Default scope of variables
frank at chagford.com
Wed Jul 10 07:54:22 CEST 2013
"Ian Kelly" <ian.g.kelly at gmail.com> wrote in message
news:CALwzidnf3Obe0eNf3xTHLj5a40K8HxVThVEipECQ8+34ZxyLxw at mail.gmail.com...
> On Tue, Jul 9, 2013 at 10:07 AM, Ethan Furman <ethan at stoneleaf.us> wrote:
>> You could also do it like this:
>> def updating(self):
>> self.transaction_active = True
>> return self
> Yes, that would be simpler. I was all set to point out why this
> doesn't work, and then I noticed that the location of the
> "transaction_active" attribute is not consistent in the original code.
> The DbSession class places it on self, and then the example usage
> places it on the connection object (which I had based my version on).
> Since that seems to be a source of confusion, it demonstrates another
> reason why factoring this out is a good thing.
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
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?
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