Protected Class In C#

Question

This compiles well for me - However other people on a different thread are saying that protected classes cannot be declared in c# at top level

Is that the case?

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    protected class CsvReader
    {
    }
}

Answer 1

It doesn't compile for me with either VS2008SP1 or VS2010 (using csc.exe from the command line in both cases).

Which compiler are you using?

From section 3.5.1 of the C# specification:

• Types declared in compilation units or namespaces can have public or internal declared accessibility and default to internal declared accessibility.
• Class members can have any of the five kinds of declared accessibility and default to private declared accessibility. (Note that a type declared as a member of a class can have any of the five kinds of declared accessibility, whereas a type declared as a member of a namespace can have only public or internal declared accessibility.)

Answer 2

Consider: what would protected even mean on a top-level class. On a class member, it means that the member can be accessed by derived classes. But there's no such thing as a derived namespace, so what would protected even refer to?

Answer 3

I don't know if it compiles or not, but ask yourself this: what would this mean? It would seem to indicate that CsvReader could only be accessed from within the ConsoleApplication1 namespace, or any derived namespaces (?) ; but obviously this is nonsense. That's why it's not permitted in the spec. (At least that would be my explanation.)

Answer 4

Classes cannot be declared as protected at top level becuase then no code would be able to access it (unless inherited but then you should use abstract classes). Why create code that cannot be accessed?