Re: Intersystems Caché
Re: Intersystems Caché
- Subject: Re: Intersystems Caché
- From: Art Isbell <email@hidden>
- Date: Mon, 10 Feb 2003 17:08:51 -1000
On Sunday, February 9, 2003, at 11:02 PM, Erik Ableson wrote:
I can see some overlap between the functionality in their built-in
object modelling capabilities and Enterprise Objects but I'm thinking
that the two together could make for some drastic simplification of
the development process. Particularly if the projected classes created
by Cachi will let me skip all of the fuss and bother about editing
contexts and just let me manipulate the classes directly.
An editing context determines what DB changes must be made when
changes are saved. So dispensing with an editing context means that
you would need to drop down to EOF's Access level in which fetched rows
populate NSDictionaries rather than EO's and SQL generation must be
managed by you. This is the way database programming has been done in
the past and makes life much more difficult.
OTOH, using the SQL interfaces via EOModeler has my head hurting about
how to go about defining an Enterprise object that contains other
objects...
Using EOF, you should not think about SQL. In the O-O world, an
object contains another object by defining an instance variable of the
type of the contained object. This translates to a to-one relationship
in the Entity-Relationship-Attribute (ERA) world. If an object
contains multiple objects of the same time, in the O-O world an array
instance variable is defined. This translates to a to-many
relationship in the ERA world.
Art
http://homepage.mac.com/aisbell/
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