GeezerVison is showing github.com — array: Add 'w' type and deprecate 'u' type. · Issue #80480 · python/cpython
array: Add 'w' type and deprecate 'u' type. #80480Description
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assignee = None
closed_at = None
created_at = <Date 2019-03-15.05:50:02.657>
labels = ['3.8', 'library']
title = "array: Deprecate 'u' type in array module"
updated_at = <Date 2020-04-23.00:47:43.731>
user = 'https://github.com/methane' bugs.python.org fields:
activity = <Date 2020-04-23.00:47:43.731>
actor = 'methane'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2019-03-15.05:50:02.657>
creator = 'methane'
dependencies = []
files = []
hgrepos = []
issue_num = 36299
keywords = ['patch']
message_count = 12.0
messages = ['337967', '338031', '338595', '338598', '338607', '338608', '338609', '338610', '338611', '367000', '367044', '367065']
nosy_count = 5.0
nosy_names = ['terry.reedy', 'ncoghlan', 'methane', 'skrah', 'serhiy.storchaka']
pr_nums = ['12497']
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = None
url = 'https://bugs.python.org/issue36299'
versions = ['Python 3.8'] Linked PRs
Activitymethane commented on Mar 15, 2019 The doc says:
'u' will be removed together with the rest of the Py_UNICODE API.
Deprecated since version 3.3, will be removed in version 4.0.
https://docs.python.org/3/library/array.html
But DeprecationWarning is not raised yet. Let's raise it.
- 3.8 -- PendingDeprecationWarning
- 3.9 -- DeprecationWarning
- 4.0 or 3.10 -- Remove it.
terryjreedy commented on Mar 15, 2019 '4.0' is a stand-in for 'sometime after 2.7.final', scheduled for Jan 2020. A Pending... for 3.8.0, scheduled for Oct 2019, seems reasonable to me. Perhaps we should have a pydev discussion for the general issue of post 2.7 removals of already deprecated items. methane commented on Mar 22, 2019 methane commented on Mar 22, 2019 changed the title [-]Deprecate 'u' type in array module[/-] [+]array: Deprecate 'u' type in array module[/+] on Mar 22, 2019skrah commented on Mar 22, 2019 I think the problem is still whether to use 'u' == UCS2 and 'w' == UCS4 like in PEP-3118.
For the project I'm currently working on I'd need these for buffer exports:
>>> from xnd import *
>>> x = xnd(["abc", "xyz"], dtype="fixed_string(10, 'utf16')")
>>> y = xnd(["abc", "xyz"], dtype="fixed_string(10, 'utf32')")
>>>
>>> memoryview(x)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: type is not supported by the buffer protocol The use case is not an array that represents a single utf16 string, but
an array *of* fixed strings with different encodings.
So x would be exported with format 'u' and y with format 'w'. skrah commented on Mar 22, 2019 Just to demonstrate what the format would look like, this is working
for an array of fixed bytes:
>>> x = xnd([b"123", b"23456"], dtype="fixed_bytes(size=10)")
>>> memoryview(x).format
'10s' So the formats in the previous message would be '10u' and '10w'. serhiy-storchaka commented on Mar 22, 2019 array('u') is not tied with the legacy Unicode C API. It is possible to use the modern wchar_t based Unicode C API for it. See bpo-36346.
There are benefits from getting rid of the legacy Unicode C API, but not from array('u'). skrah commented on Mar 22, 2019 array() uses struct module characters except for 'u'. PEP-3118 was
supposed to be implemented in the struct module.
If array() continues to use 'u', the only sensible thing would be
to remove (or rename) 'a', 'u' and 'w' from PEP-3118. skrah commented on Mar 22, 2019 The funny thing is that array() already knows this:
>>> import array
>>> a = array.array("u", "123")
>>> memoryview(a).format
'w'methane commented on Apr 22, 2020 I closed #56706 (Py_UNICODE -> Py_UCS4).
I created #63852 (Py_UNICODE -> wchar_t) instead. terryjreedy commented on Apr 22, 2020 Should this issue be closed, possibly as superseded by bpo-36346, the issue for the new PR-19653? methane commented on Apr 23, 2020 While array('u') doesn't use deprecated API with #63852, I still don't like 'u' because:
- I don't have any reason to use platform dependant wchar_t. 1
- It is not consistent with PEP-3118.
How about this plan?
- Add 'w' for Py_UCS4.
- Deprecate 'u', and remove it in the future.
Reacted by Alejandro R. Sedeño and C.A.M. Gerlach encukou commented on May 9, 2023 How about:
- Add
'w' for Py_UCS4.
- Wait until all Python versions that don't have
w reach end of life
- Deprecate
'u', and remove it in the future.
Is there a reason to rush this? methane commented on May 10, 2023 array('u') will cause bugs and almost no valid use case for it.
So waiting deprecation 5+ years seems too slow.
On the other hand, I don't hurry about removing it.
I can wait 3+ releases instead of minimum 2 releases.
My plan is:
- Add 'w' and deprecate 'u' in Python 3.13
- Remove 'u' in Python 3.16+ (Postpone removal if some users still use 'u').
changed the title [-]array: Deprecate 'u' type in array module[/-] [+]array: Add 'w' type and deprecate 'u' type.[/+] on May 10, 2023vstinner commented on Jun 6, 2023 vstinner commented on Jun 6, 2023 I dislike the fact that array.array('u') is only deprecated in the doc. I would prefer to either emit a DeprecationWarning at runtime, or remove the deprecation. See also issue #105373. I'm fine with really deprecating it if someone wants to submit a PR (@methane ?). hugovk commented on Jun 6, 2023 hugovk commented on Jun 11, 2023
array('u') will cause bugs and almost no valid use case for it. So waiting deprecation 5+ years seems too slow.
On the other hand, I don't hurry about removing it. I can wait 3+ releases instead of minimum 2 releases.
My plan is:
- Add 'w' and deprecate 'u' in Python 3.13
Done in #105242 and #95760.
- Remove 'u' in Python 3.16+ (Postpone removal if some users still use 'u').
Let's close this issue and come back to this in four years. vstinner commented on Jun 1, 2026 The array u type has been removed by the PR gh-149535.
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