On Mon, Jan 14, 2013 at 01:32:07PM -0500, Tres Seaver wrote:
> While working on preparation for a Py3k port, I've stumbled across a
> fundamental issue with how ZODB structures its API. Do we intend that
> client code do the following::
>
> from ZDOB import DB, FileStorage
> db = DB(FileStorage('/path/to/Data.fs'))
ZODB.FileStorage is a module, you can't call it.
ZODB.DB, much to my surprise, refers to the ZODB.DB.DB class. A
backwards compatibility thing maybe?
> or use the module as a facade ::
>
> import ZODB
> db = ZODB.DB(ZODB.FileStorage.FileStorage('/path/to/Data.fs'))
This rings warning bells in my mind: if you're using the
ZODB.FileStorage module, you should import it directly:
import ZODB
import ZODB.FileStorage
db = ZODB.DB(ZODB.FileStorage.FileStorage('/path/to/Data.fs'))
> I would actually prefer that clients explicitly import the intermediate
> modules::
>
> from ZDOB import DB, FileStorage
> db = DB.DB(FileStorage.FileStorage('/path/to/Data.fs'))
(I'm not a fan of this style, but never mind that.)
> or even better::
>
> from ZDOB.DB import DB
> # This one can even be ambiguous now
> from ZODB.FileStorage import FileStorage
> db = DB(FileStorage('/path/to/Data.fs'))
This is what I usually do.
I don't get the ambiguous comment. ZODB.DB is (currently) always the
class[1]. ZODB.FileStorage is always the module.
[1] I think (currently) the only way to refer to the ZODB.DB module is
to use sys.modules['ZODB.DB']:
>>> import ZODB
>>> ZODB.DB
<class 'ZODB.DB.DB'>
>>> from ZODB import DB
>>> DB
<class 'ZODB.DB.DB'>
>>> import ZODB.DB
>>> ZODB.DB
<class 'ZODB.DB.DB'>
> The driver for the question is getting the tests to pass under both
> 'nosetests' and 'setup.py test', where the order of module imports etc.
> can make the ambiguous cases problematic. It would be a good time to do
> whatever BBB stuff we need to (I would guess figuring out how to emit
> deprecation warnings for whichever variants) before releasing 4.0.0.
Can you demonstrate the ambiguity? As I've shown before, I was unable
to find it, at least with Python 2.x.
Marius Gedminas
--
We don't really understand it, so we'll give it to the programmers.
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