[Arp] Difference between Value Objects and Models?

[Keith Salisbury]

Hey Grant,

I wasnt suggesting that we should go round telling people their doing
things wrong, but that said, as Rich has mentioned, precise
terminology is something very crucial especially in the early days
adopting a new technology.

Correct terminology is crucial in all programming, to ensure the
semantics are maintained correctly, and people are able to grasp the
concepts quickly and thoroughly.

I understand and agree with your distinction between the two types
VO/TO, however i do think thats only really the larger scale
applications where people would be "wrapping up" their VO's inside
TO's - i mean if you were to do that in the Aral's trunk version of
Arp3 for the Pizza example, to me, it would seem like overkill,
violating your KISS principal which i wholeheartedly agree with.

Its an area that, certainly for a learner Arper's, represents some
abiguity. Similarly the structure and contents of the models, and the
boundaries of the roles of controllers appear to suffer the same lack
of clarity.

keith


On 3/16/06, Davies, Grant M. <grant.davies at nscorp.com> wrote:
> I think you are all getting caught up in terminology..
>
> A Value object can be a domain object, a value object can be a transfer
> object. A value object can be a wrapper object, at least ValueObject has
> been an accepted design pattern that everyone has been using for a long time
> for the correct purpose, why try and invent/add yet another term or tell
> people "value object" is wrong, or say "hey they are not value objects, they
> are transfer objects".
>
> As long as you are using them in the correct way I don't believe ValueObject
> is a bad thing and I think a good practice is KISS (Keep it simple stupid).
>
> To me transfer objects are the wrappers and value objects contain data, but
> I don't think it's a big deal to call them both ValueObjects and I'm not
> going to tell someone they are doing it wrong by calling a "transfer object"
> a value object.
>
> Grant
>