On 05/07/2018 00:15, Nathaniel Smith wrote:
On Wed, Jul 4, 2018 at 3:51 PM, Victor Stinner <vstin...@redhat.com> wrote:
My question is now: for which "while True" patterns are the assignment
expression appropriate? There identified different patterns.
== Pattern 1, straighforward ==
while True:
line = input.readline()
if not line:
break
...
IMHO here assingment expression is appropriate here. The code remains
straighfoward to read.
while (line := input.readline()):
...
There are some obvious caveats here – no-one has real experience with
:= yet, so any opinions right now are informed guesswork that will
probably change some if/when we get more experience with it.
Of course, this is absolutely true. But ...
Also, the
stdlib is a big place, and it seems inevitable that maintainers of
different modules will have different preferences. So I don't think it
makes sense to try to define some Official Universal Rule about when
:= is appropriate and when it isn't.
That said, FWIW, my current feeling is that this simplest case is the
only one where I would use :=; for your other examples I'd stick with
the loop-and-a-half style.
... even you, Nathaniel (correct me if I'm wrong, but you seem to be
generally against PEP 572) would use := in (at least) one case.
I predict: We'll all end up loving Assignment Expressions (like
f-strings) once we've got used to them. Or just taking them for
granted. No doubt some of us will use them more than others, some
perhaps not at all.
Regards
Rob Cliffe
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