[Python-Dev] a quit that actually quits

Thu Dec 29 04:18:59 CET 2005

Reinhold Birkenfeld wrote:
> Fredrik Lundh wrote:
>> Walter Dörwald wrote:
>>>>> We have sys.displayhook and sys.excepthook. Why not add a sys.inputhook?
>>> sys.inputhook gets passed each line entered and may return True if it has
>>> processed the line inself and False if normal handling of the input should be
>>> done. This allows special treatment of "quit", "exit", "help" /.../
>> so how would such a hook deal with the
>>>> >>> def exit():
>> ... pass
>> >>> exit
>>>> case ?
>> In the inputhook one would have to check for "exit" being defined at
> interpreter level.

Which is fairly trivial given a slight change to my proposed default input hook:
 def default_inputhook(statement):
 if statement in vars(sys.modules["__main__"]):
 return False
 try:
 aliased = sys.alias[statement]
 except KeyError:
 return False
 else:
 aliased()
 return True
That is, a real variable will always shadow an alias - you need to get rid of 
the real variable before the alias will start working again (or else change 
the name of the alias).
Or you can give the alias a different name via:
 sys.alias["exit_"] = sys.alias["exit"]
Cheers,
Nick.
-- 
Nick Coghlan | ncoghlan at gmail.com | Brisbane, Australia
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