[ZODB-Dev] ZODB _v_ attributes are tricky

[Dieter Maurer]

Kapil Thangavelu wrote at 2004-4-4 20:43 -0400:
> ...
>>   3. attributes that are garanteed to disappear at the next
>>      transaction boundary (do we need to control which
>>      type of transaction boundary?)
>> 
>>      do we need this type? for what use case?
>>
>> 
>>   4. attributes that live precisely for the current request
>> 
>>      used for things like "_v_skininfo".
>
>i think 3 and 4 are similiar enough that they can be merged into one, ie
>a transactional attribute, some computation, as zodb is not request
>bound, ie has no notion of such, it would be better imo to tie it in at
>the transaction level.

But, it would make usage such as "_v_skininfo" unrealiable.

  "_v_skininfo" (as it is implemented today) requires that the information
  remains during the complete request. If an application
  calls "get_transaction().commit|abort()" during request
  processing, this usage were no longer safe.

  This happens regulary when an exception occurs before
  error handling. "_v_skininfo" might not be defined
  for error handling (and the wrong "standard_error_message" might
  be found).


-- 
Dieter