[ZODB-Dev] ZODB _v_ attributes are tricky

[Dieter Maurer]

Shane Hathaway wrote at 2004-4-2 11:48 -0500:
> ...
>Instead, ZODB ought 
>to provide two kinds of documented descriptors: Volatile and 
>TransactionalVolatile.  Volatile attributes revert to the default state 
>at any time; TransactionalVolatile attributes reliably revert to the 
>default state upon commit or rollback (including savepoint commit or 
>rollback).

I fear, we need more kinds:

  1. attributes that can disappear at any time

     used for caching


  2. attributes that can disappear only at main transaction boundaries
     (but are not garanteed to disappear at the next boundary)

     used for caching of objects that are transactional aware
     such as database connections

  
  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".

-- 
Dieter