IEqualityComparer for anonymous type

Question

I have this

 var n = ItemList.Select(s => new { s.Vchr, s.Id, s.Ctr, s.Vendor, s.Description, s.Invoice }).ToList();
 n.AddRange(OtherList.Select(s =>          


        

Answer 1

Most of the time when you compare (for equality or sorting) you're interested in choosing the keys to compare by, not the equality or comparison method itself (this is the idea behind Python's list sort API).

There's an example key equality comparer here.