[Twisted-Python] twisted.persisted.journal: a prevayler-inspired persistence system

Glyph Lefkowitz glyph at twistedmatrix.com
Sun Oct 13 02:26:52 EDT 2002

On Sat, 12 Oct 2002 22:17:21 -0400, Itamar Shtull-Trauring <twisted at itamarst.org> wrote:

> I've just checked in Journal, a persistence system inspired by Prevayler
> (http://www.prevayler.org for details). The idea is basically that all
> interactions with the system are done via serializable commands objects,
> which are logged *before* they execute. This allows us to keep down number of
> transactions in the system since in the worst case, the system can be
> restored by running the logged commands.

Seems like it would be pretty easy to create persistently-loggable objects for
non-deterministic events (like the "time", and "random" modules) in Python.  In
order to do that you'd need to modify your implementation to provide a default
"Command" base class so that non-deterministic events could be logged
automatically as sub-events.  Any reason that you wouldn't want to do that?
(If you don't want to pollute client code with inheritance, the default
implementation could just have a reference to a delegate ICommmand

 |    <`'>    |  Glyph Lefkowitz: Travelling Sorcerer  |
 |   < _/ >   |  Lead Developer,  the Twisted project  |
 |  < ___/ >  |      http://www.twistedmatrix.com      |
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