[Tutor] UPDATE: Is there a 'hook' to capture all exits from a python program?

[Albert-Jan Roskam]

----------------------------
On Fri, Mar 20, 2015 10:37 AM CET Peter Otten wrote:

>Alan Gauld wrote:
>
>> On 20/03/15 02:57, Doug Basberg wrote:
>> 
>> Still, I would like to know if a 'hook' exists on exit from Python.  I am
>> running Linux on a Raspberry Pi with Python 2.7.4  I also run an Apache
>> server on the Pi for monitor and control of power, HVAC, and security.
>> 
>> Your previous mail got you three options. I'd use all of them!
>> 
>>  > > https://docs.python.org/3/library/atexit.html
>>  >
>>  > ... But that's only for normal program termination; sys.excepthook is
>>  > for unexpected exits
>> 
>> 
>> def close_relay(e=None,v=None,t=None):
>>     try:
>>        if not relay_closed()
>>           really_close_relay()
>>     except:
>>        really_close_relay()
>> 
>> import sys, atexit
>> atexit.register(close_relay)
>> sys.excepthook = close_relay
>> 
>> 
>> try:
>>     main program here
>> finally:
>>     close_relay()
>
>That reeks of cargo cult. Are there actual scenarios for each of the three 
>mechanisms where it is the only one that works?
>
>I would expect that
>
>try:
>    main program here
>finally:
>    close_relay()

Is this (also) called a diaper pattern? Or is that name reserved for the antipattern with try-bare except, where the 'except' catches all the sh*t (pardon my language)?


>provides the same level of confidence, i. e. the relay will be closed when 
>the program closes normally or the main code raises an exception, but not if 
>the process is killed.
>
>_______________________________________________
>Tutor maillist  -  Tutor at python.org
>To unsubscribe or change subscription options:
>https://mail.python.org/mailman/listinfo/tutor