Question

I’m trying to provide two classes to my users – one that is read-only and one that is writable. The r/o will only have getters, while the writable will inherit from it and add the setters.

I was under the impression that C# should be able to handle it, but the compiler disagreed.
Why doesn’t this work? Any workarounds?

class A
{
    protected int m_val;
    public int Val
    {
        get { return m_val; }
    }
}

class B : A
{
    public int Val
    {
        set { m_val = value; }
    }
}

class Test
{
    static void Main(string[] args)
    {
        B b = new B();
        b.Val++; // <-- WHY DOESN'T THIS WORK?!
    }
}

P.S. the protected variable in the example above is artificial. My class actually wraps some native resources and the getting/setting happens on either const or mutable native pointer.

Answer 1

partial applies to a single type – not 2 types (A and B). You would need something more like below, ideally keeping the field private:

class A
{
    private int m_val;
    public int Val
    {
        get { return m_val; }
        protected set { m_val = value; }
    }
}

class B : A
{
    public new int Val
    {
        get { return base.Val;}
        set { base.Val = value; }
    }
}