Python: Catch exception and repeat code

Question

I have this code:

import imaplib, re
import os
import time

conn = imaplib.IMAP4_SSL("imap.gmail.com", 993)
conn.login("ddd", "dddd")

while(True):
        unreadCount = re.search("UNSEEN (\d+)", conn.status("INBOX", "(UNSEEN)")[1][0]).group(1)
        print unreadCount

        if int(unreadCount) > 10:
                print "restarting..."

        time.sleep(50)

Which sometimes loses the connection and stops working. How can I catch the exception and start the code over every time it breaks?

Thanks

Put a while loop with a try/except around the code beginning with conn = ..., and in the except block continue in your loop. Make sure you implement some max retries (e.g. while(retries<n)). BTW, I would put this as an answer but I've exceeded rep cap for the day already. I'll let someone else have the rep. — AJ.
– AJ., Commented Jun 21, 2011 at 19:25

mystery · Accepted Answer · 2011-06-21 19:26:29Z

4

import imaplib, re
import os
import time

while True:
    try:
        conn = imaplib.IMAP4_SSL("imap.gmail.com", 993)
        conn.login("ddd", "dddd")

        while True :
                unreadCount = re.search("UNSEEN (\d+)", conn.status("INBOX", "(UNSEEN)")[1][0]).group(1)
                print unreadCount

                if int(unreadCount) > 10:
                        print "restarting..."

                time.sleep(50)
    except HypotheticalException:
        pass

answered Jun 21, 2011 at 19:26

mystery

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2 Comments

AJ. Over a year ago

it's probably not desirable to have the outer loop run without bound. I would recommend a max retries value to control this.

X-Istence Over a year ago

@AJ: As most books generally say "That is left as an exercise to the reader"

dave · Accepted Answer · 2011-06-21 19:27:46Z

0

Use try ... except

try:
   unreadCount = re.search("UNSEEN (\d+)", conn.status("INBOX", "(UNSEEN)")[1][0]).group(1)
   if int(unreadCount) > 10:
            print "restarting..."

    time.sleep(50)
except Exception:
  pass

answered Jun 21, 2011 at 19:27

dave

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Comments

Spencer Rathbun · Accepted Answer · 2011-06-22 12:27:39Z

0

Try this:

import imaplib, re
import os
import time


for n in range(3):
try:
    conn = imaplib.IMAP4_SSL("imap.gmail.com", 993)
    conn.login("ddd", "dddd")
    while(True):
        unreadCount = re.search("UNSEEN (\d+)", conn.status("INBOX", "(UNSEEN)")[1][0]).group(1)
        print unreadCount

        if int(unreadCount) > 10:
            print "restarting..."

        time.sleep(50)
    break
except Exception, e:
    if n == 2:
        print >>sys.stderr, "Failure During processing, restarting..."
        print >>sys.stderr, e

You can set n to be however many tries you want to allow.

EDIT: Hmm, after further perusal, it seems I got your code slightly wrong. I've edited and fixed my version. You will need to adjust and edit your while loop, as I am not entirely sure what it is you are up to.

EDIT 2: Since you need to reconnect and try again, I've moved the conn section within the try block.

edited Jun 22, 2011 at 12:27

answered Jun 21, 2011 at 19:34

Spencer Rathbun

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3 Comments

donald Over a year ago

Allow you mean running the code again? I don't quite understand what+s the point of the "n".

Spencer Rathbun Over a year ago

The break will drop out of the for loop upon success. If you fail, n is checked. If it's less than 2, print the error and retry. Otherwise, quit trying.

donald Over a year ago

The "conn" must be inside the try, because I need to connect again if something is wrong.

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