, new MyEqualityComparer())) { MyItem myRealItem = myList.Single(item => new MyEqualityComparer().Equals(item , myFinderItem)); } 

(I am using IEqualityComaprer with the Except Linq method call, and I would like to support a single source for comparing equalities)

Edit: what I'm looking for for a method that has a signature:

 T Find<T>(T t, IEqualityComparer<T> comparer) 

Edit2: I think it works, it's funky . but it is terrible and will never use it :(

 myList.Intersect( new List<MyItem>{myFinderItem}, comparer).Single(); 

Answer 1

First, you should use the same instance of MyEqualityComparer , and not create a new instance each time (maybe you should consider making it single).

Other than that, I don't think there is a much better way to do this. If you want to make it shorter and more readable, you can create an extension method in which instead of <predicate instead of IEquaityComparer<T> :

 public static T Single<T>(this IEnumerable<T> source, IEqualityComparer<T> comparer, T value) { return source.Single(item => comparer.Equals(item, value)); }