Add support of copy protocol to zlib compressors and decompressors

[serhiy-storchaka]

BPO	25007
Nosy	@Yhg1s, @serhiy-storchaka, @MojoVampire, @ZackerySpytz
PRs	bpo-25007: Add copy protocol support to zlib compressors and decompressors #7940
Files	patch.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 = <Date 2018-06-27.18:07:13.045>
created_at = <Date 2015-09-05.10:42:33.328>
labels = ['3.8', 'type-feature', 'library']
title = 'Add support of copy protocol to zlib compressors and decompressors'
updated_at = <Date 2018-06-27.18:07:13.044>
user = 'https://github.com/serhiy-storchaka'

bugs.python.org fields:

activity = <Date 2018-06-27.18:07:13.044>
actor = 'serhiy.storchaka'
assignee = 'none'
closed = True
closed_date = <Date 2018-06-27.18:07:13.045>
closer = 'serhiy.storchaka'
components = ['Library (Lib)']
creation = <Date 2015-09-05.10:42:33.328>
creator = 'serhiy.storchaka'
dependencies = []
files = ['40446']
hgrepos = []
issue_num = 25007
keywords = ['patch']
message_count = 6.0
messages = ['249902', '250521', '258706', '258709', '320604', '320605']
nosy_count = 6.0
nosy_names = ['twouters', 'nadeem.vawda', 'serhiy.storchaka', 'josh.r', 'introom', 'ZackerySpytz']
pr_nums = ['7940']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue25007'
versions = ['Python 3.8']

[serhiy-storchaka]

zlib compressor and decompressor objects can be copied with the copy() method, but not with copy.copy(). It is easy to add support of copy protocol to them (just add __copy__() as an alias to copy()).

[introom]

per serhiy's suggestion, added two aliases.

[MojoVampire]

Patch looks good, but incomplete. Supporting __deepcopy__ (as a simple wrapper around __copy__ that ignores the second argument) would provide complete support.

Also, should there be tests? I mean, I assume the .copy() method itself is tested, but just to detect stupid regressions, seems like testing __copy__/deepcopy for identical behavior would be a good thing.

[serhiy-storchaka]

I agree with Josh. Needed __deepcopy__ and tests. And I think there may be problem with sharing a docstring (that includes a signature) between copy() and __copy__(). It is better to just add separate method that calls the implementation of copy().

[serhiy-storchaka]

New changeset d2cbfff by Serhiy Storchaka (Zackery Spytz) in branch 'master':
bpo-25007: Add copy protocol support to zlib compressors and decompressors (GH-7940)
d2cbfff

[serhiy-storchaka]

Thank you for your contribution Zackery!