retry_decorator.py

# -*- coding: utf-8 -*-
from functools import wraps
import time

def retry(tries, exceptions=None, delay=0):
    """
    Decorator for retrying a function if exception occurs
        
    tries -- num tries 
    exceptions -- exceptions to catch
    delay -- wait between retries
    """
    exceptions_ = exceptions or (Exception, )
    def _retry(fn):
        @wraps(fn)
        def __retry(*args, **kwargs):
            for _ in xrange(tries+1):
                try:
                    return fn(*args, **kwargs)
                except exceptions_, e:
                    print "Retry, exception:" + str(e)
                    time.sleep(delay)
            #if no success after tries raise last exception
            raise
        return __retry
    return _retry

if __name__ == '__main__':
    @retry(1)
    def fail():
        raise Exception("Oh woe is me")

    @retry(42)
    def no_fail():
        print "I work"

    print "This will not fail"
    no_fail()

    print "--"
    print "The next test is going to fail"
    fail()

The script will produce this output when run:

This will not fail
I work
--
The next test is going to fail
Retry, exception:Oh woe is me
Retry, exception:Oh woe is me
Traceback (most recent call last):
  File "retry_decorator.py", line 42, in <module>
    fail()
  File "retry_decorator.py", line 19, in __retry
    return fn(*args, **kwargs)
  File "retry_decorator.py", line 31, in fail
    raise Exception("Oh woe is me")
Exception: Oh woe is me