SpooledTemporaryFile.seek returns None

[amcinnes]

BPO	40287
Nosy	@methane, @miss-islington
PRs	bpo-40287: Fix SpooledTemporaryFile.seek() return value #19540 [3.8] bpo-40287: Fix SpooledTemporaryFile.seek() return value (GH-19540) #19566 [3.7] bpo-40287: Fix SpooledTemporaryFile.seek() return value (GH-19540) #19567

^{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 = <Date 2020-04-17.07:15:52.468>
created_at = <Date 2020-04-15.01:41:51.263>
labels = ['3.7', '3.8', 'type-bug', 'library', '3.9']
title = 'SpooledTemporaryFile.seek returns None'
updated_at = <Date 2020-04-17.07:15:52.460>
user = 'https://bugs.python.org/amcinnes'

bugs.python.org fields:

activity = <Date 2020-04-17.07:15:52.460>
actor = 'methane'
assignee = 'none'
closed = True
closed_date = <Date 2020-04-17.07:15:52.468>
closer = 'methane'
components = ['Library (Lib)']
creation = <Date 2020-04-15.01:41:51.263>
creator = 'amcinnes'
dependencies = []
files = []
hgrepos = []
issue_num = 40287
keywords = ['patch']
message_count = 4.0
messages = ['366475', '366643', '366644', '366645']
nosy_count = 3.0
nosy_names = ['methane', 'miss-islington', 'amcinnes']
pr_nums = ['19540', '19566', '19567']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue40287'
versions = ['Python 3.7', 'Python 3.8', 'Python 3.9']

[amcinnes]

The documentation says SpooledTemporaryFile "operates exactly as TemporaryFile() does".

seek() would be expected to return the new absolute position; this is what it does for TemporaryFile, and is the documented behaviour of seek() in IOBase. But for SpooledTemporaryFile it returns None.

Probably trivial to fix by sticking a "return" on

cpython/Lib/tempfile.py

Line 741 in 0361556

self._file.seek(*args)

Python 3.8.2 (default, Apr  8 2020, 14:31:25) 
[GCC 9.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import tempfile
>>> t = tempfile.TemporaryFile()
>>> print(t.seek(0))
0
>>> u = tempfile.SpooledTemporaryFile()
>>> print(u.seek(0))
None
>>>

[methane]

New changeset 485e715 by Inada Naoki in branch 'master':
bpo-40287: Fix SpooledTemporaryFile.seek() return value (GH-19540)
485e715

[miss-islington]

New changeset 11ae7d0 by Miss Islington (bot) in branch '3.7':
bpo-40287: Fix SpooledTemporaryFile.seek() return value (GH-19540)
11ae7d0

[miss-islington]

New changeset 9796fe8 by Miss Islington (bot) in branch '3.8':
bpo-40287: Fix SpooledTemporaryFile.seek() return value (GH-19540)
9796fe8