Skip to content

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

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 6 commits into from
Sep 22, 2018
Merged

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

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
6 commits
Select commit Hold shift + click to select a range
53ffbdd
Fix return statements to allow unpacking without parenthesis.
dacut Nov 16, 2017
02bd4f0
Fix yield statements to allow unpacking without parenthesis.
dacut Nov 22, 2017
47e3ac3
Add test for yield tuple unpacking.
dacut Nov 22, 2017
31a0c8f
Add news blurb for yield and return tuple unpacking.
dacut Nov 22, 2017
f84da46
Add equality test for tuple unpacking in yield
jChapman Sep 16, 2018
67303ca
Touch up news entry
brettcannon Sep 21, 2018
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
4 changes: 2 additions & 2 deletions Grammar/Grammar
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -50,7 +50,7 @@ pass_stmt: 'pass'
flow_stmt: break_stmt | continue_stmt | return_stmt | raise_stmt | yield_stmt
break_stmt: 'break'
continue_stmt: 'continue'
return_stmt: 'return' [testlist]
return_stmt: 'return' [testlist_star_expr]
yield_stmt: yield_expr
raise_stmt: 'raise' [test ['from' test]]
import_stmt: import_name | import_from
Expand Down Expand Up @@ -147,4 +147,4 @@ comp_if: 'if' test_nocond [comp_iter]
encoding_decl: NAME

yield_expr: 'yield' [yield_arg]
yield_arg: 'from' test | testlist
yield_arg: 'from' test | testlist_star_expr
11 changes: 10 additions & 1 deletion Lib/test/test_grammar.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -824,11 +824,17 @@ def test_inner(extra_burning_oil = 1, count=0):
test_inner()

def test_return(self):
# 'return' [testlist]
# 'return' [testlist_star_expr]
def g1(): return
def g2(): return 1
def g3():
z = [2, 3]
return 1, *z

g1()
x = g2()
y = g3()
self.assertEqual(y, (1, 2, 3), "unparenthesized star expr return")
check_syntax_error(self, "class foo:return 1")

def test_break_in_finally(self):
Expand Down Expand Up @@ -981,6 +987,9 @@ 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
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I would add another test here to validate that this works, e.g. self.assertEqual(list(g()), [(1, 2, 3, 4, 5, 6)]).

Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

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

self.assertEquals(list(g()), [(1, 2, 3, 4, 5, 6)])
check_syntax_error(self, "def g(): f(yield 1)")
check_syntax_error(self, "def g(): f(yield 1, 1)")
check_syntax_error(self, "def g(): f(yield from ())")
Expand Down
3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Core and Builtins/2017-11-22-15-43-14.bpo-32117.-vloh8.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,3 @@
Iterable unpacking is now allowed without parenthesis in yield and return
statements, e.g. ``yield 1, 2, 3, *rest``. Thanks to David Cuthbert for the
change and jChapman for added tests.
6 changes: 3 additions & 3 deletions Python/graminit.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -613,7 +613,7 @@ static arc arcs_25_0[1] = {
{75, 1},
};
static arc arcs_25_1[2] = {
{9, 2},
{47, 2},
{0, 1},
};
static arc arcs_25_2[1] = {
Expand Down Expand Up @@ -1900,7 +1900,7 @@ static state states_85[3] = {
};
static arc arcs_86_0[2] = {
{77, 1},
{9, 2},
{47, 2},
};
static arc arcs_86_1[1] = {
{26, 2},
Expand Down Expand Up @@ -2087,7 +2087,7 @@ static dfa dfas[87] = {
{341, "yield_expr", 0, 3, states_85,
"\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\200\000"},
{342, "yield_arg", 0, 3, states_86,
"\000\040\200\000\000\000\000\000\000\040\010\000\000\000\020\002\000\300\220\050\037\000\000"},
"\000\040\200\000\002\000\000\000\000\040\010\000\000\000\020\002\000\300\220\050\037\000\000"},
};
static label labels[177] = {
{0, "EMPTY"},
Expand Down