[Zodb-checkins] CVS: ZODB3/ZODB - FileStorage.py:1.123
Fri, 13 Dec 2002 14:42:39 -0500
Update of /cvs-repository/ZODB3/ZODB
In directory cvs.zope.org:/tmp/cvs-serv15450
Update a comment about prev_txn
FileIterator.__len__(): Add this for Python 2.1 support.
=== ZODB3/ZODB/FileStorage.py 1.122 => 1.123 ===
--- ZODB3/ZODB/FileStorage.py:1.122 Tue Dec 10 16:40:45 2002
+++ ZODB3/ZODB/FileStorage.py Fri Dec 13 14:42:39 2002
@@ -775,8 +775,14 @@
# - data can be None, which indicates a George Bailey object
# (i.e. one who's creation has been transactionally undone).
- # If prev_txn is not None, it should contain the same data as
- # the argument data. If it does, write a backpointer to it.
+ # prev_txn is a backpointer. In the original database, it's possible
+ # that the data was actually living in a previous transaction. This
+ # can happen for transactional undo and other operations, and is used
+ # as a space saving optimization. Under some circumstances the
+ # prev_txn may not actually exist in the target database (i.e. self)
+ # for example, if it's been packed away. In that case, the prev_txn
+ # should be considered just a hint, and is ignored if the transaction
+ # doesn't exist.
if transaction is not self._transaction:
@@ -2215,6 +2221,11 @@
self._stop = stop
+ def __len__(self):
+ # This is a lie. It's here only for Python 2.1 support for
+ # list()-ifying these objects.
+ return 0
file = self._file