C API of OrderedDict

[serhiy-storchaka]

BPO	29084
Nosy	@brettcannon, @rhettinger, @ericsnowcurrently, @serhiy-storchaka
PRs	bpo-29084: Exclude C API for OrderedDict from the limited C API. #4900 [3.6] bpo-29084: Exclude C API for OrderedDict from the limited C API. (GH-4900) #5007

^{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 = 'https://github.com/serhiy-storchaka'
closed_at = <Date 2017-12-25.07:41:02.690>
created_at = <Date 2016-12-27.13:59:17.756>
labels = ['interpreter-core']
title = 'C API of OrderedDict'
updated_at = <Date 2017-12-25.07:41:02.689>
user = 'https://github.com/serhiy-storchaka'

bugs.python.org fields:

activity = <Date 2017-12-25.07:41:02.689>
actor = 'serhiy.storchaka'
assignee = 'serhiy.storchaka'
closed = True
closed_date = <Date 2017-12-25.07:41:02.690>
closer = 'serhiy.storchaka'
components = ['Interpreter Core']
creation = <Date 2016-12-27.13:59:17.756>
creator = 'serhiy.storchaka'
dependencies = []
files = []
hgrepos = []
issue_num = 29084
keywords = ['patch']
message_count = 7.0
messages = ['284098', '284115', '284175', '286014', '308463', '309020', '309030']
nosy_count = 4.0
nosy_names = ['brett.cannon', 'rhettinger', 'eric.snow', 'serhiy.storchaka']
pr_nums = ['4900', '5007']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue29084'
versions = []

[serhiy-storchaka]

C API of the C implementation of OrderedDict was added in 3.5 together with the C implementation of OrderedDict. But it was never announced nor documented. Some macros contain bugs. PyODict_Check() and PyODict_CheckExact() are declared in the limited API, but don't work since use PyODict_Type not available in the limited API. PyODict_SIZE() is expanded to syntactically incorrect code and it's name is not consistent with similar macros: PyTuple_GET_SIZE, PyList_GET_SIZE and just added PyDict_GET_SIZE. Many names are just transparent wrappers around PyDict API (and they can't be different).

Since PyODict C API is not documented, partially not working and partially redundant, and the C implementation of OrderedDict is optional (other Python implementations can provide just Python implementation of OrderedDict), I think this C API should be made private if not removed.

[brettcannon]

If the API is broken in the limited API then I definitely think we should consistently make it not part of the limited API. As for removing it I don't have an opinion without knowing how many people are using it.

[rhettinger]

+1 for privatizing

[serhiy-storchaka]

Eric, what are your thoughts?

[rhettinger]

With today's announcement of guaranteed ordering for regular dicts, OrderedDict just became much less important (almost insignificant). Also, the original reason for having this C API no longer applies.

There is a reasonable case to be made for removing the API entirely (given that it was never documented, that it is buggy, and that it is no longer of any significance).

[serhiy-storchaka]

New changeset 1b3029a by Serhiy Storchaka in branch 'master':
bpo-29084: Exclude C API for OrderedDict from the limited C API. (bpo-4900)
1b3029a

[serhiy-storchaka]

New changeset d62b741 by Serhiy Storchaka (Miss Islington (bot)) in branch '3.6':
bpo-29084: Exclude C API for OrderedDict from the limited C API. (GH-4900) (bpo-5007)
d62b741