Re: Design Pattern for referential integrity

[Brian McCallister]

I generally do soemthing like:

class A
{
        Set bs;
        ...
        public void addB(B b)
        {
                ibs.add(b);
                if (! b.getAs().contains(this)) b.addA(this);
        }
}
-Brian

On Dec 15, 2003, at 6:03 PM, Tino Sch�llhorn wrote:

Hi there,

this is a topic which is not specifically bound to ojb - but since 
there are a lot of users out there who might have the same problem 
(and hopefully a solution) I post this message here:

I have several classes which I use to map tables to objects. Now I am 
wondering what the most appropriate design pattern for "referential 
integrity" is. An example. Suppose we have two classes which implement 
a N:M-Relation:

class A {
        Collection bs;
        
        void addB(B b) {
                bs.add(b);
        }
        void removeB(B b) {
                bs.remove(b);
        }
}
// the class B is the same as above.

Now I'd like to use these classes. But there is one problem: When 
using these simple classes I have to write:

A a = new A();
B b = new B();
a.addB(b);
b.addA(a);
so that one can navigate from both instances to each other. But I 
juest want to write:

a.addB(b);

And the changes should also be reflected in object b.

Does anyone know a design pattern for this (quite common) problem?

Tino



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