Refactoring Day 1 : Encapsulate Collection

In certain scenarios it is beneficial to not expose a full collection to consumers of a class. Some of these circumstances is when there is additional logic associated with adding/removing items from a collection. Because of this reason, it is a good idea to only expose the collection as something you can iterate over without modifying the collection. Let’s take a look at some code  
   1: public class Order    2: {    3:     private List<OrderLine> _orderLines;    4:      5:     public IEnumerable<OrderLine> OrderLines    6:     {    7:         get { return _orderLines; }    8:     }    9:     10:     public void AddOrderLine(OrderLine orderLine)   11:     {   12:         _orderTotal += orderLine.Total;   13:         _orderLines.Add(orderLine);   14:     }   15:     16:     public void RemoveOrderLine(OrderLine orderLine)   17:     {   18:         orderLine = _orderLines.Find(o => o == orderLine);   19:         if (orderLine == null) return;   20:     21:         _orderTotal -= orderLine.Total   22:         _orderLines.Remove(orderLine);   23:     }   24: } 
As you can see, we have encapsulated the collection as to not expose the Add/Remove methods to consumers of this class. There is some other types in the .Net framework that will produce different behavior for encapsulating a collection such as ReadOnlyCollection but they do have different caveats with each. This is a very straightforward refactoring and one worth noting. Using this can ensure that consumers do not mis-use your collection and introduce bugs into the code.