[cgma-dev] Observer question?

[Tim Tautges]

On 07/22/2013 04:20 PM, David Thompson wrote:
> Hi Tim,
>
>>> ... for tracking persistent geometry across operations ... Would you advise adding UUIDs as attributes ...?
>>
>> No; you'd get exactly the same results.  We hang an attribute on the engine entities pointing to the CGM entities, then after the operation, see what's left, and remove the CGM entities that are no longer referenced.  So in a sense, we only get "before" and "after" pictures, not "during" pictures.
>
>
> I think we're in violent agreement; if there is no "during" picture, then I should just fetch entities "after" which have the same entityId as they did "before." Is that what you meant?
>

Yep.  And, CGM should do that for you already.  That is, the CGM entities that survive will persist, and the others will 
have their observer functions called before they get deleted.

- tim

> 	Thanks,
> 	David
>

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              Tim Tautges            Argonne National Laboratory
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