Why sealed c

We will also see why developers use sealed classes in their libraries and code. Sealed classes are used to restrict the inheritance feature of object oriented programming. Once a class is defined as a sealed class, this class cannot be inherited. In C , the sealed modifier is used to declare a class as sealed.

In Visual Basic. NET, NotInheritable keyword serves the purpose of sealed. If a class is derived from a sealed class, compiler throws an error. If you have ever noticed, structs are sealed. You cannot derive a class from a struct. If you run this code, it will work just fine. But if you try to derive a class from the SealedClass, you will get an error.

In my opinion it is a mistake in the C language to make classes inheritable by default. Java went even further and made methods virtual by default which appears to many as a design mistake. On a class that implements security features, so that the original object cannot be "impersonated". More generally, I recently exchanged with a person at Microsoft, who told me they tried to limit the inheritance to the places where it really made full sense, because it becomes expensive performance-wise if left untreated.

The sealed keyword tells the CLR that there is no class further down to look for methods, and that speeds things up. In most performance-enhancing tools on the market nowadays, you will find a checkbox that will seal all your classes that aren't inherited. Be careful though, because if you want to allow plugins or assembly discovery through MEF, you will run into problems. Stack Overflow for Teams — Collaborate and share knowledge with a private group.

Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Why do we need sealed classes? Ask Question. Asked 3 years, 2 months ago. By: Justin Stoltzfus Contributor, Reviewer. By: Satish Balakrishnan. Dictionary Dictionary Term of the Day.

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