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When creating generic classes, you might need some more C# keywords

a. Default values: - It is not possible to assign null to generic type

- We can use default keyword to initialize default(either 0 or null) value

b. Constraints – If Generic class needs to invoke some methods from the generic type we have to add constraints.

where T: struct With a struct constraint, type T must be a value type.

where T: class Class constraint indicates that type T must be a reference type.

where T: IFoo where T: IFoo specifies that type T is required to implement interface IFoo.

where T: Foo where T: Foo specifi es that type T is required to derive from base class Foo.

where T: new() where T: new() is a constructor constraint and specifies that type T must have a default constructor.

where T1: T2 With constraints it is also possible to specify that type T1 derives from a generic

type T2. This constraint is known as naked type constraint.

c. Inheritance: - A generic type can implement a generic interface.

- When deriving from generic base class, you must provide a type argument instead of the base-class’s generic type parameter.

public class LinkedList<T>: IEnumerable<T>

{//...

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<T> { }

public class Derived<T>: Base<T> { }

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<T>

{

public abstract T Add(T x, T y);

public abstract T Sub(T x, T y);

}

public class IntCalc: Calc<int>

{

public override int Add(int x, int y)

{

return x + y;

}

public override int Sub(int x, int y)

{

return x — y;

}

}

d. Static Members – static members of generic class are only shared with one instatiation of the class.

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