mock.patch could whitelist builtins to not need create=True

[voidspace]

BPO	17660
Nosy	@pitrou, @merwok, @voidspace, @berkerpeksag, @kushaldas
Files	issue17660.patch: initial patch issue17660_v3.patch: Updated patch with builtins module.

^{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/voidspace'
closed_at = <Date 2014-04-14.20:25:31.121>
created_at = <Date 2013-04-08.10:48:09.957>
labels = ['easy', 'type-bug', 'library']
title = 'mock.patch could whitelist builtins to not need create=True'
updated_at = <Date 2014-04-15.19:28:37.514>
user = 'https://github.com/voidspace'

bugs.python.org fields:

activity = <Date 2014-04-15.19:28:37.514>
actor = 'eric.araujo'
assignee = 'michael.foord'
closed = True
closed_date = <Date 2014-04-14.20:25:31.121>
closer = 'python-dev'
components = ['Library (Lib)']
creation = <Date 2013-04-08.10:48:09.957>
creator = 'michael.foord'
dependencies = []
files = ['29731', '34825']
hgrepos = []
issue_num = 17660
keywords = ['patch', 'easy']
message_count = 11.0
messages = ['186290', '186291', '186301', '186323', '186347', '215917', '216113', '216201', '216360', '216364', '216366']
nosy_count = 6.0
nosy_names = ['pitrou', 'eric.araujo', 'michael.foord', 'python-dev', 'berker.peksag', 'kushal.das']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue17660'
versions = ['Python 3.5']

[voidspace]

When patching builtin names (e.g. open) in a specific namespace you need to specify "create=True" or patch will refuse to create a name that doesn't exist.

patch could whitelist the builtin names, when the patch target is a module object, to not require the "create=True".

[kushaldas]

Working on this.

[kushaldas]

Initial patchset along with documentation and tests update.

[pitrou]

To be honest this proposal sounds like a quirk more than a feature to me. If you only special-case builtins, people will have to remember that special case and it will make the API more complicated.

[voidspace]

I don't think that's a particular issue. In general you only need to use "create=True" if a name is *not* available in a namespace.

Builtin names are odd in that you can use them in a namespace even though they don't exist there - so you have to *remember* to use "create=True" even though the name *is* available.

So this issue is about fixing that quirk.

[merwok]

Reviewed on Rietveld.

[kushaldas]

Updated patch with builtins module.

[python-dev]

New changeset e457de60028c by Michael Foord in branch 'default':
Closes bpo-17660. You no longer need to explicitly pass create=True when patching builtin names.
http://hg.python.org/cpython/rev/e457de60028c

[berkerpeksag]

+ .. note::

I think using a note directive is not necessary here. Also it looks a bit ugly :) https://dl.dropboxusercontent.com/u/166024/issue17660.png

•    .. versionchanged:: 3.5
  

•       If you are patching builtins in a module then you don't
  

•       need to pass `create=True`, it will be added by default.
  

[voidspace]

Personally I don't think it looks ugly and that it is a point worth calling out. Other opinions welcomed.