[Python-Dev] PEP 409 and the stdlib

[Hrvoje Niksic]

On 05/21/2013 11:56 AM, Serhiy Storchaka wrote:
> try:
>       x = d['key']
> except KeyError:
>       x = fallback('key')
>
> def fallback(key):
>       if key not in a:
>           raise BusinessError(...)
>       return 1 / a[key] # possible TypeError, ZeroDivisionError, etc

Yes, in that case the exception will appear unintentional and you get 
the old message — it's on a best-effort basis.

Hrvoje