Re: Core Data Abstractions
Re: Core Data Abstractions
- Subject: Re: Core Data Abstractions
- From: T Reaves <email@hidden>
- Date: Mon, 30 May 2005 18:35:34 -0400
On May 30, 2005, at 2:02 PM, mmalcolm crawford wrote:
On May 30, 2005, at 9:00 AM, Vincent Coetzee wrote:
This is a problem that occurs often when using O/R mapping
frameworks or even object databases. In the ODBMS world we have a
pattern that we use to handle this, we call it the "manager
pattern". We create a single object called for example a
ProjectFactory or a ProjectManager, we then hide all of the code
in this object and we use a series of methods to gain access to
the objects we require such as
array = [ProjectFactory allProjects]
we may even have more specific methods for retrieving only the
names (often required for GUIs)
arrayOfStrings = [ProjectFactory allProjectNames];
The analogue here would be to create another entity to which all
the Projects are related. You then "fetch" the Projects simply by
following the relationship.
Whereas this would work, it's a nasty hack just to retrieve an
extent (all instances of a particular class). Wanting a class extent
is a fairly common thing, and needing to create and manage
collections manually to help is tedious at best.
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