Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

On Wed, Jun 27, 2018 at 12:01 PM, Eric V. Smith wrote: > >>> def test(): > >>>spam = 1 > >>>ham = 2 > >>>vars = [key1+key2 for key1 in locals() for key2 in locals()] > >>>return vars > >>> > >>> Wanna guess what that's gonna return? > Guessing aside, messing around with locals()

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

[Guido] > .. > Given that definition of `__parentlocal`, in first approximation the > scoping rule proposed by PEP 572 would then be: In comprehensions > (which in my use in the PEP 572 discussion includes generator > expressions) the targets of inline assignments are automatically > endowed with

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

On Thu, Jun 28, 2018 at 11:29 AM, Ivan Pozdeev via Python-Dev wrote: > On 28.06.2018 2:44, Greg Ewing wrote: >> >> Ivan Pozdeev via Python-Dev wrote: >>> >>> for me, the primary use case for an assignment expression is to be able >>> to "catch" a value into a variable in places where I can't put

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

On 28.06.2018 2:44, Greg Ewing wrote: Ivan Pozdeev via Python-Dev wrote: for me, the primary use case for an assignment expression is to be able to "catch" a value into a variable in places where I can't put an assignment statement in, like the infamous `if re.match() is not None'. This

[Python-Dev] Python 3.7.0 is now available! (and so is 3.6.6)

On behalf of the Python development community and the Python 3.7 release team, we are pleased to announce the availability of Python 3.7.0. Python 3.7.0 is the newest feature release of the Python language, and it contains many new features and optimizations. You can find Python 3.7.0 here:

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

[Tim] > If the parent has a matching parentlocal declaration for the same > name then the original > > really refers to the grandparent - and so on. > [Greg] > Ah, I missed that part, sorry -- I withdraw that particular > objecttion. > Good! I have another reply that crossed in the mail.

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

Ivan Pozdeev via Python-Dev wrote: for me, the primary use case for an assignment expression is to be able to "catch" a value into a variable in places where I can't put an assignment statement in, like the infamous `if re.match() is not None'. This seems to be one of only about two uses for

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

> [Nick Coghlan] > I'm OK with a target scope declaration construct having > > lexical-scope-dependent behaviour - exactly what "nonlocal NAME" will > > do depends on both the nature of the current scope, > [Greg Ewing] > Yes, but my point is that having an explicit "parentlocal" scope >

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

Tim Peters wrote: If the parent has a matching parentlocal declaration for the same name then the original really refers to the grandparent - and so on. Ah, I missed that part, sorry -- I withdraw that particular objecttion. Still, this seems like a major addition (seeing as it comes with a

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

On 28.06.2018 2:31, Greg Ewing wrote: Steven D'Aprano wrote: The *very first* motivating example for this proposal came from a comprehension. I think it is both unfortunate and inevitable that the discussion bogged down in comprehension-hell. I think the unfortunateness started when we

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

Ivan Pozdeev via Python-Dev wrote: This isn't as messy as you make it sound if you remember that the outermost iterable is evaluated only once at the start and all the others -- each iteration. Anyone using comprehensions has to know this fact. That fact alone doesn't imply anthing about the

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

On 28.06.2018 2:45, Ivan Pozdeev via Python-Dev wrote: On 28.06.2018 2:31, Ivan Pozdeev via Python-Dev wrote: On 28.06.2018 1:42, Steven D'Aprano wrote: On Wed, Jun 27, 2018 at 05:52:16PM +0300, Ivan Pozdeev via Python-Dev wrote: What this means in practice is that assignments will go to

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

Nick Coghlan wrote: I'm OK with a target scope declaration construct having lexical-scope-dependent behaviour - exactly what "nonlocal NAME" will do depends on both the nature of the current scope, Yes, but my point is that having an explicit "parentlocal" scope declaration doesn't help to

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

On 28.06.2018 2:31, Ivan Pozdeev via Python-Dev wrote: On 28.06.2018 1:42, Steven D'Aprano wrote: On Wed, Jun 27, 2018 at 05:52:16PM +0300, Ivan Pozdeev via Python-Dev wrote: What this means in practice is that assignments will go to different scopes depending on *where* they are in the

Re: [Python-Dev] Intent to accept PEP 561 -- Distributing and Packaging Type Information

On 06/27/2018 04:11 PM, Guido van Rossum wrote: Well, with that, I am hereby accepting PEP 561. Congratulations, Ethan! :) -- ~Ethan~ ___ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

On 28.06.2018 1:42, Steven D'Aprano wrote: On Wed, Jun 27, 2018 at 05:52:16PM +0300, Ivan Pozdeev via Python-Dev wrote: What this means in practice is that assignments will go to different scopes depending on *where* they are in the comprehension: [ expr for x in iter1 for y in iter2

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

Steven D'Aprano wrote: The *very first* motivating example for this proposal came from a comprehension. I think it is both unfortunate and inevitable that the discussion bogged down in comprehension-hell. I think the unfortunateness started when we crossed over from talking about binding a

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

On Wed, Jun 27, 2018 at 9:27 AM Paul Moore wrote: > From my reading, PEP 572 takes the position that "parent local > scoping" is what people expect from assignment expressions *in > comprehensions* and it's useful enough that there is no reason not to > make that the behaviour. The behaviour

Re: [Python-Dev] Intent to accept PEP 561 -- Distributing and Packaging Type Information

Congrats Ethan, Well done! I think PEP 561 will significantly simplify typing third party modules. -- Ivan On 28 June 2018 at 00:11, Guido van Rossum wrote: > Well, with that, I am hereby accepting PEP 561. > > Ethan has done a tremendous job writing this PEP and implementing it, and > I am

Re: [Python-Dev] Intent to accept PEP 561 -- Distributing and Packaging Type Information

Well, with that, I am hereby accepting PEP 561. Ethan has done a tremendous job writing this PEP and implementing it, and I am sure that package and stub authors will be very glad to hear that there are now officially supported ways other than typeshed to distribute type annotations. Congrats

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

On Wed, Jun 27, 2018 at 05:52:16PM +0300, Ivan Pozdeev via Python-Dev wrote: > >What this means in practice is that assignments will go to different > >scopes depending on *where* they are in the comprehension: > > > > [ expr for x in iter1 for y in iter2 if cond ...] > > [ BB

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

So IIUC you are okay with the behavior described by the PEP but you want an explicit language feature to specify it? I don't particularly like adding a `parentlocal` statement to the language, because I don't think it'll be generally useful. (We don't have `goto` in the language even though it

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

> On Jun 27, 2018, at 9:49 AM, Steven D'Aprano wrote: > >> On Wed, Jun 27, 2018 at 08:00:20AM -0400, Eric V. Smith wrote: >>> On 6/27/2018 7:08 AM, Chris Angelico wrote: >>> It gets funnier with nested loops. Or scarier. I've lost the ability >>> to distinguish those two. >>> >>> def test():

Re: [Python-Dev] Policy on refactoring/clean up

In itself, the code clean up you have done is a good thing in the sense that you re-organized things and in my understanding, they look good now. In some of the teams I've been granted to work, there was a rule stating that whenever a dev would work on an enhancement/bugfix, he would create a

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

[Nick Coghlan] > However, PEP 572 in its current form takes the position "parent local > scoping is sufficiently useful to make it a required pre-requisite for > adding assignment expressions, but not useful enough to expose as a > new scope declaration primitive", > Of course the PEP doesn't

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

[Nick Coghlan]> > actually made those semantics available as an explicit > "parentlocal NAME" declaration ...: > > > > def _list_comp(_outermost_iter): > > parentlocal item > > _result = [] > > for x in _outermost_iter: > > item = x > >

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

On 27 June 2018 at 15:39, Nick Coghlan wrote: > However, PEP 572 in its current form takes the position "parent local > scoping is sufficiently useful to make it a required pre-requisite for > adding assignment expressions, but not useful enough to expose as a > new scope declaration primitive",

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

On 27.06.2018 16:49, Steven D'Aprano wrote: On Wed, Jun 27, 2018 at 08:00:20AM -0400, Eric V. Smith wrote: On 6/27/2018 7:08 AM, Chris Angelico wrote: It gets funnier with nested loops. Or scarier. I've lost the ability to distinguish those two. def test(): spam = 1 ham = 2

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

On 27 June 2018 at 23:38, Greg Ewing wrote: > Nick Coghlan wrote: >> >> actually made those semantics available as an explicit >> "parentlocal NAME" declaration ...: >> >> def _list_comp(_outermost_iter): >> parentlocal item >> _result = [] >> for x in _outermost_iter:

Re: [Python-Dev] Python and Linux Standard Base

On 27 June 2018 at 23:57, Charalampos Stratakis wrote: > From: "Antoine Pitrou" >> One question: who maintains the LSB? >> >> The fact that the Python portion was never updated may hint that nobody >> uses it... > > That could definitely be the case here. I stumbled upon that when checking >

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

On 27.06.2018 16:25, Greg Ewing wrote: Ivan Pozdeev via Python-Dev wrote: Using this assigned result elsewhere in the same expression (akin to regex backreferences) is not a part of the basic idea actually. If that's true, then the proposal has mutated into something that has *no* overlap

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

On Wed, Jun 27, 2018 at 03:41:23PM +0200, Antoine Pitrou wrote: > > Why is this discussion talking about comprehensions at all? > Is there a decent use case for using assignments in comprehensions (as > opposed to language lawyering or deliberate obfuscation)? Yes. The *very first* motivating

Re: [Python-Dev] Python and Linux Standard Base

- Original Message - > From: "Antoine Pitrou" > To: python-dev@python.org > Sent: Wednesday, June 27, 2018 3:42:53 PM > Subject: Re: [Python-Dev] Python and Linux Standard Base > > On Wed, 27 Jun 2018 09:18:24 -0400 (EDT) > Charalampos Stratakis wrote: > > > > My question is, if

Re: [Python-Dev] Python and Linux Standard Base

The main wiki page was last touched at all in 2016. The mailing list in Jan 2018 had about 8 comments, none of them actually related to LSB. They stopped archiving the ML altogether in Feb 2018. I think it's safe to say the parrot is dead. On Wed, Jun 27, 2018, 9:50 AM Antoine Pitrou wrote: >

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

On Wed, Jun 27, 2018 at 08:00:20AM -0400, Eric V. Smith wrote: > On 6/27/2018 7:08 AM, Chris Angelico wrote: > >It gets funnier with nested loops. Or scarier. I've lost the ability > >to distinguish those two. > > > >def test(): > > spam = 1 > > ham = 2 > > vars = [key1+key2 for key1

Re: [Python-Dev] Python and Linux Standard Base

On Wed, 27 Jun 2018 09:18:24 -0400 (EDT) Charalampos Stratakis wrote: > > My question is, if there is any incentive to try and ask for > modernization/amendment of the standards? > I really doubt that any linux distro at that point can be considered lsb > compliant at least from the > python

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

Why is this discussion talking about comprehensions at all? Is there a decent use case for using assignments in comprehensions (as opposed to language lawyering or deliberate obfuscation)? Regards Antoine. On Thu, 28 Jun 2018 01:25:14 +1200 Greg Ewing wrote: > Ivan Pozdeev via Python-Dev

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

Nick Coghlan wrote: actually made those semantics available as an explicit "parentlocal NAME" declaration ...: def _list_comp(_outermost_iter): parentlocal item _result = [] for x in _outermost_iter: item = x _result.append(x) return

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

Ivan Pozdeev via Python-Dev wrote: Using this assigned result elsewhere in the same expression (akin to regex backreferences) is not a part of the basic idea actually. If that's true, then the proposal has mutated into something that has *no* overlap whatsoever with the use case that started

[Python-Dev] Python and Linux Standard Base

LSB (Linux Standard Base) is a set of standards defined from the Linux Foundation for linux distributions [0][1] with the latest version (LSB 5.0) released on 3rd of June, 2015. Python is also mentioned there but the information is horribly outdated [2]. For example here are the necessary

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

On 27.06.2018 5:36, Guido van Rossum wrote: [This is my one response today] On Mon, Jun 25, 2018 at 12:40 PM Terry Reedy > wrote: On 6/24/2018 7:25 PM, Guido van Rossum wrote: > I'd wager that the people who might be most horrified about it the (b)

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

On 26 June 2018 at 02:27, Guido van Rossum wrote: > [This is my one reply in this thread today. I am trying to limit the amount > of time I spend to avoid another overheated escalation.] Aye, I'm trying to do the same, and deliberately spending some evenings entirely offline is helping with that

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

On 6/27/2018 7:08 AM, Chris Angelico wrote: It gets funnier with nested loops. Or scarier. I've lost the ability to distinguish those two. def test(): spam = 1 ham = 2 vars = [key1+key2 for key1 in locals() for key2 in locals()] return vars Wanna guess what that's gonna

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

On Wed, Jun 27, 2018 at 7:19 PM, Steven D'Aprano wrote: > On Wed, Jun 27, 2018 at 05:52:16PM +1000, Chris Angelico wrote: > >> def test(): >> a = 1 >> b = 2 >> vars = {key: locals()[key] for key in locals()} >> return vars >> >> What would your intuition say? Should this be

Re: [Python-Dev] PEP 576

On 2018-06-26 21:43, Mark Shannon wrote: https://github.com/markshannon/pep-576 This actually looks close to Victor Stinner's bpo-29259. But instead of storing the function pointer in the class, you're storing it in the instance. One concern that I have is that this might lead to code

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

On 26.06.2018 1:34, Greg Ewing wrote: Ivan Pozdeev via Python-Dev wrote: "as" was suggested even before is became a keyword in `with'. ( if (re.match(regex,line) as m) is not None: ) That's not equivalent where/given, though, since it still has the asymmetry problem. What do you mean by

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

On Wed, Jun 27, 2018 at 05:52:16PM +1000, Chris Angelico wrote: > def test(): > a = 1 > b = 2 > vars = {key: locals()[key] for key in locals()} > return vars > > What would your intuition say? Should this be equivalent to dict(locals()) ? That example is so elegant it makes me

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

On Wed, Jun 27, 2018 at 08:30:00AM +0100, Paul Moore wrote: > On 27 June 2018 at 07:54, Steven D'Aprano wrote: > > Comprehensions already run partly in the surrounding scope. [...] > > Given the code shown: > > > > def test(): > > a = 1 > > b = 2 > > result = [value for key, value in

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

On 27 June 2018 at 08:52, Chris Angelico wrote: > On Wed, Jun 27, 2018 at 5:30 PM, Paul Moore wrote: >> But test() returns [1, 2]. So does that say (as you claim above) that >> "the comprehension ran in the enclosing scope"? Doesn't it just say >> that the outermost iterable runs in the

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

On Wed, Jun 27, 2018 at 5:30 PM, Paul Moore wrote: > But test() returns [1, 2]. So does that say (as you claim above) that > "the comprehension ran in the enclosing scope"? Doesn't it just say > that the outermost iterable runs in the enclosing scope? Yes - because the *outermost iterable* runs

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

On Tue, Jun 26, 2018 at 10:54:12AM +1200, Greg Ewing wrote: > A decision still needs to be made about whether we *want* > semantics that leak some things but not others. My sense (or bias, if you prefer) is that the answer to that depends on how you word the question. If you talk about

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

On 27 June 2018 at 07:54, Steven D'Aprano wrote: > Comprehensions already run partly in the surrounding scope. > > I tried to take a survey of people on the Python-List mailing list, so > see what their expectations of comprehension scope was. Disappointingly, > not many people responded, but

Re: [Python-Dev] Informal educator feedback on PEP 572 (was Re: 2018 Python Language Summit coverage, last part)

On Tue, Jun 26, 2018 at 05:42:43AM +1000, Chris Angelico wrote: > So. sublocal scopes, like in the earliest versions of PEP 572? > > The wheel turns round and round, and the same spokes come up. It isn't as if comprehensions (and generator expressions) run in a proper separate scope. It is