Re: [Python-Dev] (name := expression) doesn't fit the narrative of PEP 20

2018年4月26日 11:57:06 -0700 

On 4/26/2018 6:20 AM, Steve Holden wrote:
On Thu, Apr 26, 2018 at 8:56 AM, Steven D'Aprano <[email protected] <mailto:[email protected]>> wrote: 
 On Thu, Apr 26, 2018 at 03:31:13AM -0400, Terry Reedy wrote:
 > On 4/25/2018 8:20 PM, Chris Angelico wrote:
 > >On Thu, Apr 26, 2018 at 10:11 AM, Yury Selivanov
 > ><[email protected] <mailto:[email protected]>> wrote:
 > >>Just yesterday this snippet was used on python-dev to show how great the
 > >>new syntax is:
 > >>
 > >>      my_func(arg, buffer=(buf := [None]*get_size()), 
size=len(buf))
> > What strikes me as awful about this example is that len(buf) is > get_size(), so the wrong value is being named and saved. > 'size=len(buf)' is, in a sense, backwards. 
 Terry is absolutely right, and I'm to blame for that atrocity. Mea
 culpa.
​Perhaps a better spelling would be
   my_func(arg, buffer=[None]*(buflen := get_size()), size=buflen)

That is exactly what I wrote in the continuation that Steven snipped.
--
Terry Jan Reedy
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