Question

Is there a way in C# (4+) for the instance of class A (instanceOfClassA) in class B to access the variable x (as in SomeMethodInClassA) without x being public (see code example below)?

    class A
    {
    B linkToClassB;

    void SomeMethodInClassA()
    {
    linkToClassB.x = 1;
    }
    };

    class B
    {
    public int x; // This should be accessible from class A without being public

    A instanceOfClassA;
    ...
    };

I was wondering that because as instanceOfClassA is a member of of class B there might be a way to allow a class to access pecific methods of their member classes.

Answer 1

There are two options for A being able to access x without the classes being part of the same hierarchy:

Nested class

If A is a nested class inside B then A can access x:

class B {
    private int X;
    A instanceOfClassA;

    private class A {
        B linkToClassB;
        void SomeMethodInClassA() { linkToClassB.x = 1; }
    }
}

internal access

If the two classes are in the same assembly and x is be internal then it is possible for A to access it. Of course in this case it is possible to access x from all other classes in the same assembly as well, which might not be desirable.

class A
{
    B linkToClassB;

    void SomeMethodInClassA() { linkToClassB.x = 1; }
}

class B
{
    internal int x;
    A instanceOfClassA;
}