Στις 29/9/2013 2:04 μμ, ο/η Jussi Piitulainen έγραψε:
Steven D'Aprano writes:
On Sun, 29 Sep 2013 12:35:17 +0300, Jussi Piitulainen wrote:
try:
...
except socket.gaierror as e:
# watch out, a composition of bad advice (on demand) city, host = (
('city' in locals() or "blabla"),
('host' in locals() or "blablabla") )
Bad advice, and buggy as well.
py> city = "New New York"
py> ('city' in locals() or "Blah blah")
True
Oh man, can you imagine Nikos trying to debug that?
Thanks. Sorry. This hurts. I didn't mean it to be buggy.
Let's see. The task is to assign a default value to city and host, if
they haven't a value yet; on one line (which I take to mean one
statement); in an "except" block where we may not know which
assignment failed in the "try" block; without "if"; but "or" is
allowed.
But the logic I was trying to implement is
city, host = ( (city if 'city' in locals() else "default city"),
(host if 'host' in locals() else "default host") )
which uses an "if". The old tricks of using "or" and stuff for this
would surely go too far.
I know!
city, host = ( locals().get('city', "default city"),
locals().get('host', "default host") )
I tend to like this: I might use it because it is a clear way to tell
what var failed in the try clause and default it to soemthing.
Testing if the variables only exists when actually assigned:
>>> def foo(x, y):
... if x: foo = None
... if y: bar = "bar"
... return locals()
...
>>> foo(False, False)
{'y': False, 'x': False}
>>> foo(False, True)
{'y': True, 'x': False, 'bar': 'bar'}
Seems so.
What a monster, though. I don't even want to know if this, too, is
buggy in some way. It looks fragile.
Nikos, don't do this. The way to test if an assignment failed is to
use a try-catch. The way to know which one failed is to put each in
its own try-catch.
Dave's way though seems better.
Assign the vars default string and if they get re-assinged correctly
that would be ideal, otherwise we have already given them the defaults.
ipval = ( os.environ.get('HTTP_CF_CONNECTING_IP') or
os.environ.get('REMOTE_ADDR', "Cannot Resolve") )
city = "Άγνωστη Πόλη"
host = "Άγνωστη Προέλευση"
try:
gi = pygeoip.GeoIP('/usr/local/share/GeoIPCity.dat')
city = gi.time_zone_by_addr( ipval )
host = socket.gethostbyaddr( ipval ) [0]
except Exception as e:
print( "metrites.py => (%s): " % lastvisit, repr( sys.exc_info() ),
file=open('/tmp/err.out', 'w') )
I'll think i'll stick to this solution.
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