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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: Design of cross referring types/classes and proper usage of
 containers
Date: Tue, 04 Aug 2015 22:21:44 +0100
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Date: 2015-08-04T22:21:44+01:00
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Serge Robyns <serge.robyns@gmail.com> writes:

> Shall I Storing the full element of objects or references created
> through new T_xyz

The objects should be limited, in Ada terms; you don't want a copy of a
subscription in a client object (in general; I guess if subscriptions
have no other relationships .. well, no, a <thing that is subscribed to>
- say, Mailing_List - will in general have many subscribers, and a
client will have many subscriptions). In general I'd keep Clients as
elements in a Map keyed by client_ID, likewise Mailing_Lists. The
limited object in the Map *is* the Client, you can't copy it out and
risk confusing the copied info with the thing itself.

I'd try to implement a Subscription as a record containing a client_ID
and a mailing_list_ID and any supplementary data (renewal date, discount
rate ...), and keep them in a Subscription container (classic database
stuff). This does leave you to work out how to get efficient access from
a specific Client to all the Mailing_Lists that they subscribe to, and
vice versa, and you might want to optimise a bit.