Object identity changes while implementing restriction method?!

From: Julia (NoOne_at_Home.com)
Date: 04/30/04 

Date: Fri, 30 Apr 2004 13:11:44 +0200

Hi,

I am in process of writing an object model which being persisted into a
relational data base
and I want to add a RESTRICTION method which return a sub collection of
objects

for example,assuming I have the following table:

PERSONS

And the following class:

class Person
{
  Public Property Get Parent() as Persons 'Weak reference to the parent
collection
}

And hopefully the ability to write something like this:

Dim Persons as Persons
Dim Childrens as Persons
Dim Person as Person

Set Persons=Application.Persons 'All persons
Set Childrens=Persons.Restrict("age<18") ' Subset of persons

as far as I understand,since the Person object support the 'Parent' property
it's identity
compose of a row identity and the 'context'(the parent) in which it was
created.
In such case I need to hold more that one object for the same row?!

What is the solution for such a problem?

Assuming I agree to hold several objects for a row, is it good idea to make
all in memory objects
(which represent the same row) up to date?
meaning if one object state is change should I change all other object state
as well?

In such way i can preserve the correctness of a row representation *
(if one object saved to a data base other will reflects the current row
state as well, without the need
of reloading the row)
While keeping the difference of the context(the parant) for each object.

Thanks,

* assuming no changes to fields made by external process(calculated,trigger
etc...)

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