My Class Diagram Problem

Suppose I have a class named A. This class has a attribute which is a class itself, but it maybe various classes, sometimes B1,sometimes B2 and �.
So,I thought the best model might be like this:
[img]http://www.freeimagehosting.net/uploads/cf4cb464ac.jpg" border="0" />[/img]
It�s good, because if another class like B3 needed to be added, It�s simple just inherit it from C class.
But the subject is B1, B2 and B3 are not type of C naturally .So what is problem?
Suppose we have similar situation for Z class. it has a attribute which is a class, and might be various class, sometimes B1,Sometimes D1,�..Like this:
[img]http://www.freeimagehosting.net/uploads/0d7c3aadf9.jpg" border="0" />[/img]
It means B1 is inherited from C and E.
Here we have 2 problems:
1-I had to model multi inheritance, that not supporting in my implementing environment and I have to use trick and pattern to do it, and it made more complex.
2-when I want to convert my class diagram to Data model:
I will have a C table with CID for Primary key. And I have B1 and B2 tables too. Related class of them inherited from C class, and then CID is primary key for B1 and B2 tables too.
This story goes for E table and, B1 and D1 Tables too. But in this case B1 table have 2 primaries key CID and EID.

What should I do?

What is the purpose of the model you are doing?

Hi Elham,

2-when I want to convert my class diagram to Data model:
I will have a C table with CID for Primary key. And I have B1 and B2 tables too. Related class of them inherited from C class, and then CID is primary key for B1 and B2 tables too.
This story goes for E table and, B1 and D1 Tables too. But in this case B1 table have 2 primaries key CID and EID.

I think, your solution 2 will be more complex then your suggested solution 1.

And For your solution 1, which pattern you are talking about??? I don't know any pattern which is intended for multiple inheritance problem..

And i think, there is more simple and more robust solution to this, interface.

Use interface.

Cheers,
Nachiket

Dear Nachiket,
1 and 2 are not my solutions! they are problems of my solution
[ December 22, 2008: Message edited by: Elham Ghaf ]

Hi,
Again what is the purpose of this model? why do you want to use inheritance ? what about interfaces so you can decouple the classes.

Would be great if you can brief out why A is a class, why B1 and B2 are part of it at times? Why Z is Z and not X or Y? why there is inheritance expected between E and B1, between E and D1?

Originally posted by Elham Gh:
... 1 and 2 are not my solutions! they are problems of my solution

[ December 22, 2008: Message edited by: Elham Ghaf ]

Class Diagrams are designed to model a problem after analysis, and then derive solutions. I personally feel you are modeling a solution (with no base)and deriving problems from it.

Originally posted by Akhilesh Trivedi:

Class Diagrams are designed to model a problem after analysis, and then derive solutions.

Actually, all they are designed to do is modeling classes and their relationships. There is a myriad of different ways to put them to good use.

Thank you for correcting me. Did I overlook "class" diagrams as "uml" diagrams?

Originally posted by Ilja Preuss:

...There is a myriad of different ways to put them to good use.

You mean code generators?

Originally posted by Akhilesh Trivedi:

You mean code generators?

That's just one froma thousands of ways.

Remember that the L in UML stands for "language". And it is nothing more than that - a tool for communication. You can use it to communicate many different things, for many different purposes, to many different people.

Just take a look at http://martinfowler.com/bliki/UmlMode.html for a start.

Thanks again, there is much more behind the sketches.