Questions Surrounding NotInheritable

[dday9]

I've been developing in VB.NET for a while now (check the VBF join date), but I've only recently started using AI to help me develop. Something I do very frequently is give an LLM a database schema definition and tell it to give me the corresponding .NET POCO definition. It spits out the accurate definition probably 95% of the time in less than 30 seconds and greatly simplifies a tedious part of my job.

When I was doing this in C#, I noticed that the generated code included the sealed modifier in the class, but when I'd do the same thing in VB.NET it omitted it. Doing some digging, I found that there is a corresponding MustInherit modifier, but I wanted to get some clarification rather than using it carte-blanche.

I can understand using it for performance reasons, e.g. I have a class and nothing's inheriting it, then mark it as MustInherit and JIT can presumably do its thing to make the code more performant. Then if I ever need to inherit it, then I can remove the modifier from the parent class and add it to the child class.

But I'm wondering about other use cases when the MustInherit modifier makes sense, and I was hoping for some input.

[Zvoni]

Uh..."sealed" in C# is definitely not the equivalent of "MustInherit" in VB, it's actually more of an opposite

"sealed" in C#:
1) "sealed" in class-declaration: Prevents OTHER classes inheriting from it --> I'm a "sealed" Person --> Nope. No children from me. Period!
2) "sealed" on a Function inside the class: Prevents derived classes from overriding it

"MustInherit" in VB: Declares the Class to be abstract, and CANNOT be instantiated directly --> I'm a "MustInherit" Person --> Don't talk to me, ever! Talk to my children!

A "MustInherit"-Class is more like a Template

https://learn.microsoft.com/en-us/do...eywords/sealed
https://learn.microsoft.com/en-us/do...rs/mustinherit

You probably meant "NotInheritable" (as actually mentioned in your Thread-Subject)
https://learn.microsoft.com/en-us/do...notinheritable

Difference between C# ("sealed") and VB ("NotInheritable"): in VB it's only valid in the Class statement. You cannot seal single Functions like in C#
otherwise if "sealed" (C#) is in the class-declaration, then it's equivalent to "NotInheritable" in VB

though it escapes me how i compiler can gain performance by using it

IMO, using "NotInheritable" in this context makes only sense if you are a developing a component, which is/will be used by OTHER programmers, and you want to protect your component from those programmers trying to change its behavior