namedtuple does not normalize field names when checking for duplicates

[jimjjewett]

BPO	13871
Nosy	@rhettinger, @JimJJewett

^{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/rhettinger'
closed_at = <Date 2013-07-12.06:30:34.297>
created_at = <Date 2012-01-26.05:47:41.903>
labels = ['invalid']
title = 'namedtuple does not normalize field names when checking for duplicates'
updated_at = <Date 2013-07-12.06:30:34.296>
user = 'https://github.com/JimJJewett'

bugs.python.org fields:

activity = <Date 2013-07-12.06:30:34.296>
actor = 'rhettinger'
assignee = 'rhettinger'
closed = True
closed_date = <Date 2013-07-12.06:30:34.297>
closer = 'rhettinger'
components = []
creation = <Date 2012-01-26.05:47:41.903>
creator = 'Jim.Jewett'
dependencies = []
files = []
hgrepos = []
issue_num = 13871
keywords = []
message_count = 3.0
messages = ['151997', '151998', '192923']
nosy_count = 2.0
nosy_names = ['rhettinger', 'Jim.Jewett']
pr_nums = []
priority = 'low'
resolution = 'not a bug'
stage = None
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue13871'
versions = []

[jimjjewett]

collections.namedtuple raises a ValueError if any of the field names are not valid identifiers, or are duplicates.

It does not normalize the identifiers when checking for duplicates.

(Similar issue with the typename)

>>> namedtuple("dup_fields", ["a", "a"])
Traceback (most recent call last):
  File "<pyshell#23>", line 1, in <module>
    namedtuple("dup_fields", ["a", "a"])
  File "C:\python32\lib\collections.py", line 345, in namedtuple
    raise ValueError('Encountered duplicate field name: %r' % name)
ValueError: Encountered duplicate field name: 'a'



>>> namedtuple("nfk_tester", ["a", "ª"])
Traceback (most recent call last):
  File "<pyshell#22>", line 1, in <module>
    namedtuple("nfk_tester", ["a", "ª"])
  File "C:\python32\lib\collections.py", line 365, in namedtuple
    raise SyntaxError(e.msg + ':\n\n' + class_definition)
  File "<string>", line None
SyntaxError: duplicate argument 'a' in function definition:
...

and

>>> namedtuple("justª", "ª")
Traceback (most recent call last):
  File "<pyshell#24>", line 1, in <module>
    namedtuple("justª", "ª")
  File "C:\python32\lib\collections.py", line 366, in namedtuple
    result = namespace[typename]
KeyError: 'justª'

[rhettinger]

The SyntaxError is fine. The dupcheck isn't about sanitization anyway; rather, it was part of a suite of tests designed to add a more helpful error messages than the usual ones you get if you had rolled a class by hand. I would close as "invalid" but want to think it over for a while -- we'll see how all your other normalization "bugs" resolve.

[rhettinger]

Closing this for the reasons listed above.