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[Python-Dev] lambda (x, y):

Serhiy Storchaka storchaka at gmail.com
Sat Jan 25 07:55:04 CET 2014 
25.01.14 07:41, Greg Ewing написав(ла):
> Brett Cannon wrote:
>>
>> On Fri, Jan 24, 2014 at 10:50 AM, Ram Rachum <ram at rachum.com
>> <mailto:ram at rachum.com>> wrote:
>>
>>         lambda (x, y): whatever
>>
>> http://python.org/dev/peps/pep-3113/
>
> Part of the rationale in that PEP is that argument unpacking
> can always be replaced by an explicitly named argument and
> an unpacking assignment. No mention is made of the fact that
> you can't do this in a lambda, giving the impression that
> lambdas are deemed second-class citizens that are not worth
> consideration.
>
> The author was clearly aware of the issue, since a strategy
> is suggested for translation of lambdas by 2to3:
>
>     lambda (x, y): x + y --> lambda x_y: x_y[0] + x_y[1]
>
> That's a bit on the ugly side for human use, though.
> An alternative would be
>
>     lambda xy: (lambda x, y: x + y)(*xy)
>
> Whether that's any better is a matter of opinion.

There is open issue for this:

http://bugs.python.org/issue16094
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