Re: How do I get EO's instantiated with dynamic class?
Re: How do I get EO's instantiated with dynamic class?
- Subject: Re: How do I get EO's instantiated with dynamic class?
- From: Riccardo De Menna <email@hidden>
- Date: Fri, 17 Aug 2007 18:48:15 +0200
Oh thank you Guido. I had used restricting qualifiers before in a
horizontal inheritance setup when I needed non-abstract superclasses
but I had not realized that in fact a single table inheritance was
exactly what I was asking for. I used to skip over that kind of
inheritance back when I read about it in the EOmodeler pdf cause it
looked "messy" in Apples example context. Now it suddenly makes
perfectly sense.
Not only... you also forced me to find out there was a contextual
menu with cool shortcuts in entity modeler ;-)
On 17.08.2007, at 10:20, Kieran Kelleher wrote:
I prefer using the Strategy Design Pattern instead of inheritance
whenever possible
About the strategy design pattern route suggested by Kieran... yes
please... send me some links.. I'm eager to look into it. A sort of
plugin scenario would also fit perfectly well and I would enjoy some
new design patterns to feed on.
Thanks again to you both for the help provided,
Cheers,
Ric
On 17/ago/07, at 18:06, Guido Neitzer wrote:
On 17.08.2007, at 09:46, Riccardo De Menna wrote:
I'm perfectly fine with one single table holding domain info... I
simply want to fetch from it and receive specific subclasses of
the main "domain" class.
It's called "Single Table Inheritance".
Create "Domain" Entity, make it static. Have an attribute
"topLevelDomain". Make a subclass of "Domain" with Single Table
Inheritance (it's an option in Entity Modeler), call it ComDomain
and set the qualifier to be "topLevelDomain = 'com'".
There you go. Whenever you query your database for "Domain"
objects, all domains with topLevelDomain = 'com' come back as
ComDomain objects.
You have one table and whatever number of Entities using it.
cug
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