On Sat, 6 Mar 2010 04:13:49 pm Gil Cosson wrote:
> I have some code to perform an exponential backoff. I am interacting
> with a few different web services. Checking for a specific Exception
> and then re-invoking the failed call after waiting a bit. I don't
> want to code the backoff in ten different places. Really miss the C
> pre-processor.
>
> I am tempted to try something like the following, but I understand
> that eval should be a last resort.
>
> Any pythonic best practice for this situation?:
Functions are first-class objects that can be passed around as data. Use
them.
def check_some_website(url, x):
# whatever
def exponential_backoff(function, args, exception, numretries):
# Backoff 1 second, 2 seconds, 4 seconds, 8, 16, ...
t = 1
for i in xrange(numretries):
try:
return function(*args)
except exception:
time.sleep(t)
t *= 2
raise exception("no connection after %d attempts" % numretries)
result = exponential_backoff(check_some_website,
("http://example.com";, 42), HTTPError, 8)
Any time you think you need eval, you almost certainly don't.
--
Steven D'Aprano
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