Business base inheritance

tchimev posted on Thursday, September 18, 2008

I'm trying to create an abstract class which inherits BB, like this:

    public abstract class Abstr<T> : BusinessBase<Abstr<T>>
    {
        protected static PropertyInfo<int> _id = RegisterProperty<int>(new PropertyInfo<int>("ID"));
        public int ID
        {
            get { return GetProperty<int>(_id); }
        }
    }

    public class Test : Abstr<Test>
    {
        private static PropertyInfo<string> _name = RegisterProperty<string>(new PropertyInfo<string>("Name"));
        public string Name
        {
            get { return GetProperty<string>(_name); }
            set { SetProperty<string>(_name, value); }
        }
    }


But when I create a new instance of type Test the ID property of the abstract class does not load with default value.
When I try to use the ID property I get an exception( something like RegisterProperty() func does not work correctly).
What am I missing?

ajj3085 replied on Thursday, September 18, 2008

Off the top of my head, shouldn't it be:
public abstract class Abstr<T> : BusinessBase<T>

tchimev replied on Thursday, September 18, 2008

may be like this

    public abstract class Abstr<T> : BusinessBase<T> where T : Abstr<T>

but that does not help
The error comes from the RegisterProperty() method.

tchimev replied on Thursday, September 18, 2008

Ok, I replaced my generics classes and it is working fine I think.

public abstract class Abstr : BusinessBase<Abstr>
{ }

public class Test : Abstr
{ }

But can someone explain why it is not working with generics?
thank you.

stefan replied on Friday, September 19, 2008

What you still need to implement is the 'dummy-workaround' as I call it.
Search the forum for '_dummy', especially in recent posts from Rocky.

In short:
If you have managed properties (e.g. using RegisterProperty) in any base classes,
then, in order to force RegisterProperty to be called in the right order (e.g. down-top),
you have to do the following in every base class using 'RegisterProperty:

- declare a static/shared dummy variable
    private static int _dummy;
    Private Shared _dummy As Integer

- initialize the dummy variable in the constructor
    protected MyClass() {
       _dummy = 0;
    }
    Protected Sub New()
       _dummy = 0
    End Sub

- override OnDeserialized, and initialize _dummy there too
    protected override void OnDeserialized(System.Runtime.Serialization.StreamingContext context) {
     base.OnDeserialized(context);
     _dummy = 0;
    }
    Protected Overrides Sub OnDeserialized(ByVal context As System.Runtime.Serialization.StreamingContext)
    MyBase.OnDeserialized(context)
    _dummy = 0
    End Sub

This is how I see it at the moment.


Stefan