Inheritance and modifiers

Question

Hello everyone, i'm having problems with inheritance and access modifiers.

Well, here's the interface code IParent:

internal interface IParent {
    void doStuff();
}

I have a class that implements the intercafe IParent, called Parent:

internal class Parent : IParent {
    public void doStuff() {
        // implementation
    }
}

The interface and class are restricted only the same assembly due to the internal modifier and this is my goal. But i have a class Child that override the method doStuff(). This class i want to be visible for other assemblies:

public class Child : Parent {
    public new void doStuff() {
        // more implementations
        base.doStuff();
    }
}

But the compiler does not accept. The erros says the class Child is less accessible then the class Parent. Well is that right? How to solve my problem? I can modifie the modifier of class Parent to public and call the method direct like:

new Parent().doStuff();

But it may give error! I want:

new Child().doStuff();

I took a test in Java and works! Only instead of internal modifier i use the default (no modifier) thats restricts access to package. Thaks!

Answer 1

You can't do this in C# -

Inheritance is a public contract - allowing this would basically be saying "The Child class is a specific form of [something I'm hiding from you]", which is not allowed (and somewhat confusing).

Typically, this situation can be handled via encapsulation instead of inheritance.  You can do something like:

public class Child
{
    public Child()
    {
        this.Parent = new Parent();
    }

    internal Parent Parent { get; private set; }


    public void DoStuff()
    {
       // Do your stuff...
       this.Parent.DoStuff();
    }
}

---

Reed Copsey, Jr. - http://reedcopsey.com
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Answer 2

You won't be able to do this.  You cannot have a public child if it's parent is hidden (to something outside of the assembly.

Answer 3

If you want to prevent the base class from being instantiated, you can make its constructor internal.