[Python-Dev] (try-except) conditional expression similar to (if-else) conditional (PEP 308)
python at rcn.com
Thu Aug 6 02:59:44 CEST 2009
[Jeffrey E. McAninch, PhD]
> I very often want something like a try-except conditional expression similar
> to the if-else conditional.
> An example of the proposed syntax might be:
> x = float(string) except float('nan')
> or possibly
> x = float(string) except ValueError float('nan')
I've long wanted something like this.
One possible spelling is:
x = float(string) except ValueError else float('nan')
If accepted, this would also solve the feature requests for various functions to have default arguments.
x = min(seq) except ValueError else 0 # default to zero for empty sequences
It would also be helpful in calculations that have algebraic restrictions:
sample_std_deviation = sqrt(sum(x - mu for x in seq) / (len(seq)-1)) except ZeroDivisionError else float('Inf')
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