[Zope-dev] ZPatterns: SAVING doesn't tolerate missing attributes

[Steve Alexander]

Steve Spicklemire wrote:

> Hi Steve,
> 
>    Could you let some other value represent no car? (e.g., _.None?).
> 
> untested... 
> 
> WITH CompanyCars.getCar(self.car_id) or NOT_FOUND COMPUTE
>    car=RESULT,
>    car_registration=registration
> OTHERWISE LET
>    car=_.None
>    car_registration="no car"
> 
> WHEN OBJECT CHANGED CALL
>    HAS_CHANGED('car_id') and
>    (self.car_id and CompanyCars.getItem(self.car_id).decommission(),
>     ORIGINAL['car_id'] and (OLD['car'] and OLD['car'].commission()))
> SAVING car
> 
> Would that work?

Sure, that would work.

The workaround I've chosen is to use
   CompanyCars.getItem(ORIGINAL['car_id']).commission()
in place of
   OLD['car'].commission()

Oh, and I jsut noticed, I had commission and decommission the wrong way 
around in the example :-)

I'd still prefer SAVING to tolerate not-found attributes, though.

--
Steve Alexander
Software Engineer
Cat-Box limited
http://www.cat-box.net