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[Python-ideas] a in x or in y

Andrew Barnert abarnert at yahoo.com
Thu Feb 13 05:41:25 CET 2014 
On Feb 12, 2014, at 15:55, Carl Meyer <carl at oddbird.net> wrote:

> On 02/12/2014 02:12 PM, Ram Rachum wrote:
>> What do you think about adding this to Python:
>> 
>>    'whatever a long string' in x or in y
>> 
>> I've often wished for this because the current way is quite verbose:
>> 
>>    'whatever a long string' in x or 'whatever a long string' in y

For future reference, using expression_with_side_effects() instead of 'whatever a long string' would be a more compelling use case. With a long string, it's inconvenient and ugly to repeat it; with an expression with side effects, it's all that plus incorrect to boot.

But of course the same solutions still work.

> Except you'd never actually do that, you'd just put the long string in a
> variable. Or the other option:
> 
>    any('whatever a long string' in i for i in [x, y])

Or, if you're doing this so often that even this is too verbose:

    def in_any(element, *containers):
        return any(element in container for container in containers)

    in_any('whatever a long string', x, y, z, w)

If you're not doing it often enough for in_any to become familiar, then you didn't have a problem to solve in the first place. :)
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