Question

I’ve got 2 classes (MyClass1 and MyClass2) that both inherit from MyBaseClass.

I want to write a function that takes a List of either of these as a parameter, like this

private void DoStuff(List<MyBaseClass> input)

{

...

}

How do I pass a List to this function?

Answer 1

You can’t do it quite like that, as a List<MyClass1> isn’t a List<MyBaseClass>. Search on Stack Overflow for generic variance for explanations of why that’s the case.

One thing you can do is make it generic:

private void DoStuff<T>(List<T> input) where T : MyBaseClass

Alternatively, in C# 4 and .NET 4, if you only need to iterate over it, you could use IEnumerable<T> which is covariant in T:

private void DoStuff(IEnumerable<MyBaseClass> input)