UCS4 support functions are not implemented

[serhiy-storchaka]

BPO	29087
Nosy	@malemburg, @vstinner, @benjaminp, @ezio-melotti, @serhiy-storchaka

^{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 2016-12-28.07:20:58.049>
created_at = <Date 2016-12-27.19:13:23.545>
labels = ['type-bug', '3.7', 'expert-unicode', 'docs']
title = 'UCS4 support functions are not implemented'
updated_at = <Date 2016-12-28.07:20:58.048>
user = 'https://github.com/serhiy-storchaka'

bugs.python.org fields:

activity = <Date 2016-12-28.07:20:58.048>
actor = 'serhiy.storchaka'
assignee = 'docs@python'
closed = True
closed_date = <Date 2016-12-28.07:20:58.049>
closer = 'serhiy.storchaka'
components = ['Documentation', 'Unicode']
creation = <Date 2016-12-27.19:13:23.545>
creator = 'serhiy.storchaka'
dependencies = []
files = []
hgrepos = []
issue_num = 29087
keywords = []
message_count = 5.0
messages = ['284126', '284141', '284142', '284156', '284157']
nosy_count = 7.0
nosy_names = ['lemburg', 'vstinner', 'benjamin.peterson', 'ezio.melotti', 'docs@python', 'python-dev', 'serhiy.storchaka']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue29087'
versions = ['Python 3.5', 'Python 3.6', 'Python 3.7']

[serhiy-storchaka]

There is a special section in the documentation of Unicode Objects C API: UCS4 Support.

https://docs.python.org/3/c-api/unicode.html#ucs4-support

It documents utility functions that work on strings of Py_UCS4 characters like Py_UCS4_strlen(), Py_UCS4_strcpy(), etc. But none of these functions is implemented. May be the documentation should be just removed?

[vstinner]

I recall that the very first implementation of the PEP-393 (compact strings) was heavily based on UCS4. Slowly, I optimized the code by specializing functions to each kind of string (ACSII, Latin1, UCS2, UCS4).

[vstinner]

Py_UCS4_strlen() added by:

changeset: 72475:8beaa9a37387
user: Martin v. Löwis <martin@v.loewis.de>
date: Wed Sep 28 07:41:54 2011 +0200
files: ...
description:
Implement PEP-393.

Removed by:

changeset: 73236:80a7ab9ac29f
user: Martin v. Löwis <martin@v.loewis.de>
date: Mon Oct 31 08:40:56 2011 +0100
files: Include/unicodeobject.h Objects/unicodeobject.c Objects/uniops.h
description:
Drop Py_UCS4_ functions. Closes bpo-13246.

80a7ab9ac29f came before Python 3.3.0:

haypo@selma$ hg log -r v3.3.0
changeset: 79242:bd8afb90ebf2
branch: 3.3
tag: v3.3.0
parent: 79237:cb84dcb35114
user: Georg Brandl <georg@python.org>
date: Sat Sep 29 09:44:17 2012 +0200
files: Lib/test/test_sys.py
description:
Fix test_sys.test_implementation for final releases.

Py_UCS4_strlen() was documented but was never part of any public Python release.

=> you can remove the doc.

[python-dev]

New changeset 29d46d29e169 by Serhiy Storchaka in branch '3.5':
Issue bpo-29087: Removed the documentation of non-existing UCS4 support functions.
https://hg.python.org/cpython/rev/29d46d29e169

New changeset e44b6b01c8cf by Serhiy Storchaka in branch '3.6':
Issue bpo-29087: Removed the documentation of non-existing UCS4 support functions.
https://hg.python.org/cpython/rev/e44b6b01c8cf

New changeset 0ec4befef7e0 by Serhiy Storchaka in branch 'default':
Issue bpo-29087: Removed the documentation of non-existing UCS4 support functions.
https://hg.python.org/cpython/rev/0ec4befef7e0

[serhiy-storchaka]

Thanks Victor.