On Thu, Mar 5, 2009 at 1:36 PM, Greg Ewing <greg.ew...@canterbury.ac.nz> wrote: > Guido van Rossum wrote: > >> This was a bad idea (*), and I'd be happy to ban it -- but we'd >> probably have to bump the pickle protocol version in order to maintain >> backwards compatibility. > > If you're talking about multiple calls to dump() on the same > pickler, it might be a bad idea for a network connection, but > I don't see anything wrong with using it on a file, and I find > it useful to do so sometimes. Banning it would be excessive, IMO.
I don't think I was thinking of that when I first designed pickle but the use case makes some sense. I still wish we could ban it or somehow make it *not* the default behavior; the bug in the App Engine bug I referenced before was introduced by an experienced developer who wasn't aware of this behavior and was simply trying to avoid unnecessarily creating a new pickler for each call. >> The exposition is unintentional but for historic reasons we can't just >> remove it. :-( > > A compromise might be to provide a memo attribute that returns > a wrapper around the underlying cache -- maybe with only a > clear() method if that's all you want to support. Then it'd be better to have a method clear_memo() on pickle objects. Perhaps we should do the opposite, and have a separate API for reuse *without* clearing the memo? <pickler>.dump_reusing_memo(<value>) and <unpickler>.load_reusing_memo(). -- --Guido van Rossum (home page: http://www.python.org/~guido/) _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
