[Zope-dev] Re: [ZODB-Dev] Replacing bobobase_modification_time

[Casey Duncan]

On Tuesday 08 January 2002 09:15 am, Jim Fulton allegedly wrote:
>
> The basic problem is that b_m_t is a database modification time, not
> an application-meaningful time. You pointed out that there are
> application-meaningful times that are not captured by the database time.
> In addition, there are database modifications that are not meaningful
> to the application.  Operations like export/import (copy/paste),
> version commit/abort, transactional undo, etc. cause the database times
> to change without making application-meaningful changes.
>
> Also, there could be state changes in an object that are not meaningful
> to the application.
>
> I think that a much better approach, if modification time is important
> to your application, is to store the application modification time in the
> object as a data attribute.
>
> Jim

Do you think then that it might be reasonable to include such a service in a 
higher level Zope base class? It seems to me that creation and mod time are 
basic services that are needed in many applications.

I certainly agree with you as far as "database" vs. "application". It seems 
that it has been widely encouraged to use b_m_t for something that it was not 
designed for. Especially in light of the fact that it is a default 
index/metadata entry in ZCatalog. I think that developing an 
application-level service in Zope that behaves as people expect would prove 
extremely useful.

On that note I think a problem with doing that is the inevitable namespace 
pollution that occurs when attributes are added widely to objects across the 
system. Has any thought been given to creating a better naming standard for 
attributes so that it is easier to avoid collisions? Perhaps something like 
the "_p_" and "_v_" prefixes used now? Or even just prefixing them with 
"zope" (for "Zope level" attrs).

/---------------------------------------------------\
  Casey Duncan, Sr. Web Developer
  National Legal Aid and Defender Association
  c.duncan@nlada.org
\---------------------------------------------------/