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bpo-32117: Allow tuple unpacking in return and yield statements #4509

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Merged
merged 6 commits into from
Sep 22, 2018
Merged

bpo-32117: Allow tuple unpacking in return and yield statements #4509

merged 6 commits into from
Sep 22, 2018

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dacut
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@dacut dacut commented Nov 22, 2017 •
edited by bedevere-bot
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This is a fix for issue 32117:

This stems from a query on StackOverflow.

Specifically, the following syntax is allowed:

def f():
    rest = (4, 5, 6)
    t = 1, 2, 3, *rest

While the following result in SyntaxError:

def g():
    rest = (4, 5, 6)
    return 1, 2, 3, *rest

def h():
    rest = (4, 5, 6)
    yield 1, 2, 3, *rest

Looking at the original commit that enabled tuple unpacking in assignment statements:
4905e80

I don't believe this difference is intentional.

https://bugs.python.org/issue32117

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@dacut dacut changed the title Allow tuple unpacking in return and yield statements Allow tuple unpacking in return and yield statements bpo-32117 Nov 22, 2017
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dacut commented Nov 22, 2017

CLA signed and awaiting review.

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dacut commented Nov 29, 2017

CLA reviewed and approved.

@serhiy-storchaka serhiy-storchaka changed the title Allow tuple unpacking in return and yield statements bpo-32117 bpo-32117: Allow tuple unpacking in return and yield statements Mar 26, 2018
@serhiy-storchaka serhiy-storchaka added the type-feature A feature request or enhancement label Mar 26, 2018
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I'm going to close and reopen to cause Travis-CI and AppVeyor to rerun the tests.

@gvanrossum gvanrossum closed this Sep 14, 2018
@gvanrossum gvanrossum reopened this Sep 14, 2018
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gvanrossum reviewed Sep 15, 2018
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Assuming @dacut is no longer interested in this PR. Jordan Chapman, can you add the test I requested and rebase, then push?

Lib/test/test_grammar.py
@@ -828,6 +834,8 @@ def g(): f((yield 1))
def g(): f((yield 1), 1)
def g(): f((yield from ()))
def g(): f((yield from ()), 1)
# Do not require parenthesis for tuple unpacking
def g(): rest = 4, 5, 6; yield 1, 2, 3, *rest
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I would add another test here to validate that this works, e.g. self.assertEqual(list(g()), [(1, 2, 3, 4, 5, 6)]).

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I was tempted to do self.assertEqual(*g(), (1, 2, 3, 4, 5, 6)), but I think we're testing enough unpacking

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dacut commented Sep 16, 2018

I am. :-) I'll add that test if Jordan doesn't beat me to it.

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I've added the test to my fork (https://github.com/jChapman/cpython) and rebased, but I don't have the ability to modify this pull request, so I am unsure how to proceed.

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Also, I checked that CLA from @jChapman was received so I'll change those labels. I'll probably wait a day before merging, in case another core dev wants to have a look and/or say.

@gvanrossum gvanrossum requested review from emilyemorehouse and removed request for asvetlov, ericvsmith, gpshead, ilevkivskyi, ncoghlan, rhettinger, skrah and a team September 17, 2018 16:01
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@gvanrossum Reminder to complete merge (it has now been 4 days)

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Merge unpacking return value support

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@brettcannon What's that trello.com link? I get "Card not found".

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I touched up the news entry slightly (made sure to thank @dacut and @jChapman 😄 ). If @gvanrossum doesn't merge this by the time I do my next sweep through my Python TODO list then I will.

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@gvanrossum the Trello card is for my private board to keep track of my TODO entries; didn't realize it left a comment. :/

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I see no reason to hold this up. Thanks @dacut for the fix and @jChapman for pinging this!

@gvanrossum gvanrossum merged commit fd97d1f into python:master Sep 22, 2018
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Well, I think the news entry should say "parentheses" instead of "parenthesis", and we need an entry in whatsnew.rst, but that can be done in a followup PR (@dacut and @jChapman, if one of you would be so kind?).

Also it's ridiculous what GitHub did to my commit message, but too late to fix now.

@jChapman jChapman mentioned this pull request Sep 22, 2018
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terryjreedy pushed a commit to terryjreedy/cpython that referenced this pull request Sep 23, 2018
@jChapman @miss-islington
bpo-32117: Iterable unpacking in return and yield documentation (pyth…
8fabae3 
…onGH-9487)

News entry clean up, added to what's new

Requested by @gvanrossum in python#4509 


https://bugs.python.org/issue32117
@gvanrossum gvanrossum mentioned this pull request Oct 18, 2019
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@gvanrossum gvanrossum gvanrossum approved these changes

@emilyemorehouse emilyemorehouse Awaiting requested review from emilyemorehouse

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@dacut @the-knights-who-say-ni @gvanrossum @jChapman @brettcannon @serhiy-storchaka @Mariatta @bedevere-bot