When I am using inheritance can I:
1.) use more than 1 base class

2.) when using the properties in the derived class can the variables be shared between 2 derived classes and 1 base class.

If anyone can show or thoroughly explain how these 2 situations can be done, it would make me understanding of vb.net object instantion a lot more clearer. I would really love a sample of a project with 2 derived classes using the same base class so I see how they are referenced between one another.

I bet this idea would really help alot of us beginners and intermediate developers the correct way to use inheritance.

Sincerely,

Ferd Krantz

F. Krantz

1. No. VB.NET supports only single inheritance

2. Not directly. Remember, the inherited class becomes part of the derived class. The instance of that class doesn't care that some of it is inherited. As with any two instances of any two objects- they talk through properties and methods. They can't share data directly. Like set a property in one and the other just changes. You would need to store the data outside of the object - like in a database or a session variable- for the data to be exchanged. You could also have the changed object call the other one and change the properties. But it's not something that just "happens".


Hal Levy
Web Developer, PDI Inc.

NOT a Wiley/Wrox Employee

Fred,

You actually can do this. It involves using class scope variables. Although this is really not a common practice it can be handy when you need to have a variable that should be applied to all instances of a class (or sub class). Take a look at this article for a more comprehensive explanation and some examples:
http://imar.spaanjaars.com/QuickDocID.aspx?QUICKDOC=272

Peter
-------------------------
Work smarter, not harder

See, I should stop answering technical questions :)

Hal Levy
Web Developer, PDI Inc.

NOT a Wiley/Wrox Employee

F. Krantz

I made a mistake and pressed the post button before responding, oops.

I just want to thank you for the help and would like to ask you if you have a simple shell of a multiple inheritance with a class and a inheritance with multiple forms that inherit.

I am studying the book Programming in VB.NET by Julia Bradley in a beginning VB.NET course.

I really like the idea of inheritance, unfortunately most books do not give complete information or don't show examples thoroughly so it is completely understood so there is no doubt in how to use it properly in future projects I design.

It is sad to see so many books with incomplete examples and poorly explained details needed to properly design OOP VB.net projects.

Keep up the fine forum,
Fred

F. Krantz

I figured out the solution to inheriting a form when using a base form. It is straight forward just remember to include at the top of the form the following.

import [form path]

class derived form
       inherits base form

That is it for inheriting another form as a base form, now use all the known key words for overriding the functions and sub's.

I thank everyone who has added to this forum, it was helpful to actually have a place to search for answers and experiment and get an answer I can actually understand and code easily.



F. Krantz