Nested exceptions in Python

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Nested exceptions in Python

Archive - Originally posted on "The Horse's Mouth" - 2007-01-18 08:19:39 - Graham Ellis
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.