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January 18, 2007
Nested exceptions in Python
Yes, you can nest exceptions in Python - here's an example from yesterday's course.
I'm reading in lines from a data file and counting the numbe of occurrences of a particular series of events in a dictionary of dictionaries.
An exception is thrown if a counter doesn't already exist ... we'll catch that and create the extra counter if we have to ... excpet that ...
The incoming data line may be a short header, in which case we ignore it.
Here's the code:
import urllib
fh = urllib.urlopen("http://192.168.200.67/data/access_log.xyz")
counter = {}
goofs = 0
while 1:
line = fh.readline()
if not line: break
hinfo = line.split(" ")
try:
counter[hinfo[6]][hinfo[0]] += 1
except:
try:
counter[hinfo[6]] = {}
counter[hinfo[6]][hinfo[0]] = 1
except:
pass
print counter
print "problem count =",goofs
Remember that in Python, you inset code to indicate your block structure, and that the pass statement can be used to create a do-nothing block.
Posted by gje at January 18, 2007 08:19 AM