[New-bugs-announce] [issue32626] Subscript unpacking raises SyntaxError

[Ben Burrill]

New submission from Ben Burrill <bburrill98 at gmail.com>:

PEP 448 defines unpacking generalizations for tuples.  However, this does not currently work for subscripted tuples that are not delimited by parentheses.

Current behavior (Tested on 3.6/3.7a4):
>>> class Subscriptable:
...     def __getitem__(self, item):
...         return item
...
>>> ss = Subscriptable()
>>> 
>>> 1, 2, 3
(1, 2, 3)
>>> ss[1, 2, 3]
(1, 2, 3)
>>> *range(5), 42
(0, 1, 2, 3, 4, 42)
>>> ss[*range(5), 42]  # This should be the same as above
  File "<stdin>", line 1
    ss[*range(5), 42]
       ^
SyntaxError: invalid syntax
>>> ss[(*range(5), 42)]  # Workaround
(0, 1, 2, 3, 4, 42)

----------
components: Interpreter Core
messages: 310447
nosy: Ben Burrill
priority: normal
severity: normal
status: open
title: Subscript unpacking raises SyntaxError
type: behavior
versions: Python 3.7

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue32626>
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