recreate instance in base class

Question

Hi all, I was wondering if it is possible to change the type of an instance of a derived class in it's base class to another derived class from the same base . following I will try to explain it in a code .

public class ValueTypeClass
        {
            private string _Note;
            private String _Name;
            private nodeClass refrenceNode ;
    //...
            }

public class refrenceDBClass : valuetypeclass
{
//...
}

public class refrenceFileClass : valuetypeclass
{
//...
}

now each time the refrenceNode is changed I want to change the type of the instance based on the refrenceNode properties

Edit 1 : Now I'm doing this by having another class which keeps the detail of refrencedbclass and refrencefileclass and everytime the refrencenode is changed I'm creating a new instance .

public class ValueTypeClass
            {
                private string _Note;
                private String _Name;
                private nodeClass refrenceNode ;
                private detailClass detailInfo ;
        //...
                }


public class detailClass
{
//...
}
    public class refrenceDBClass : detailClass
    {
    //...
    }

    public class refrenceFileClass : detailClass
    {
    //...
    }

Answer 1

In C#, an instance never changes its type.

I don't understand the problem you want to solve with this, but I assume that you should aggregate this type you want to change, and create a new instance if some value changes. Like the strategy pattern, for instance.

Answer 2

You can not change the type of a managed .NET object. If you were encapsulating the object (in a wrapper - for example refrenceNode) you could swap the reference, but that is about it.

In some (limited) cases, you might be able to serialize/deserialize an encapsulated instance, changing the type in the process (only works for contract-based serializers, with compatible contracts; very unlikely). You certainly can't change the type of the current instance.

---

Re the edit; again, you can't change the type of how you expose the details, but with some casting you could make it work; vaguely, something like:

public class ValueTypeClass
{
    private string _Note;
    private String _Name;
    private nodeClass refrenceNode;
    public nodeClass ReferenceNode {
        get {return refrenceNode;}
        set {
            if(refrenceNode == value) return; // nop
            refrenceNode = value;
            BuildDetailInfo();
        }
    }
    private detailClass detailInfo;
    public detailClass DetailInfo {get {return detailInfo;}}
    private void BuildDetailInfo() {
        // TODO: decide on the appropriate type (based on refrenceNode)
        // and recreate detailInfo
    }
}

It sounds like you should also be making use of polymorphism. If you are doing data-binding there are some other things you can do (with considerable effort) to make this more friendly, but it won't affect regular code.