Question

I have following piece of code:

class A
{
    public C GetC()
    {
        return new C();
    }
}

class B
{
    //has access to A but can not create C. Must ask A to create C.
    private void method()
    {
        A a = new A();
        C c = a.GetC();//Ok!
        C c2 = new C();//Not allowed.
    }
}

class C
{

}

What access modifiers should be used on C so it is ONLY accessible through A? (only class A knows how to properly initialize class C)
Or is there a better solution?

Answer 1

If you make A a nested class in C it should work.

public class B
{
    //has access to A but can not create C. Must ask A to create C.
    private void method()
    {
        var a = new C.A();
        var c = a.GetC();//Ok!
        var c2 = new C();//Not allowed.
    }
}

public class C
{
    private C()
    {
    }

    public class A
    {
        public C GetC()
        {
            return new C();
        }
    }
}