Question

I have a class library project. In this project i have some folders to seperate the logic.

Lets say i have a DAL library and within DAL i have IDAL, DALFactory and SQLServerDAL.
Now when i give DAL dll to an other programmer, he can use all of the subDlls. Suppose that i dont want him to use SQLServerDal but others. How can i encapsulate SQLServerDAL so that noone can realize it exists.

Thanks.
EDIT:
More spesically:

using DAL; // it can be written
using DAL.IDAL; // it can be written
using DAL.DALFactory; // it can be written
using DAL.SQLServerDAL; // it dont want to allow anyone write that

Answer 1

This is impossible to do with namespaces, because they don’t exist on the metadata level. Either make all classes in namespace SQLServerDAL internal, as suggested by others, or make SQLServerDAL a static internal class instead of a namespace. In this approach classes inside SQLServerDAL will become nested classes, and will be inaccessible from outside your DAL assembly:

// what you have now:
namespace DAL.SQLServerDal
{
    public class A {}
    public class B {}
}

// in other assembly
using DAL.SQLServerDal ; // ok
new A () ; // ok

// with internal classes:
namespace DAL.SQLServerDal
{
    internal class A {}
    internal class B {}
}

// in other assembly
using DAL.SQLServerDal ; // ok
new A () ;               // error: A is inaccessible due to protection level

// what I propose:
namespace DAL
{
    internal static class SQLServerDal
    {
        public class A {}
        public class B {}
    }
}

// in other assembly
using DAL.SQLServerDal ; // error: namespace DAL.SQLServerDal does not exist

However, if you use reflection or code generation, you may have problems if the libraries you are using do not support nested classes properly.