Fraction constructor may accept spaces around '/'

[skirpichev]

BPO	44346
Nosy	@mdickinson, @vedgar, @skirpichev
Files	fraction-spaces.diff

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

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GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2021-06-08.08:29:36.097>
labels = ['library', '3.11']
title = "Fraction constructor may accept spaces around '/'"
updated_at = <Date 2021-06-09.07:04:43.200>
user = 'https://github.com/skirpichev'

bugs.python.org fields:

activity = <Date 2021-06-09.07:04:43.200>
actor = 'Sergey.Kirpichev'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2021-06-08.08:29:36.097>
creator = 'Sergey.Kirpichev'
dependencies = []
files = ['50097']
hgrepos = []
issue_num = 44346
keywords = ['patch']
message_count = 5.0
messages = ['395314', '395379', '395381', '395382', '395384']
nosy_count = 3.0
nosy_names = ['mark.dickinson', 'veky', 'Sergey.Kirpichev']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = None
url = 'https://bugs.python.org/issue44346'
versions = ['Python 3.11']

[skirpichev]

Per https://bugs.python.org/msg394731 suggestion.

For instance, mpq_set_str() does support this. Also, gmpy2.mpq().

Tentative patch attached.

[vedgar]

Of course, I'm for it. But we have to be consistent... I was surprised to realize complex doesn't accept '2 + 3j' (even though it accepts '(2+3j)', and even '\n2+3j\t'). There are a lot of slippery slopes here (e.g. how about 3_j?). I think that once we allowed _ in integer literals, suddenly we could add more separation between digits than around them in many contexts, and that just seems wrong.

[skirpichev]

On Wed, Jun 09, 2021 at 06:18:22AM +0000, Vedran Čačić wrote:

I was surprised to realize complex doesn't accept '2 + 3j'

Good catch, probably that should be allowed too.

e.g. how about 3_j?

The PEP-515 added '_' as a separator between digits. But the
imaginary unit is not a digit. For same reason '1_/2' shouldn't
be allowed for the Rational constructor. (Unfortunately, the
Decimal class breaks this PEP convention as well as some other,
see bpo-44267. For example, it accepts things like '1._2'.)

[mdickinson]

I was surprised to realize complex doesn't accept '2 + 3j'

See previous discussion in bpo-9574.

[skirpichev]

See previous discussion in bpo-9574.

Given this, probably spaces around '/' should be disallowed.

[mdickinson]

Implemented in #96496.