How to retry after exception in python?

Question

Hi all,

I have a loop starting with for i in range(0, 100), and inside the loop, normally it would run correctly, but sometimes due to network conditions it would fail. Currently i have it set so that when failed, it would continue in except clause (continue on to the next number for i). I was wondering whether it is possible for me to reassign the same number to i and run through that the failed iteration of loop again.

Thanks a lot!

Jason

Answer 1

Do a while True inside your for loop, put your try code inside, and break from that while loop only when your code succeeds.

for i in range(0,100):
    while True:
        try:
            // do stuff
        except:
            continue
        break

Answer 2

The clearest way would be to explicitly set i. For example:

i = 0
while i < 100:
    try:
        # do stuff
        i += 1
    except MyException:
        continue

Answer 3

increment your loop variable only when the try clause succeeds

Answer 4

This question may be helpful: is there a pythonic way to try something up to a maximum number of times?

Answer 5

The more "functional" approach without using those ugly while loops:

def tryAgain(retries=0):
    if retries > 10: return
    try:
        # Do stuff
    except:
        retries+=1
        tryAgain(retries)

tryAgain()