[Pythoncard-users] evaluating shelve module

shelve is one option we have for creating persistant data. ZODB is another.
We can't use something like anydbm, because the actual files created by
anydbm aren't portable across operating systems, only the source is
portable. Dan Shafer has started looking at shelve as described below. Those
of you interested in this area should share your findings on the list.

The shelve module is documented at:
http://www.python.org/doc/current/lib/module-shelve.html

There is an older tracker item for shelve as well:
http://sourceforge.net/tracker/index.php?func=detail&aid=442150&group_id=190
15&atid=369015

ka
---

Dan Shafer opened up a new tracker item on shelve:
http://sourceforge.net/tracker/?func=detail&atid=369015&aid=506564&group_id=
19015

Summary:
Looking at shelve
I had a chat with Kevin over the last day or two about
document models and decided to dive into the
development effort in a semi-modest way by looking
into persistent object stores for PythonCard.

The shelve stuff looks very straight-forward and
clean, so I'm going to take a first pass through a
couple of quick tests with it.

It is very transparent, fully cross-platform, and
handles any arbitrary Python object.

I'm not yet sure how this factors into or influences
the document model. I think I can make this pretty
transparent as long as we assume single-user stacks.
The shelve we create can be given the same name as the
stack/app transparently to the user.

My first step will be to take the Addresses stack and
switch it from a text file to a shelve for storage,
just to get my arms around the beast and to show two
different document models. Then I'll take one of my
old HyperCard stacks that makes more extensive use of
storage and give it a whirl.

A shelve can be _opened_ for read access by multiple
users but only the first one to open it gets write
privileges (like FileMaker at least used to be), and
there seems to be no way to control this (i.e.,
explicit role or privilege assignment). I think that's
perfectly acceptable, though, don't you?

Since I don't anticipate at this point that we'd even
expose this to a user, who would simply get automatic
data storage and retrieval a la HyperCard, I don't
think we need to wrapper anything.

Exploring it has been fun.

Dan