Hi,
I wrote more pull requests in the meanwhile to see how assignment
expressions could be used in the standard library. I combined my 5 PR
into a new single PR to see all changes at once:
https://github.com/python/cpython/pull/8122/files
Again, all these PR must not be merged. I only wrote
[Victor Stinner]
> FYI I'm trying to use assignment expressions on the stdlib because
> *all* examples of the PEP 572 look artificial to me.
>
All the examples in my Appendix A were derived from real. pre-existing code
(although mostly my own). It's turned out that several others with your
2018-07-05 9:10 GMT+02:00 Tim Peters :
> I'm all in favor of what Victor is doing: looking at how this stuff will
> work in actual code. That's a great antidote to the spread of theoretical
> fears.
FYI I'm trying to use assignment expressions on the stdlib because
*all* examples of the PEP 572
On 05.07.2018 9:47, Steven D'Aprano wrote:
On Thu, Jul 05, 2018 at 12:51:37AM +0200, Victor Stinner wrote:
I propose to start the discussion about "coding style" (where are
assignment expressions appropriate or not?) with the "while True"
case.
We don't even have an official implementation
On Thu, 5 Jul 2018 13:58:42 +0300
Ivan Pozdeev via Python-Dev wrote:
> On 05.07.2018 9:23, Serhiy Storchaka wrote:
> > 05.07.18 01:51, Victor Stinner пише:
> >> == Pattern 1, straighforward ==
> >>
> >> while True:
> >> line = input.readline()
> >> if not line:
> >> break
>
On 05.07.2018 9:23, Serhiy Storchaka wrote:
05.07.18 01:51, Victor Stinner пише:
== 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.
[Victor Stinner]
>
> > I propose to start the discussion about "coding style" (where are
> > assignment expressions appropriate or not?) with the "while True"
> > case.
>
[Steven D'Aprano]
> We don't even have an official implementation yet, and you already want
> to start prescribing coding
On Thu, Jul 05, 2018 at 12:51:37AM +0200, Victor Stinner wrote:
> I propose to start the discussion about "coding style" (where are
> assignment expressions appropriate or not?) with the "while True"
> case.
We don't even have an official implementation yet, and you already want
to start
05.07.18 03:03, Victor Stinner пише:
+labels = [slabel for label
+ in self._file.readline()[1:].split(b',')
+ if (slabel := label.strip())]
labels = [slabel for label
in
05.07.18 01:51, Victor Stinner пише:
== 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()):
...
We
On 05.07.2018 1:51, Victor Stinner wrote:
Hi,
Let's say that the PEP 572 (assignment expression) is going to be
approved. Let's move on and see how it can be used in the Python
stdlib.
I propose to start the discussion about "coding style" (where are
assignment expressions appropriate or not?)
On 05/07/2018 00:15, Nathaniel Smith wrote:
On Wed, Jul 4, 2018 at 3:51 PM, Victor Stinner 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 =
On 05/07/2018 01:25, Tim Peters wrote:
== Pattern 5, two variables ==
while True:
m = match()
if not m:
break
j = m.end()
if i == j:
break
...
replaced with:
while (m := match()) and (j := m.end()) == i:
I
On 05.07.2018 3:36, Chris Angelico wrote:
On Thu, Jul 5, 2018 at 10:33 AM, Victor Stinner wrote:
2018-07-05 2:15 GMT+02:00 Chris Angelico :
On Thu, Jul 5, 2018 at 10:03 AM, Victor Stinner wrote:
On the 3360 for loops of the stdlib (*), I only found 2 loops which
would benefit of assignment
On 2018-07-05 01:11, Victor Stinner wrote:
The code comes from Lib/_pyio.py. Simplified code:
---
nodata_val = b""
...
if n is None or n == -1:
...
current_size = 0
while True:
chunk = self.raw.read()
if chunk in empty_values:
nodata_val = chunk
On Thu, Jul 5, 2018 at 10:33 AM, Victor Stinner wrote:
> 2018-07-05 2:15 GMT+02:00 Chris Angelico :
>> On Thu, Jul 5, 2018 at 10:03 AM, Victor Stinner wrote:
>>> On the 3360 for loops of the stdlib (*), I only found 2 loops which
>>> would benefit of assignment expressions.
>>>
>>> It's not easy
2018-07-05 2:15 GMT+02:00 Chris Angelico :
> On Thu, Jul 5, 2018 at 10:03 AM, Victor Stinner wrote:
>> On the 3360 for loops of the stdlib (*), I only found 2 loops which
>> would benefit of assignment expressions.
>>
>> It's not easy to find loops which:
>> - build a list,
>> - are simple enough
[Victor Stinner]Let's say that the PEP 572 (assignment expression) is going
to be
> approved. Let's move on and see how it can be used in the Python stdlib.
>
Ugh - how adult ;-)
> I propose to start the discussion about "coding style" (where are
> assignment expressions appropriate or not?)
On Thu, Jul 5, 2018 at 10:03 AM, Victor Stinner wrote:
> On the 3360 for loops of the stdlib (*), I only found 2 loops which
> would benefit of assignment expressions.
>
> It's not easy to find loops which:
> - build a list,
> - are simple enough to be expressed as list comprehension,
> - use a
The code comes from Lib/_pyio.py. Simplified code:
---
nodata_val = b""
...
if n is None or n == -1:
...
current_size = 0
while True:
chunk = self.raw.read()
if chunk in empty_values:
nodata_val = chunk
break
current_size += len(chunk)
On the 3360 for loops of the stdlib (*), I only found 2 loops which
would benefit of assignment expressions.
It's not easy to find loops which:
- build a list,
- are simple enough to be expressed as list comprehension,
- use a condition (if),
- use an expression different than just a variable
On 2018-07-04 23:51, Victor Stinner wrote:
[snip]
(C)
while True:
chunk = self.raw.read()
if chunk in empty_values:
nodata_val = chunk
break
...
"nodata_val = chunk" cannot be put into the "chunk := self.raw.read()"
assignment expression combined with a test.
On Wed, Jul 4, 2018 at 3:51 PM, Victor Stinner 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:
>
Hi,
Let's say that the PEP 572 (assignment expression) is going to be
approved. Let's move on and see how it can be used in the Python
stdlib.
I propose to start the discussion about "coding style" (where are
assignment expressions appropriate or not?) with the "while True"
case.
I wrote a WIP
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