Re: Queries and OO

From: Doc O'Leary (droleary.usenet_at_2005.subsume.com)
Date: 01/09/05 

Date: Sun, 09 Jan 2005 05:53:04 -0600

In article <1105187499.122160.231670@c13g2000cwb.googlegroups.com>,
 "frebe" <fredrik_bertilsson@passagen.se> wrote:

> After some debates at this forum I have made the conclusion that the
> concepts of queries does not exists within OO. The only *correct* way
> to find objects is through other objects (including collection
> objects).

Your conclusion makes no sense. You firstly don't define what exactly
you consider a query (let me assume you mean something like SQL), nor do
you say why a database table/row/column cannot be considered objects.
You can easily get the same kind of query ability if your OO environment
supports introspection (so you can refer to attributes) and uniquing
(i.e., a master record of all objects).

> If I have a number of "orders", I can find them by id if
> first I put them into a map using id as they key. If I want to get them
> ordered by "delivery data", I have to put them into a sorted set. If I
> want a list of "orders" that come from a given "customer", "customer"
> need to have a list of "orders" that belong to it.

What's your point? If you have a number of "orders", you can only find
them by id in a database if you first put them into a table. To get
them ordered by "delivery data" you have to specify their sort ordering.
If you want the orders for a specific customer, duh, you have to specify
that customer!

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