NamedTuple single line declaration gives error "Too many arguments for NamedTuple() [misc] #11047

Activity

1. yesthesoup

   added

   bugmypy got something wrongmypy got something wrong

   on Sep 2, 2021
2. sobolevn commented on Sep 17, 2021

   

   sobolevn

   on Sep 17, 2021

   Member

   More actions

   Working on it. It might take some time though.

   👍React with 👍1Reacted by Lauren Campbell
3. JukkaL

   added a commit that references this issue on Sep 22, 2021

   Adds better NamedTuple error messages (#11127)

   ...

   96d7242
4. sobolevn commented on Sep 22, 2021

   

   sobolevn

   on Sep 22, 2021

   Last edited by sobolevn

   Member

   More actions

   There are multiple other bugs / missing features.

   1. fullname must be str only, right now bytes is allowed by mypy, but not cpython:

   >>> import collections
   >>> collections.namedtuple(b'custom', ['x'])
   Traceback (most recent call last):
     File "<stdin>", line 1, in <module>
     File "/Users/sobolev/.pyenv/versions/3.9.1/lib/python3.9/collections/__init__.py", line 390, in namedtuple
       raise ValueError('Type names and field names must be valid '
   ValueError: Type names and field names must be valid identifiers: "b'custom'"

   2. rename=True is not supported:

   >>> N = namedtuple(typename='N', field_names=['raise'], rename=True)
   >>> N = namedtuple(typename='N', field_names=['raise'])
   Traceback (most recent call last):
     File "<stdin>", line 1, in <module>
     File "/Users/sobolev/.pyenv/versions/3.9.1/lib/python3.9/collections/__init__.py", line 393, in namedtuple
       raise ValueError('Type names and field names cannot be a '
   ValueError: Type names and field names cannot be a keyword: 'raise'

   3. module= is not supported
5. sobolevn commented on Sep 26, 2021

   

   sobolevn

   on Sep 26, 2021

   Last edited by sobolevn

   Member

   More actions

   Status update: I am rewritting argument parsing in semanal_namedtuple completely. It was way to complicated.

   Right now I can parse all possible valid combinations of NamedTuple and its arguments.
   Something like:

   def _parse_typing_namedtuple(self, typename: str) -> NamedTupleStructure:
           """Parsing ``typing.NamedTuple()`` call.
   
           In all of the examples below arguments can be named or positional.
   
           Possible valid cases:
           1. ``N = NamedTuple('N')`` - empty namedtuple,
           2. ``N = NamedTuple('N', [('a', int)])``
           3. ``N = NamedTuple(typename='N', fields=(('a', int),))``
           4. ``N = NamedTuple('N', a=int)`` with kwargs
   
           Corner cases, but still valid:
           7. ``N = NamedTuple('N', ())``, - empty namedtuple,
              we also count ``[]`` here, ``fields`` can be named or positional
           6. ``N = NamedTuple('N', fields=None, a=int)``,
              in this case ``fields`` will not be present as a namedtuple field
           7. ``N = NamedTuple('N', None, a=int)``
           8. ``N = NamedTuple(a=int, typename='N')``
              kw-arguments can be in a different order, that's fine
   
           Everything else is considered **invalid**.
           We only accept statically known types.
           """

   🎉React with 🎉1Reacted by Lauren Campbell
6. AlexWaygood

   added

   topic-named-tuple

   semantic-analyzerProblems that happen during semantic analysisProblems that happen during semantic analysis

   on Mar 26, 2022