Quick survey: locals in comprehensions (Python 3 only)

[Steven D'Aprano]

On Tue, 26 Jun 2018 12:04:16 +0200, Antoon Pardon wrote:

> On 26-06-18 11:22, Steven D'Aprano wrote:
>> On Tue, 26 Jun 2018 10:20:38 +0200, Antoon Pardon wrote:
>>
>>>> def test():
>>>>     a = 1
>>>>     b = 2
>>>>     result = [value for key, value in locals().items()] return result
>> [...]
>>
>>> I would expect an UnboundLocalError: local variable 'result'
>>> referenced before assignment.
>> Well, I did say that there's no right or wrong answers, but that
>> surprises me. Which line do you expect to fail, and why do you think
>> "result" is unbound?
> 
> I would expect the third statement to fail because IMO we call the
> locals function before result is bound. But result is a local variable
> so the locals function will try to reference it, hence the
> UnboundLocalError.

Ah, I see. Thanks for the explanation.

Given that locals() is capable of dealing with uninitialised local 
variables without raising, would you like to revise your expectation?



-- 
Steven D'Aprano
"Ever since I learned about confirmation bias, I've been seeing
it everywhere." -- Jon Ronson