[issue35224] PEP 572: Assignment Expressions

Guido van Rossum added the comment: Congrats! Let's party. -- ___ Python tracker ___ ___ Python-bugs-list mailing list

[issue35224] PEP 572: Assignment Expressions

Emily Morehouse added the comment: All areas that were identified for additional work have been addressed. If there is anything else that needs to be improved or updated, please create a new issue. Thanks! -- resolution: -> fixed stage: patch review -> resolved status: open ->

[issue35224] PEP 572: Assignment Expressions

Stéphane Wirtel added the comment: New changeset be2aa58fdc29cf13aabff6d6712e7853e94e88f8 by Stéphane Wirtel (Miss Islington (bot)) in branch '3.8': bpo-35224: Additional documentation for Assignment Expressions (GH-15935) (GH-15967)

[issue35224] PEP 572: Assignment Expressions

miss-islington added the comment: New changeset 6357c95716d89ac1f80587fbc4133df8d2e8396c by Miss Islington (bot) (Emily Morehouse) in branch 'master': bpo-35224: Additional documentation for Assignment Expressions (GH-15935)

[issue35224] PEP 572: Assignment Expressions

Change by miss-islington : -- pull_requests: +15600 pull_request: https://github.com/python/cpython/pull/15967 ___ Python tracker ___

[issue35224] PEP 572: Assignment Expressions

Change by Emily Morehouse : -- pull_requests: +15572 pull_request: https://github.com/python/cpython/pull/15935 ___ Python tracker ___

[issue35224] PEP 572: Assignment Expressions

Nick Coghlan added the comment: Proposed PEP update is here: https://github.com/python/peps/pull/1140 The update also aims to clarify *why* we're doing the extra work in CPython's compiler to make these cases fail (i.e. we don't want to implicitly impose the current CPython runtime

[issue35224] PEP 572: Assignment Expressions

Guido van Rossum added the comment: Can you suggest a PEP update too, for the case that goes beyond the PEP? And please provide examples (not everybody knows immediately what "outermost iterable expression" refers to. :-) -- ___ Python tracker

[issue35224] PEP 572: Assignment Expressions

Nick Coghlan added the comment: Thanks Guido. The former test cases that the new PR removes are the following: res = [i := i for i in range(5)] res = [i := 0 for i, j in [(1, 2), (3, 4)]] res = [(i := 0, j := 1) for i, j in [(1, 2), (3, 4)]] res = [(i := i, j := j) for i, j in [(1, 2), (3,

[issue35224] PEP 572: Assignment Expressions

Nick Coghlan added the comment: #37757 now has an associated PR adding the missing TargetScopeError cases: https://github.com/python/cpython/pull/15131 There's one case where it goes beyond what the PEP specifies: because the outermost iterable expression gets evaluated in a different scope

[issue35224] PEP 572: Assignment Expressions

Guido van Rossum added the comment: Thanks for catching that this was still incomplete. > Also, a major procedural note: it is NOT OK to merge a PEP implementation > that completely ignores parts of the PEP. The merged tests are actively > forcing NON-compliance with the accepted PEP, since

[issue35224] PEP 572: Assignment Expressions

Raymond Hettinger added the comment: FWIW, I'm working on an improved whatsnew entry in https://github.com/python/cpython/pull/15127 -- ___ Python tracker ___

[issue35224] PEP 572: Assignment Expressions

Nick Coghlan added the comment: Also, a major procedural note: it is NOT OK to merge a PEP implementation that completely ignores parts of the PEP. The merged tests are actively forcing NON-compliance with the accepted PEP, since they're requiring implementations to accept code that the PEP

[issue35224] PEP 572: Assignment Expressions

Nick Coghlan added the comment: https://bugs.python.org/issue37757 separates out the TargetScopeError handling for conflicts between assignment expressions and comprehension iteration variables. -- ___ Python tracker

[issue35224] PEP 572: Assignment Expressions

Nick Coghlan added the comment: Did the documentation PR get pushed/merged? Emily mentioned having one in progress above, but it doesn't appear in the linked PRs. -- nosy: +ncoghlan ___ Python tracker

[issue35224] PEP 572: Assignment Expressions

Barry A. Warsaw added the comment: I might be missing it, but I think the Language Reference still doesn't document assignment expressions. https://docs.python.org/3/reference/lexical_analysis.html#operators There are likely other places in the LR that need to be filled out with PEP 572

[issue35224] PEP 572: Assignment Expressions

miss-islington added the comment: New changeset ced9e11931a7a1c5cf4eef08d0dd4a4886723b43 by Miss Islington (bot) in branch '3.8': bpo-35224: Add What's new entry for evaluation order in dict comprehensions (GH-14319)

[issue35224] PEP 572: Assignment Expressions

Change by miss-islington : -- pull_requests: +14178 pull_request: https://github.com/python/cpython/pull/14361 ___ Python tracker ___

[issue35224] PEP 572: Assignment Expressions

Pablo Galindo Salgado added the comment: New changeset b51b7137faa22e12c570c70fe0462c662ccd935e by Pablo Galindo in branch 'master': bpo-35224: Add What's new entry for evaluation order in dict comprehensions (GH-14319)

[issue35224] PEP 572: Assignment Expressions

miss-islington added the comment: New changeset 175b2e974586152c1d4cdea589b971d7ecad4d30 by Miss Islington (bot) in branch '3.8': bpo-35224: Bump the pyc magic number by 1 instead of by 10 in last modification (GH-14320)

[issue35224] PEP 572: Assignment Expressions

Pablo Galindo Salgado added the comment: New changeset b3ca7972c8d8c6479b6542ce28e0f7a6ebd5b8fe by Pablo Galindo in branch 'master': bpo-35224: Bump the pyc magic number by 1 instead of by 10 in last modification (GH-14320)

[issue35224] PEP 572: Assignment Expressions

Change by miss-islington : -- pull_requests: +14145 pull_request: https://github.com/python/cpython/pull/14321 ___ Python tracker ___

[issue35224] PEP 572: Assignment Expressions

Change by Pablo Galindo Salgado : -- pull_requests: +14144 pull_request: https://github.com/python/cpython/pull/14320 ___ Python tracker ___

[issue35224] PEP 572: Assignment Expressions

Change by Pablo Galindo Salgado : -- pull_requests: +14143 pull_request: https://github.com/python/cpython/pull/14319 ___ Python tracker ___

[issue35224] PEP 572: Assignment Expressions

Serhiy Storchaka added the comment: So issue29652 can be closed now? Was all concerns of previous discussions addressed? I suggest to increment the magic number by 1, not by 10. The space of magic numbers is finite. Add please a What's New entry for this change. -- nosy:

[issue35224] PEP 572: Assignment Expressions

Pablo Galindo Salgado added the comment: All buildbots for 3.8 and master are green again :) -- ___ Python tracker ___ ___

[issue35224] PEP 572: Assignment Expressions

Guido van Rossum added the comment: How are the buildbots doing now? -- ___ Python tracker ___ ___ Python-bugs-list mailing list

[issue35224] PEP 572: Assignment Expressions

miss-islington added the comment: New changeset 5c8b4e2b5de647a67dd1b6414fa520d2b8e973aa by Miss Islington (bot) in branch '3.8': bpo-35224: Bump the pyc magic number after the change in MAP_ADD (GH-14313) https://github.com/python/cpython/commit/5c8b4e2b5de647a67dd1b6414fa520d2b8e973aa

[issue35224] PEP 572: Assignment Expressions

Change by miss-islington : -- pull_requests: +14138 pull_request: https://github.com/python/cpython/pull/14315 ___ Python tracker ___

[issue35224] PEP 572: Assignment Expressions

Pablo Galindo Salgado added the comment: New changeset 663131a6e2c6c8b83e9f982d8c6ca38fc7c238b4 by Pablo Galindo in branch 'master': bpo-35224: Bump the pyc magic number after the change in MAP_ADD (GH-14313) https://github.com/python/cpython/commit/663131a6e2c6c8b83e9f982d8c6ca38fc7c238b4

[issue35224] PEP 572: Assignment Expressions

miss-islington added the comment: New changeset 874ff65e0a70ff4fd1a67e85cd61d76adfcc219d by Miss Islington (bot) in branch '3.8': bpo-35224: Reverse evaluation order of key: value in dict comprehensions (GH-14139)

[issue35224] PEP 572: Assignment Expressions

Guido van Rossum added the comment: I don't know why the failure is Windows-only, but I suspect that some of the cleanup doesn't work there... This definitely needs a bump of the pyc format version number. -- ___ Python tracker

[issue35224] PEP 572: Assignment Expressions

Change by miss-islington : -- pull_requests: +14137 pull_request: https://github.com/python/cpython/pull/14314 ___ Python tracker ___

[issue35224] PEP 572: Assignment Expressions

Pablo Galindo Salgado added the comment: Although it can be related, note that the buildbots do indeed delete pyc files. Check for example https://buildbot.python.org/all/#/builders/40/builds/2621/steps/2/logs/stdio : ... Deleting .pyc/.pyo files ... Deleting test leftovers ... Using

[issue35224] PEP 572: Assignment Expressions

Pablo Galindo Salgado added the comment: I have created PR14313 and triggered a custom build from that PR in the buildbots to confirm our hypothesis. -- ___ Python tracker

[issue35224] PEP 572: Assignment Expressions

Change by Pablo Galindo Salgado : -- pull_requests: +14136 pull_request: https://github.com/python/cpython/pull/14313 ___ Python tracker ___

[issue35224] PEP 572: Assignment Expressions

Guido van Rossum added the comment: Ouch. That means we need to buy.p the puck format version number. -- --Guido (mobile) -- ___ Python tracker ___

[issue35224] PEP 572: Assignment Expressions

Jörn Heissler added the comment: My working theory: The change modifies the MAP_ADD instruction and also what the instruction expects to find on the stack. When *.pyc files are kept, the code generates the old stack layout (TOS=key, TOS1=value), but cpython will assume it's the other way

[issue35224] PEP 572: Assignment Expressions

Jörn Heissler added the comment: Sorry, I guess that's something completely different. So maybe the issue is related to my pull request. -- ___ Python tracker ___

[issue35224] PEP 572: Assignment Expressions

Jörn Heissler added the comment: Pablo, https://bugs.python.org/issue37359 was created yesterday, i.e. before the merge. -- ___ Python tracker ___

[issue35224] PEP 572: Assignment Expressions

Pablo Galindo Salgado added the comment: All the stable 3.x Windows buildbots are failing since (https://github.com/python/cpython/pull/14139) was merged: https://buildbot.python.org/all/#/builders/3/builds/3026 https://buildbot.python.org/all/#/builders/40/builds/2621

[issue35224] PEP 572: Assignment Expressions

miss-islington added the comment: New changeset c8a35417db8853a253517a3e5190e174075c6384 by Miss Islington (bot) (Jörn Heissler) in branch 'master': bpo-35224: Reverse evaluation order of key: value in dict comprehensions (GH-14139)

[issue35224] PEP 572: Assignment Expressions

Jörn Heissler added the comment: I tried and it appears to work: https://github.com/python/cpython/pull/14139 As I'm not familiar with cpython code, chances are that I missed something important. -- ___ Python tracker

[issue35224] PEP 572: Assignment Expressions

Change by Jörn Heissler : -- pull_requests: +13980 pull_request: https://github.com/python/cpython/pull/14139 ___ Python tracker ___

[issue35224] PEP 572: Assignment Expressions

Guido van Rossum added the comment: Do you want to give it a try yourself? On Sun, Jun 16, 2019 at 14:42 Jörn Heissler wrote: > > Jörn Heissler added the comment: > > Hello, > > https://www.python.org/dev/peps/pep-0572/#change-to-evaluation-order > mentions a change of evaluation order for

[issue35224] PEP 572: Assignment Expressions

Jörn Heissler added the comment: Hello, https://www.python.org/dev/peps/pep-0572/#change-to-evaluation-order mentions a change of evaluation order for dict comprehensions. It looks like this is not implemented yet (as of commit 66d47da8). Will this be implemented in this issue, or should I

[issue35224] PEP 572: Assignment Expressions

Change by Chris Angelico : -- pull_requests: +13077 ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe:

[issue35224] PEP 572: Assignment Expressions

Guido van Rossum added the comment: > Maybe we could update the What's New quickly now, and then get the longer > more complex docs done later? People have been asking if this feature is in > 3.8 because they don't see it mentioned. Here it is (PR 12941) --

[issue35224] PEP 572: Assignment Expressions

Change by Guido van Rossum : -- pull_requests: +12865 ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe:

[issue35224] PEP 572: Assignment Expressions

Guido van Rossum added the comment: I will add stub sections to the 3.8 whatsnew. -- ___ Python tracker ___ ___ Python-bugs-list

[issue35224] PEP 572: Assignment Expressions

Vedran Čačić added the comment: ... and probably also because they start Python, type x := 2 and get SyntaxError (as explained above). ;-) -- ___ Python tracker ___

[issue35224] PEP 572: Assignment Expressions

Ned Batchelder added the comment: Maybe we could update the What's New quickly now, and then get the longer more complex docs done later? People have been asking if this feature is in 3.8 because they don't see it mentioned. -- ___ Python

[issue35224] PEP 572: Assignment Expressions

Emily Morehouse added the comment: Ned is correct! I will be sprinting on docs for this at PyCon. -- ___ Python tracker ___ ___

[issue35224] PEP 572: Assignment Expressions

Ned Batchelder added the comment: 3.8.0a3 is out, and the What's New still doesn't mention this work yet. -- nosy: +nedbat ___ Python tracker ___

[issue35224] PEP 572: Assignment Expressions

Vedran Čačić added the comment: Carol, if you're willing to go into the lion's den that is Python-ideas with this, you have my eternal gratitude. :-) Steven, sorry, there really is no rush. I really don't think I ever said there is. However, I think it would be much easier to change the

[issue35224] PEP 572: Assignment Expressions

Change by STINNER Victor : -- nosy: -vstinner ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe:

[issue35224] PEP 572: Assignment Expressions

STINNER Victor added the comment: The bug tracker is not the appropriate place to discuss a PEP. This issue is about the implementation of the PEP. -- ___ Python tracker ___

[issue35224] PEP 572: Assignment Expressions

Steven D'Aprano added the comment: You are one person, who has used this feature for what, a month elapsed time? 300 person-hours actual experience with it? Allowing top-level unparenthisized walrus expressions will affect hundreds of thousands of people, for collectively millions of hours

[issue35224] PEP 572: Assignment Expressions

Carol Willing added the comment: @veky As a Jupyter notebook maintainer, I can see your point and I suspect some would like it. I'm not sure how big a benefit it would be for folks based on current notebook usage and practices. I just don't know. It's worth a discussion, but it should take

[issue35224] PEP 572: Assignment Expressions

Change by Miro Hrončok : -- nosy: -hroncok ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe:

[issue35224] PEP 572: Assignment Expressions

Vedran Čačić added the comment: Sorry, I don't have the energy for endless discussions without any result that almost always happen there. If you - of all people - don't see an obvious benefit of this (not even a feature - just a removal of a quite pointless limitation), then I'm probably

[issue35224] PEP 572: Assignment Expressions

Guido van Rossum added the comment: @veky -- please take this up on python-ideas. -- ___ Python tracker ___ ___ Python-bugs-list

[issue35224] PEP 572: Assignment Expressions

Vedran Čačić added the comment: Now I had the opportunity to play with the walrus (as it is affectionately called in some parts of the community), I have to ask you for a reconsideration of one part of PEP 572. Unparenthesized assignment expressions are prohibited at the top level of an

[issue35224] PEP 572: Assignment Expressions

Change by Kubilay Kocak : -- nosy: +koobs ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe:

[issue35224] PEP 572: Assignment Expressions

STINNER Victor added the comment: > If anyone has another area they think the documentation should be updated, > please let me know! If we forget something, it's not an issue: it can be added later! -- ___ Python tracker

[issue35224] PEP 572: Assignment Expressions

Emily Morehouse added the comment: I have a work-in-progress (WIP) documentation branch I've been working on that I'll push up this week to address the following: - Add summary to What's New in Doc/whatsnew/3.8.rst - Add to list of delimiters in Doc/reference/lexical_analysis.rst - Add usage

[issue35224] PEP 572: Assignment Expressions

Miro Hrončok added the comment: (I've somehow missed the previous comments about the same, sorry about that.) -- ___ Python tracker ___

[issue35224] PEP 572: Assignment Expressions

Miro Hrončok added the comment: PEP 572 is nowhere to be found in https://docs.python.org/3.8/whatsnew/3.8.html Should I open a separate issue for that? -- nosy: +hroncok ___ Python tracker

[issue35224] PEP 572: Assignment Expressions

Emily Morehouse added the comment: @rhettinger absolutely, I'm going to include that in my documentation PR which is currently in progress. :) -- ___ Python tracker ___

[issue35224] PEP 572: Assignment Expressions

Raymond Hettinger added the comment: FYI, we need a prominent Whatsnew entry for this. -- nosy: +rhettinger ___ Python tracker ___

[issue35224] PEP 572: Assignment Expressions

STINNER Victor added the comment: Note: I checked and 3.x buildbots are back to green (ignoring the ones which already failed previously). Good. -- ___ Python tracker ___

[issue35224] PEP 572: Assignment Expressions

Karthikeyan Singaravelan added the comment: I don't know if this is the correct issue for questions/clarifications but it seems parens are mandatory while using named expressions in while statement which makes some of the examples invalid like

[issue35224] PEP 572: Assignment Expressions

STINNER Victor added the comment: New changeset 1396d8fab4d0ae830d45f4937322bbb43ce0c30e by Victor Stinner in branch 'master': bpo-35224: Add support for NamedExpr to unparse.py (GH-11670) https://github.com/python/cpython/commit/1396d8fab4d0ae830d45f4937322bbb43ce0c30e --

[issue35224] PEP 572: Assignment Expressions

STINNER Victor added the comment: > @vstinner Is there something I could/should have checked other than the CI > displayed in GitHub before merging? Let me know if I can help. It wasn't your fault. Our pre-commit checks on pull requests is incomplete on purpose: it has to be fast. It's fine

[issue35224] PEP 572: Assignment Expressions

Emily Morehouse added the comment: @vstinner Is there something I could/should have checked other than the CI displayed in GitHub before merging? Let me know if I can help. Here's a brief summary of the differences between the PEP spec and implementation: >From the "Scope of the target"

[issue35224] PEP 572: Assignment Expressions

STINNER Victor added the comment: The change broke most buildbots: congrats Emily, each core dev has to do their as part of their training ;-) Don't worry, it's fine. I wrote PR #11670 which should fix test_tools. -- nosy: +vstinner ___ Python

[issue35224] PEP 572: Assignment Expressions

Change by STINNER Victor : -- pull_requests: +11481, 11482 ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe:

[issue35224] PEP 572: Assignment Expressions

Change by STINNER Victor : -- pull_requests: +11481, 11482, 11483 ___ Python tracker ___ ___ Python-bugs-list mailing list

[issue35224] PEP 572: Assignment Expressions

Change by STINNER Victor : -- pull_requests: +11481 ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe:

[issue35224] PEP 572: Assignment Expressions

Guido van Rossum added the comment: This is huge! I do recall there are some minor edge cases where the implementation currently doesn't match the PEP. Could you summarize those here, and add your recommendation (e.g. change the PEP, fix the code, wait and see) with motivation? --

[issue35224] PEP 572: Assignment Expressions

Emily Morehouse added the comment: New changeset 8f59ee01be3d83d5513a9a3f654a237d77d80d9a by Emily Morehouse in branch 'master': bpo-35224: PEP 572 Implementation (#10497) https://github.com/python/cpython/commit/8f59ee01be3d83d5513a9a3f654a237d77d80d9a --

[issue35224] PEP 572: Assignment Expressions

Change by Steven D'Aprano : -- nosy: +steven.daprano ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe:

[issue35224] PEP 572: Assignment Expressions

Change by Karthikeyan Singaravelan : -- nosy: +xtreak ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe:

[issue35224] PEP 572: Assignment Expressions

Change by Eric V. Smith : -- nosy: +eric.smith ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe:

[issue35224] PEP 572: Assignment Expressions

Change by Emily Morehouse : -- keywords: +patch pull_requests: +9758 stage: -> patch review ___ Python tracker ___ ___

[issue35224] PEP 572: Assignment Expressions

Change by Emily Morehouse : -- keywords: +patch, patch pull_requests: +9758, 9759 stage: -> patch review ___ Python tracker ___

[issue35224] PEP 572: Assignment Expressions

New submission from Emily Morehouse : This issue will serve to track development and PRs for the implementation of PEP 572: Assignment Expressions. -- assignee: emilyemorehouse components: Interpreter Core messages: 329781 nosy: emilyemorehouse, gvanrossum, tim.peters priority: normal