On Thu, Jul 19, 2018 at 8:47 AM Rhodri James <rhodri@kynesim.co.uk> wrote:

On 19/07/18 09:33, Antoine Pitrou wrote:
> There is a use case I sympathize with: the argument-is-None case.  For
> that I would suggest a simpler form:  "A else B" which would evaluate
> to A if A is not None, otherwise to B (parentheses may be mandatory).
> 
> So e.g. one of the examples would read:
> 
>       def insort_right(a, x, lo=0, hi=None):
>           # ...
>           hi = hi else len(a)
>           # ...

Much as I would like a keyword, "else" is the wrong one.  It implies we 
are dealing with truthiness, which we aren't, and lays a subtle semantic 
trap as a consequence.

If anyone can think of a good word for "if it isn't None, otherwise", 
I'd be all for it :-)

-- 
Rhodri James *-* Kynesim Ltd
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I think that it may look better with the order switched and the word unless, as in

    def insort_right(a, x, lo=0 hi=None):

        # ...

        hi = len(a) unless hi

        # ...

Unfortunately, this does maybe feel more like checking for truthiness than non-Null value

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