Why cant I declare a generic list as nullable?

Question

Im trying to use the following code:

private Nullable<List<IpAddressRange>> ipAddressRangeToBind; 

But I am getting the following warning:

The type List must be a non-nullable value type in order to use it as a parameter 'T' in the generic type or method 'System.Nullable'.

Answer 1

List<T> is already a reference type (for any kind of T) - you can only declare Nullable<T> where T is a non-nullable value type (it's declared as Nullable<T> where T : struct).

But that's okay, because if you just declare:

private List<IpAddressRange> ipAddressRangeToBind; 

then you can still have

ipAddressRangeToBind = null; 

because reference types are always nullable.