Nrthugu

I've created 3 classes, A, B and C.

• B inherits from A


• C inherits a Collection of A

However, I can't understand why when inheriting from a collection, the derived class can access only the protected member of the base class.

public class A

{

    public int MyPublic { get; set; }

    protected int MyProtected { get; set; }

    internal int MyInternal { get; set; }

    protected internal int MyProtectedInternal { get; set; }

}

public class B : A

{

    B MyB { get; set; }

    B()

    {

        MyB.MyProtected++;

        MyB.MyInternal++;

        MyB.MyPublic++;

        MyB.MyProtectedInternal++;

    }

}

public class C : Collection<A>

{

    C MyC { get; set; }

    C()

    {

        MyC[0].MyProtected++; // Inaccessible due to its protection level.

        MyC[0].MyInternal++;

        MyC[0].MyPublic++;

        MyC[0].MyProtectedInternal++;

    }

}

Firstly, and probably not strictly relevant to your question, I'm not sure why C has a member MyC. Type C is a Collection<A> so you can just use the indexer this[int x] to access the collection items.

To give C access to ALL of the members of A while still limiting access for anything else, you could make C a nested type.

public class A

{

    protected int MyProtected { get; set; }

    private int MyPrivate { get; set; }



    public class C : Collection<A>

    {

        public void Foo()

        {

            this[0].MyProtected++; // Allowed

            this[0].MyPrivate++; // Also allowed!

        }

    }

}

Note that this gives C more access to A than you intended (all member regardless of access modifier).

Some discussion of pros/cons of nested classes here: What are reasons why one would want to use nested classes?

As mentioned in the comments, you aren't actually inheriting from A. You're inheriting from Collection<T>.

If your goal is to expose the protected properties of A, then make a class that inherits from A and make public properties of the same name that just modify the properties of the inherited class. Then make a collection of that new class.

Something like this. Notice the new class D:

public class D : A {

    new public int MyProtected {

        get {return base.MyProtected;}

        set { base.MyProtected = value; }

    }

    new public int MyProtectedInternal {

        get { return base.MyProtectedInternal; }

        set { base.MyProtectedInternal = value; }

    }

}

public class C : Collection<D>

{

    C MyC { get; set; }

    C()

    {

        MyC[0].MyProtected++;

        MyC[0].MyInternal++;

        MyC[0].MyPublic++;

        MyC[0].MyProtectedInternal++;

    }

}

The new modifier keyword indicates that you are replacing the property from the inherited type.