[Tutor] Error handling in functions / main program

Alan Gauld alan.gauld at blueyonder.co.uk
Thu Aug 12 22:48:46 CEST 2004

> 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.

That's a very profound question with no easy answer.
The C language takes the approach that the user checks 
the inputs before passing them - it leads to faster code.
Other languages tend to expect the function to do 
validation - very common in web page development and 
in financial apps in COBOL.!

Python has the tenet of its better to ask forgivness 
than permission, which tends to be interpreted as put 
the function code inside a try except and catch the 
possible erors. If the data is good there is minimal 
overhead, if its bad you pay the provce but still 
get a "safe" program. And of course the function 
can "raise" exceptions for the client program to catch.

So no clear cut answer, but maybe a hint.

Alan G.

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