Is there any way to manipulate variables passed in to a child class constructor before passing it off to the base class?

Question

Hi,

Is there any way to delay calling a superclass constructor so you can manipulate the variables first?

Eg.

public class ParentClass
{
   private int someVar;

   public ParentClass(int someVar)
   {
       this.someVar = someVar;
   }
}

public class ChildClass : ParentClass
{
    public ChildClass(int someVar) : base(someVar)
    {
        someVar = someVar + 1
    }
}

I want to be able to send the new value for someVar (someVar + 1) to the base class constructor rather than the one passed in to the ChildClass constructor. Is there any way to do this?

Thanks,
Matt

Answer 1

public class ChildClass : ParentClass
{
    public ChildClass(int someVar) : base(someVar + 1)
    {
    }
}

Now if this manipulation is more complicated than incrementing an integer and deserves a separate method, you could call this method inside base but this method needs to be static.

Answer 2

How about the something like this? You can have different implementations ISomething and pass the required to the base class.

public interface ISomething
{
    int DoSomething(int someVar);
}

public class Something : ISomething
{
    private int someVar;

    public Something(int someVar)
    {
        this.someVar = someVar;
    }

    public int DoSomething(int someVar)
    {
        return someVar + 1;
    }
}

public class ParentClass
{
   private int someVar;

   public ParentClass(ISomething something)
   {
       this.someVar = something.DoSomething(someVar);
   }
}

public class ChildClass : ParentClass
{
    public ChildClass(int someVar) : base(new Something(someVar))
    {

    }
}