2018-04-26 13:20 GMT+03:00 Steve Holden <steve@holdenweb.com>:
On Thu, Apr 26, 2018 at 8:56 AM, Steven D'Aprano <steve@pearwood.info> wrote:
On 4/25/2018 8:20 PM, Chris Angelico wrote:
On Thu, Apr 26, 2018 at 10:11 AM, Yury Selivanov <yselivanov.ml@gmail.com> wrote:
Just yesterday this snippet was used on python-dev to show how great
On Thu, Apr 26, 2018 at 03:31:13AM -0400, Terry Reedy wrote: 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)
I know it is non productive and spamy (I promise, this is the last) since `as` syntax is dead. In many cases, there is not much difference in perception between `:=` and `as`. But in several situations, like this one and as Ethan pointed up-thread - the expression first syntax makes obvious the intent and linearly readable: my_func(arg, buffer=[None]*get_size() as buf, size=buf) In any case, it is rather an anti-pattern than a good example to follow. p.s.: as Victor Stinner wrote on twitter that previously, there was a similar PEP in spirit - "PEP 379 -- Adding an Assignment Expression", which was withdrawn. May be it is worth to make a link to it in the current PEP. With kind regards, -gdg