Sort a List by enum where enum is out of order

Question

I have a List of messages. Each message has a type.

public enum MessageType
{
    Foo = 0,
    Bar = 1,
    Boo = 2,
    Doo = 3
}

The enum

Answer 1

Instead of using an IComparer, you could also use a SelectMany approach, which should have better performance for large message lists, if you have a fixed number of message types.

var messageTypeOrder = new [] {
    MessageType.Boo,
    MessageType.Bar,
    MessageType.Foo,
    MessageType.Doo,
};

List tempList = messageTypeOrder
    .SelectMany(type => messageList.Where(m => m.MessageType == type))
    .ToList();