make wsgiref.headers.Headers accept empty constructor

[tarekziade]

BPO	5800
Nosy	@pjeby, @tarekziade, @merwok, @bitdancer, @berkerpeksag
Files	patch issue5800.diff issue5800.diff issue5800_v2.diff issue5800_v3.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 = 'https://github.com/berkerpeksag'
closed_at = <Date 2014-07-02.05:38:54.044>
created_at = <Date 2009-04-20.16:01:04.297>
labels = ['easy', 'type-feature', 'library']
title = 'make wsgiref.headers.Headers accept empty constructor'
updated_at = <Date 2014-07-02.05:38:54.043>
user = 'https://github.com/tarekziade'

bugs.python.org fields:

activity = <Date 2014-07-02.05:38:54.043>
actor = 'berker.peksag'
assignee = 'berker.peksag'
closed = True
closed_date = <Date 2014-07-02.05:38:54.044>
closer = 'berker.peksag'
components = ['Library (Lib)']
creation = <Date 2009-04-20.16:01:04.297>
creator = 'tarek'
dependencies = []
files = ['14311', '21016', '35721', '35787', '35814']
hgrepos = []
issue_num = 5800
keywords = ['patch', 'easy', 'needs review']
message_count = 26.0
messages = ['86199', '89458', '89459', '89484', '121680', '121681', '121690', '121829', '121958', '121959', '122276', '122318', '122323', '122352', '130169', '130181', '130752', '131578', '221243', '221247', '221248', '221650', '222020', '222033', '222069', '222070']
nosy_count = 10.0
nosy_names = ['pje', 'tarek', 'eric.araujo', 'r.david.murray', 'ptn', 'SilentGhost', 'BreamoreBoy', 'ramiroluz', 'python-dev', 'berker.peksag']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue5800'
versions = ['Python 3.5']

[tarekziade]

wsgiref.headers.Headers will let you manage a collection of HTTP
response headers, but the constructor forces you to provide a list:

>>> from wsgiref.headers import Headers
>>> headers = Headers([])
>>> headers.add_header('Content-Type', 'text/plain')

A logical change would be to allowed creating an empty Headers instance:

>>> from wsgiref.headers import Headers
>>> headers = Headers()
>>> headers.add_header('Content-Type', 'text/plain')

[ptn]

Patch attached. While I was at it, I also removed stupid whitespace and
generally made the module more PEP-8-compliant.

[tarekziade]

I have added another issue for PEP-8 compliancy at bpo-5801

[ptn]

Added a pointer from bpo-5801 to here.

[SilentGhost]

Correct and update patch + update test case

[SilentGhost]

here is the updated test case

[ramiroluz]

I applied the patches for wsgiref.headers and test_headers.py, ran the test with runtests.sh test_headers.py and it passed.

I also tried the code in the description:

>> from wsgiref.headers import Headers
>> headers = Headers()
>> headers.add_header('Content-Type', 'text/plain')
>>

[merwok]

FTR, note that “svn diff file1 file2...” will give you one file for many edits. It’s easier to review and apply.

Regarding the change, I don’t know if wsgiref 3.2 has to be compatible with Python 2.1, which would exclude using the ternary operation.

The change from type to isinstance will probably be rejected, since WSGI does not accept subclasses for the things it defines.

[pjeby]

Yes, please consider the type->isinstance part of the change rejected. I just got done reverting a bunch of those in 3.2. Where WSGI specifies types, it means "type() is", not "isinstance".

(The 3.x version of wsgiref does not need to be executable on 2.x versions, but this doesn't mean the protocol itself can be altered in backwards-incompatible ways, just the implementation.)

[SilentGhost]

Do I have to resubmit the patch or can you use the existing one?

[SilentGhost]

Re-submitting the patch for Lib/wsgiref/headers.py w/o the isinstance change

[SilentGhost]

Here is the correction for the docs. I would love to see this making it into 3.2 release.