[Tutor] Error handling in functions / main program

[Lloyd Kvam]

This is tough to answer and depends a lot on the context.  Different
folks are likely to give different responses.

My rules of thumb:

	User input NEVER causes a program failure.  try/except catches ALL
errors and provides a (hopefully) useful error message and a chance to
provide valid input.

	If the program fails in an unexpected area, report the failure and
exit.  This is likely to be a blanket try/except in main.  It does NOT
try to keep the program running, but simply provides a graceful
shutdown.  I like to email program traces back to me so that I can
quickly respond to problems.


I think that each try/except should be carefully programmed to deal with
EXPECTED errors.  A try/except that covers too much will likely do the
wrong thing when presented with the unexpected error.  My programs
usually have only a handful of try/except statements usually related to
user-input errors, network errors, and those fairly rare cases where
processing errors are expected and there is a reasonable recovery
strategy.


On Thu, 2004-08-12 at 11:09, Klas Marteleur wrote:

> ...and i am also planing to write a little GUI in another file
> -----------------------------------------------------------
> Now to my questions:
> How much and what type of error handling should be handled by:
> 1. The functions
> 2 The main program / GUI program.
> 
> I mean i could add a lot of extra error checking in the functions (... so that 
> correct inputs are used etc)? Or should that be the responsebility of the 
> main program to asure that the input to the functions are correct?
> Then what type of error handling should be located in the functions?
> -----------------------------------------------------------
> 
> I hope my questions wasnt to confusing (english is not my native language).
> 
> Kind regards
> Klas
> _______________________________________________
> Tutor maillist  -  Tutor at python.org
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Lloyd Kvam
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