C# 4 and .NET 4

Generics features ❘ 117
inheritance
The LinkedList class created earlier implements the interface IEnumerable:
public class LinkedList: IEnumerable
{
//...
A generic type can implement a generic interface. The same is possible by deriving from a class. A generic
class can be derived from a generic base class:
public class Base
{
}
public class Derived: Base
{
}
The requirement is that the generic types of the interface must be repeated, or the type of the base class must
be specified, as in this case:
public class Base
{
}
public class Derived: Base
{
}
This way, the derived class can be a generic or non-generic class. For example, you can define an abstract
generic base class that is implemented with a concrete type in the derived class. This allows you to do
specialization for specific types:
public abstract class Calc
{
public abstract T Add(T x, T y);
public abstract T Sub(T x, T y);
}
public class IntCalc: Calc
{
public override int Add(int x, int y)
{
return x + y;
}
}
public override int Sub(int x, int y)
{
return x — y;
}
static members
Static members of generic classes require special attention. Static members of a generic class are only shared
with one instantiation of the class. Let’s have a look at one example, where the class StaticDemo
contains the static field x:
public class StaticDemo
{
public static int x;
}
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