Inheritance with static classes

Question

I don't know whether this question will make sense or if it's a naive question, but I haven't been able to find a satisfactory answer.

I would like to be able to share code across multiple static classes. Is there an "equivalent" of an abstract base class for static classes (i.e. can I have one static class inherit from another one)? If not, why not? Is there another way of sharing code across multiple static classes in a manner analogous to what you do with an abstract base class?

Also, how does a static class compare to a "sealed" class?

What exactly _is_ your question? `sealed` classes cannot be inherited, that's the whole reason for the `sealed` keyword to exist. — René Vogt, Sep 12 '16 at 12:38
A `sealed` class is, by definition a class from which you cannot inherit. What exactly is your question? — npinti, Sep 12 '16 at 12:38
"The sealed modifier prevents other classes from inheriting from it" https://msdn.microsoft.com/en-gb/library/88c54tsw.aspx Whereas an "abstract class must be inherited by a class that provides an implementation of the abstract methods or properties". — Paul Zahra, Sep 12 '16 at 12:38
i think i have clarified the question, in place of static i typed sealed — Nishant Kumar, Sep 12 '16 at 13:00

score 5 · Accepted Answer · edited Sep 12 '16 at 18:19

5

You're quite right. Reflection will show that a static class is both abstract and sealed:

  public static class MyStaticTest {
  }

  ...

  // I'm abstract
  Console.WriteLine(typeof(MyStaticTest).IsAbstract ? "I'm abstract" : "");

and that's why you can't create an instance (compile time error): new MyStaticTest();. However, reflection will show that any static class is sealed as well:

 // I'm sealed 
 Console.WriteLine(typeof(MyStaticTest).IsSealed ? "I'm sealed" : "");

and so you can't inherit from it (compile time error): public class MyClass: MyStaticTest {..}. Thus, all you can do with static class is to declare static members (static fields, properties, methods etc.)

edited Sep 12 '16 at 18:19

EJoshuaS - Stand with Ukraine

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answered Sep 12 '16 at 12:46

Dmitry Bychenko

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`any abstract class is sealed one as well` I think you mean static, instead of abstract. – Jonesopolis Sep 12 '16 at 12:56
@Jonesopolis: I'm sorry for typo, any `static` (not `abstact`) class is `sealed` one; need more coffee – Dmitry Bychenko Sep 12 '16 at 12:59
no need to be sorry, it was a very helpful answer – Jonesopolis Sep 12 '16 at 12:59
I didn't know static classes are both sealed and abstract. A very helpful answer indeed! – Stack Undefined Nov 06 '21 at 15:58

score 0 · Answer 2 · edited Sep 12 '16 at 13:10

0

The abstract keyword enables to create classes and class members that are incomplete and must be implemented in a derived class whereas The sealed keyword enables you to prevent the inheritance of a class or certain class members that were previously marked virtual.

I think its complete for Above

edited Sep 12 '16 at 13:10

durg

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answered Sep 12 '16 at 12:45

Bman

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Abstract and Sealed Keyword Plays the main role . – Bman Sep 12 '16 at 12:58

Inheritance with static classes

2 Answers2