Some time ago, someone asked me why the following doesn’t work in C#:
List<BaseType>myList = new List<DerivedType>
As I didn’t know this either, I turned to google and came across a very interesting blog from Rik Byers explaining the reasons behind this some more. Today, I noticed a related posting where
Rik shows a workaround for a very common usage of this type of conversion, namely passing a generic list of some derived type to a method that expects a list of the base type. The following won’t work
public int DoSomething(List<BaseType> list) {
foreach (BaseType element in list) {
...
}}
Using a generic method, you can still accomplish the same effect though:
public int DoSomething<T> (List<T> list) where T: BaseType {
foreach (BaseType element in list) {
...
}}
