.NET: ProjectionEqualityComparer<T>

ProjectionEqualityComparer.cs

public class ProjectionEqualityComparer<T> : IEqualityComparer<T>
{
    Func<T, object> _projector;
    public ProjectionEqualityComparer(Func<T, object> projector)
    {
        this._projector = projector;
    }

    public bool Equals(T x, T y)
    {
        if (x == null || y == null) return (x == null && y == null);

        return object.Equals(_projector(x), _projector(y));
    }

    public int GetHashCode(T obj)
    {
        return _projector(obj).GetHashCode();
    }
}