configparser: remove broken __name__ support

[ambv]

BPO	10489
Nosy	@freddrake, @birkenfeld, @merwok, @voidspace, @ambv
Files	issue10489.diff: Patch for removal of the broken __name__ key

^{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/ambv'
closed_at = <Date 2010-11-21.14:00:34.494>
created_at = <Date 2010-11-21.12:30:53.412>
labels = ['easy', 'type-bug', 'library']
title = 'configparser: remove broken `__name__` support'
updated_at = <Date 2010-11-21.14:00:34.492>
user = 'https://github.com/ambv'

bugs.python.org fields:

activity = <Date 2010-11-21.14:00:34.492>
actor = 'lukasz.langa'
assignee = 'lukasz.langa'
closed = True
closed_date = <Date 2010-11-21.14:00:34.494>
closer = 'lukasz.langa'
components = ['Library (Lib)']
creation = <Date 2010-11-21.12:30:53.412>
creator = 'lukasz.langa'
dependencies = []
files = ['19742']
hgrepos = []
issue_num = 10489
keywords = ['patch', 'easy', 'needs review']
message_count = 4.0
messages = ['121912', '121913', '121920', '121928']
nosy_count = 5.0
nosy_names = ['fdrake', 'georg.brandl', 'eric.araujo', 'michael.foord', 'lukasz.langa']
pr_nums = []
priority = 'normal'
resolution = 'accepted'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue10489'
versions = ['Python 3.2']

[ambv]

I want to sum up all strange things about the behaviour of __name__, a special key present in every section of a parser instance.

1. There is a special __name__ key in every section.
2. Except for the DEFAULTSECT.
3. __name__ key is set for every section read from a file.
4. and not when adding by add_section().
5. if __name__ does exist, it's not visible in parser.options('section')
6. but it is visible here: parser.has_option('section', '__name__') == True
7. and can be obtained by parser.get('section', '__name__')
8. and can be changed by parser.set('section', '__name__', 'ANY VALUE')
9. and can be removed by parser.remove_option('section', '__name__')
10. even if the value is changed by parser.set(), it won't be written back to a file with parser.write()

All this looks like a feature that was not particularly complete and well defined when it was first created. Or possibly, it became rotten with time and now nobody is using it anyway. That way or the other, I couldn't come up with a valid use case for __name__ with the current implementation. It doesn't serve any internal purpose and the only way you can actually get it is to parser.get('section', '__name__') which returns 'section' anyway. About as useless as it gets. Of course, one can go and take the internal parser._sections data structure of the parser but that's evil.

I want simply remove all mentions of a special __name__ key in configparser.py. Backwards compatibility is not a concern here because in this case we have a concept that is so broken that you can't actually use it.

[ambv]

For the record, I wrote about this problem in July on the mailing list [1], there were no replies.

[1] http://mail.python.org/pipermail/python-dev/2010-July/102556.html

[ambv]

Patch for the cleanup attached. 47 lines removed, about a half of these were in tests explicitly made to check for these inconsistencies. 4 lines added, all of them are reformattings due to removal of the other lines.

Syntax highlighted view of the patch:
http://bpaste.net/show/11395/

[ambv]

Committed in rev 86638. A public API for getting the name of the section from a SectionProxy instance was introduced in 86639. This is useful because you can assing a section proxy to a variable and pass it around:

>>> from configparser import SafeConfigParser
>>> parser = SafeConfigParser()
>>> parser.read_string("""
... [section1]
... value = A
... value2 = B
... 
... [section2]
... value = C
... value2 = D
... """)
>>> section1 = parser['section1']
>>> section1['value']
'A'
>>> section1.name
'section1'
>>> section2 = parser['section2']
>>> section2['value']
'C'
>>> section2.name
'section2'
>>> section2.name = 'cannot do that, this attribute is read-only on a SectionProxy'
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: can't set attribute