[issue23091] unpacked keyword arguments are not unicode normalized

[S. Andrew Sheppard]

S. Andrew Sheppard added the comment:

Fair enough.  For future reference by anyone coming across this issue, here's a 
simplified version of the workaround I used:

from unicodedata import normalize
def normalize_keys(data):
return {
normalize('NFKC', key): value
for key, value in data.items()
}

def test(μ):
print(μ)

>>> test(**normalize_keys({'µ': "test4"}))
test4

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[issue23091] unpacked keyword arguments are not unicode normalized

[Benjamin Peterson]

Benjamin Peterson added the comment:

Yeah, kwarg dicts do not have the same checks applied to them as syntactic 
keyword args. It would be weird if, for example, dict(**mydict) normalized the 
keys of mydict.

--
nosy: +benjamin.peterson
resolution:  -> not a bug
status: open -> closed

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[issue23091] unpacked keyword arguments are not unicode normalized

[R. David Murray]

R. David Murray added the comment:

I suspect that the normalization is happening in the parsing phase.  That is, 
the keyword argument gets normalized when the python source is compiled, but 
the dictionary key is, of course, *not* normalized, since it is a literal 
string.  If I'm right, I think is not a bug.

--
nosy: +r.david.murray

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[issue23091] unpacked keyword arguments are not unicode normalized

[S. Andrew Sheppard]

S. Andrew Sheppard added the comment:

Here's a simple namedtuple example for good measure.

from collections import namedtuple
Test = namedtuple("Test", [chr(181)])

>>> Test(**{chr(956): "test1"})
Test(µ='test1')

>>> Test(**{chr(181): "test1"})
Traceback (most recent call last):
  File "", line 1, in 
TypeError: __new__() got an unexpected keyword argument 'µ'

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[issue23091] unpacked keyword arguments are not unicode normalized

[S. Andrew Sheppard]

New submission from S. Andrew Sheppard:

I came across unexpected behavior working with unpacking keyword arguments in 
Python 3.  It appears to be related to the automatic normalization of unicode 
characters to NFKC (PEP 3131), which converts e.g. MICRO SIGN to GREEK SMALL 
LETTER MU.  This conversion is applied to regular keyword arguments but not 
when unpacking arguments via **.

This issue arose while I was working with some automatically generated 
namedtuple classes, but I was able to reproduce it with a simple function:

def test(μ):
print(μ)

>>> test(µ="test1") # chr(181)
test1

>>> test(μ="test2") # chr(956)
test2

>>> test(**{'μ': "test3"}) # chr(956)
test3

>>> test(**{'µ': "test4"}) # chr(181)

Traceback (most recent call last):
  File "", line 1, in 
TypeError: test() got an unexpected keyword argument 'µ'


I can obviously work around this, but wanted to bring it up in case it's a bug. 
 My naive expectation would be that unpacked ** keys should be treated exactly 
like normal keyword arguments.

--
components: Unicode
messages: 232956
nosy: ezio.melotti, haypo, sheppard
priority: normal
severity: normal
status: open
title: unpacked keyword arguments are not unicode normalized
versions: Python 3.4

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