Question

I have an abstract baseclass with some protected members, but no abstract members:

internal abstract class BaseClass
{

    protected readonly string Var1;
    protected readonly string Var2;

    protected BaseClass(string var1, string var2)
    {
        Var1 = var1;
        Var2 = var2;
    }

    protected int DoSomething1(string s)
    {
    }
}

And some classes that implements this baseclass and have some specific methods different for each one:

internal sealed class Child1:BaseClass
{
    internal Child1(string var1, string var2)
        : base(var1, var2)
    {
    }

    internal bool DomeSomethingSpecificForChild1(int i)
    {
    }

}

Now I have another class where I would like to have a variable of type BaseClass and depending of what I need, intantiate it with a child type.
But this isn’t working since the specific methods are not known.

public class MyClass
{
        private BaseClass myBaseClass;

    public bool DomeSomethingSpecific(int i)
    {
            myBaseClass = new Child1("a","b");
            myBaseClass.DomeSomethingSpecificForChild1(i);
    }
}

Is there a way I can accomplish what I want?
Or do I have to declare my variable in the inner scope of my method in MyClass?

public class MyClass
{
        private BaseClass myBaseClass;

    public bool DomeSomethingSpecific(int i)
    {
            var child1 = new Child1("a","b");
            myBaseClass.DomeSomethingSpecificForChild1(i);
    }
}

but this way I have no certainty that the class implements BaseClass.

An interface is not an option since I want it to stay internal, not public,
and I don’t want the baseclass to be instantiated, so I thought that abstract would be a good choice here..

Answer 1

private BaseClass child;

public bool DomeSomethingSpecific(int i)
{
        var c = {initialization to an instance - e.g. Child1(), Child2(), Child3()..};
        if (c is Child1){
            ((Child1)c).DomeSomethingSpecificForChild1(i);
        }
}