In what .NET languages can a class derive from its own nested class?

Question

In C#, trying to compile the following code yields an error, "Circular base class dependency involving 'A' and 'A.B'"

public class A : A.B
{
    public class B { }
}

However, I am looking at a 3rd party DLL via a decompiler, and seeing this structure. How is this possible? I can only assume the third party DLL was written in some other .Net language, but what language and what was the syntax?

Can you provide MSIL code from your decompiler? Is code you are decompiling was obfuscated? — Sergey Berezovskiy, Nov 30 '13 at 19:17
I would expect that no .NET language could do that. Here is a similar question on SO, not necessarily a duplicate from you though. http://stackoverflow.com/q/265585/809009 — Ondrej Janacek, Nov 30 '13 at 19:21
did this link can help you http://en.wikipedia.org/wiki/Multiple_inheritance — BRAHIM Kamel, Nov 30 '13 at 19:40
@edtheprogrammerguy that doesn't answer the question; it just says that the C# language prohibits it, which is something we already know. However, it's interesting to know that the CLI doesn't prohibit it. Also, that link has already been posted. — GregRos, Nov 30 '13 at 19:45
My hunch is that this is possible in C++/CLI. Many strange and evil things are possible there as well. — GregRos, Nov 30 '13 at 19:49
I think .NET 1.1 allowed this, and it got prohibited in 2.0 and above. Anyone have VS2002 or VS2003 hanging around to test it? — John Alexiou, Nov 30 '13 at 19:49
I would guess c++ or CIL itself. A nested class is just a matter of scope, there is no real problem to do this, its just silly... — AK_, Dec 01 '13 at 20:19
I've tried giving it a whack in unmanaged C++ and the compiler is complaining no matter what syntax I use. From the looks of things they've done some crazy jazz in CLI that is ill advised. Are you absolutely certain that's the structure you're seeing? — Pharap, Dec 03 '13 at 22:48
Is it possible that what you're experiencing is actually a situation similar to this: public class A { protected interface B { void doShizz(); } protected class C : A, B { void B.doShizz() { } } } — Pharap, Dec 03 '13 at 22:49

score 1 · Answer 1 · answered Dec 09 '13 at 09:28

1

It is because the dll you're trying to decompile is "obfuscated". the obfuscator change all the name of the classes so that decompilers cannot be decompiled.

answered Dec 09 '13 at 09:28

Pyisoe

26
2

score 0 · Answer 2 · answered Dec 04 '13 at 06:02

0

No DotNet language can do it. Deriving a child class indirectly from itself is wrong and can create circular dependancy. Think from the compiler's perspective, when it tries to compile class A, then first it needs to compile class B which is again dependent on class A and so on. So it creates a forever loop while compiling.

answered Dec 04 '13 at 06:02

Mayur Dhingra

1,527
10
27

1

B isn't derived from A, it's nested inside, which has nothing at all to do with the inheritance relationship. – Ben Voigt Dec 07 '13 at 00:44

In what .NET languages can a class derive from its own nested class?

2 Answers2