"Ian Kelly" <ian.g.ke...@gmail.com> wrote in message news:calwzidk2+b5bym5b+xvtoz8lheyvhcos4v58f8z2o1jb6sa...@mail.gmail.com... > On Tue, Jul 9, 2013 at 11:54 PM, Frank Millman <fr...@chagford.com> wrote: >> You had me worried there for a moment, as that is obviously an error. >> >> Then I checked my actual code, and I find that I mis-transcribed it. It >> actually looks like this - >> >> with db_session as conn: >> db_session.transaction_active = True >> conn.cur.execute(...) >> >> I am still not quite sure what your objection is to this. It feels >> straightforward to me. >> >> Here is one possible answer. Whenever I want to commit a transaction I >> have >> to add the extra line. There is a danger that I could mis-spell >> 'transaction_active', in which case it would not raise an error, but >> would >> not commit the transaction, which could be a hard-to-trace bug. Using >> your >> approach, if I mis-spelled 'db_session.connect()', it would immediately >> raise an error. >> >> Is that your concern, or are there other issues? > > Yes, that is one concern. Another is that since you mistakenly typed > "conn" instead of "db_session" once, you might make the same mistake > again in actual code, with the same effect (unless the conn object > doesn't allow arbitrary attributes, which is a possibility). Another > is that the code adheres better to the DRY principle if you don't need > to copy that line all over the place.
Thanks to you and Ethan - that does make sense. I have reviewed my code base to see how many occurrences there are, and there are just three. All database objects inherit from a DbOject class. The class has a save() method and a delete() method. Each of these requires a commit, so I use my technique there. All database updates are activated by calling save() or delete(). I have an init.py script to 'bootstrap' a brand new installation, which requires populating an empty database with some basic structures up front. DbObject cannot be used here as the required plumbing is not in place, so I use my technique here as well. However, this does not invalidate your general point, so I will keep it in mind. Thanks Frank -- http://mail.python.org/mailman/listinfo/python-list
