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bpo-32117: Allow tuple unpacking in return and yield statements (gh-4509) 

Iterable unpacking is now allowed without parentheses in yield and return
statements, e.g. ``yield 1, 2, 3, *rest``. Thanks to David Cuthbert for the
change and jChapman for added tests.
This commit is contained in:
David Cuthbert 2018-09-21 18:31:15 -07:00 committed by Guido van Rossum
parent 7279b5125e
commit fd97d1f1af
4 changed files with 18 additions and 6 deletions
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4
Grammar/Grammar
View File

@ -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
@ -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
Lib/test/test_grammar.py
View File

@ -824,11 +824,17 @@ class GrammarTests(unittest.TestCase):
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):
@ -981,6 +987,9 @@ class GrammarTests(unittest.TestCase):
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
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 ())")

3
Misc/NEWS.d/next/Core and Builtins/2017-11-22-15-43-14.bpo-32117.-vloh8.rst Normal file
View File

@ -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
Python/graminit.c
View File

@ -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] = {
@ -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},
@ -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"},