Can you create a simple 'EqualityComparer' using a lambda expression

Question

Short question:

Is there a simple way in LINQ to objects to get a distinct list of objects from a list based on a key property on the objects.

Answer 1

What about a throw away IEqualityComparer generic class?

public class ThrowAwayEqualityComparer : IEqualityComparer
{
  Func comparer;

  public ThrowAwayEqualityComparer(Func comparer)   
  {
    this.comparer = comparer;
  }

  public bool Equals(T a, T b)
  {
    return comparer(a, b);
  }

  public int GetHashCode(T a)
  {
    return a.GetHashCode();
  }
}

So now you can use Distinct with a custom comparer.

var distinctImages = allImages.Distinct(
   new ThrowAwayEqualityComparer((a, b) => a.Key == b.Key));

You might be able to get away with the , but I'm not sure if the compiler could infer the type (don't have access to it right now.)

And in an additional extension method:

public static class IEnumerableExtensions
{
  public static IEnumerable Distinct(this IEnumerable @this, Func comparer)
  {
    return @this.Distinct(new ThrowAwayEqualityComparer(comparer);
  }

  private class ThrowAwayEqualityComparer...
}