In java, I could do this with the 'final' keyword. I don't see 'final' in C#. Is there a substitute?
+36
A:
You're looking for the sealed keyword. It does exactly what the final keyword in Java does. Attempts to inherit will result in a compilation error.
Kilhoffer
2008-09-30 19:57:12
+2
A:
As Joel already advised, you can use sealed instead of final in C#.
http://en.csharp-online.net/CSharp_FAQ:_Does_CSharp_support_final_classes
nsr81
2008-09-30 20:09:02
+5
A:
Also be aware that "I don't think anybody will ever need to inherit from this" is not a good reason to use "sealed". Unless you've got a specific need to ensure that a particular implementation is used, leave the class unsealed.
Mark Bessey
2008-09-30 20:19:00
I disagree. Inheritance is often misused., and most classes aren't coded with inheritance in mind. So, unless a class was designed to be inherited, it should be sealed by default. Then, when someone inherits off of your sealed class, it might force them to think about it a little more.
Robert Paulson
2008-09-30 20:49:25
I agree with Robert (i.e. I disagree with Mark). Inheritance is something which takes a great deal of careful consideration. For example, any time you call one virtual method from another, you are locking that implementation - changing the call to be the other way round can break derived classes.
Jon Skeet
2008-09-30 20:51:56
It also **slightly** helps with performance.
MagicKat
2008-09-30 21:10:08
Maybe I've been in the "framework" business for too long, but as far as I'm concerned, any class that's not designed for re-use and subclassing isn't done yet. I'm not convinced that putting "sealed" on every class is going to accomplish much in terms of making people think.
Mark Bessey
2008-09-30 21:11:29
Actually the opposite will be correct, use "sealed" always and if needed remove it. See this thread http://stackoverflow.com/questions/123773/is-oop-completely-avoiding-implementation-inheritance-possible#124591
OscarRyz
2008-09-30 21:15:21
There are a lot of ways to "reuse" a class besides sub-classing.
Jonathan Allen
2008-10-04 12:17:59
A:
The sealed keyword would work, but still you can derive from the class using reflection IIRC.
dalle
2008-09-30 20:36:15
you can also access private members with reflection. doesnt mean its a good idea
Kilhoffer
2008-09-30 20:43:32
I highly doubt that you can derive from the class using reflection, either. If someone shows me a class deriving from System.String, I'll believe it - but until then...
Jon Skeet
2008-09-30 20:52:39
Inherit via reflection? I don't even see how that would work or that the CLR would pay any attention even if you tried. Can you expand on that claim?
Robert Paulson
2008-09-30 20:53:24
A:
The sealed modifier will do what final does in Java.
Also, although this probably isn't what you're looking for in this situation, marking a class as static also keeps it from being inherited (it becomes sealed behind the scenes).
Max Schmeling
2008-09-30 23:19:56