In certain situations particularly when dealing with networks and distributed systems you'd want your program to retry certain a particular operation certain number of times in case it fails before giving up. For instance your program is trying to connect to a mail server which is due to network connectivity temporarily giving socket error.
The simple way is to put a loop, try certain number of times and if the result still fails give up. I found this pattern normal so I wrote a decorator in Python which can be generically used.
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def attempt_retries(func, retries=3, delay=3, IgnoreException=Exception): """ Decorator for ignoring certain exception for certain number of times and retrying with certain delay e.g. func = @retry(connect_imap, 10, 5, SocketError) # Tries ten times e.g.2. retry(connect_imap)(username, password) """ def dec(*args, **kwargs): for i in range(retries-1): try: return func(*args, **kwargs) except IgnoreException: sleep(delay) return func(*args, **kwargs) return dec
attempt_retries( server_connect, 10, 20, SocketError ) ( host, user, pass)
r_server_connect = attempt_retries( server_connect, 10, 50, SocketError ) r_server_connect( host, user, pass)