I generally use context managers for my SQL database connections, so I can just
write code like:
with psql_cursor() as cursor:
<do whatever>
And the context manager takes care of making a connection (or getting a
connection from a pool, more likely), and cleaning up after the fact (such as
putting the connection back in the pool), even if something goes wrong. Simple,
elegant, and works well.
The problem is that, from time to time, I can't get a connection, the result
being that cursor is None, and attempting to use it results in an
AttributeError. So my instinctive reaction is to wrap the potentially offending
code in a try block, such that if I get that AttributeError I can decide how I
want to handle the "no connection" case. This, of course, results in code like:
try:
with psql_cursor() as cursor:
<do whatever>
except AttributeError as e:
<handle no-connection case>
I could also wrap the code within the context manager in an if block checking
for if cursor is not None, but while perhaps a bit clearer as to the purpose,
now I've got an extra check that will not be needed most of the time (albeit a
quite inexpensive check).
The difficulty I have with either of these solutions, however, is that they
feel ugly to me - and wrapping the context manager in a try block almost seems
to defeat the purpose of the context manager in the first place - If I'm going
to be catching errors anyway, why not just do the cleanup there rather than
hiding it in the context manager?
Now don't get me wrong - neither of these issues is terribly significant to me.
I'll happily wrap all the context manager calls in a try block and move on with
life if that it in fact the best option. It's just my gut says "there should be
a better way", so I figured I'd ask: *is* there a better way? Perhaps some way
I could handle the error internally to the context manager, such that it just
dumps me back out? Of course, that might not work, given that I may need to do
something different *after* the context manager, depending on if I was able to
get a connection, but it's a thought. Options?
-----------------------------------------------
Israel Brewster
Systems Analyst II
Ravn Alaska
5245 Airport Industrial Rd
Fairbanks, AK 99709
(907) 450-7293
-----------------------------------------------
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