Negative values in positional access inside formatting

[facundobatista]

BPO	33160
Nosy	@facundobatista, @ericvsmith
Superseder	bpo-7951: Should str.format allow negative indexes when used for getitem access?

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

Show more details

GitHub fields:

assignee = None
closed_at = <Date 2018-03-27.21:43:24.292>
created_at = <Date 2018-03-27.21:07:48.690>
labels = ['type-feature', '3.8']
title = 'Negative values in positional access inside formatting'
updated_at = <Date 2018-03-27.21:43:24.291>
user = 'https://github.com/facundobatista'

bugs.python.org fields:

activity = <Date 2018-03-27.21:43:24.291>
actor = 'serhiy.storchaka'
assignee = 'none'
closed = True
closed_date = <Date 2018-03-27.21:43:24.292>
closer = 'serhiy.storchaka'
components = []
creation = <Date 2018-03-27.21:07:48.690>
creator = 'facundobatista'
dependencies = []
files = []
hgrepos = []
issue_num = 33160
keywords = []
message_count = 1.0
messages = ['314549']
nosy_count = 2.0
nosy_names = ['facundobatista', 'eric.smith']
pr_nums = []
priority = 'normal'
resolution = 'duplicate'
stage = 'resolved'
status = 'closed'
superseder = '7951'
type = 'enhancement'
url = 'https://bugs.python.org/issue33160'
versions = ['Python 3.8']

[facundobatista]

This works fine:

>>> "{[0]}".format([1, 2, 3])
'1'

This should work too:

>>> "{[-1]}".format([1, 2, 3])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: list indices must be integers or slices, not str