[GitHub] [beam] ssjhv commented on issue #23366: [Bug]: Python Runtime Type Introspection Mishandles PEP 585 Generics

["ssjhv (via GitHub)" <gi...@apache.org>]

ssjhv commented on issue #23366:
URL: https://github.com/apache/beam/issues/23366#issuecomment-1472675930

   Is PEP-585 supposed to be fully handled now? I noticed that imports from `collections.abc` raised typehint errors.
   
   Example:
   ```python
   from collections.abc import Iterator
   import apache_beam as beam
   
   def add_range(n: int) -> Iterator[int]:
     for i in range(n):
       yield i
   
   with beam.Pipeline() as p:
       numbers = p | "Create" >> beam.Create([1, 2, 3, 4, 5])
       numbers = numbers | beam.FlatMap(add_range)
       _ = numbers | beam.combiners.Count.PerElement() | beam.Map(print
   ```
   
   ```
   ---------------------------------------------------------------------------
   ValueError                                Traceback (most recent call last)
   /usr/local/lib/python3.9/dist-packages/apache_beam/transforms/core.py in default_type_hints(self)
       959     try:
   --> 960       type_hints = type_hints.strip_iterable()
       961     except ValueError as e:
   
   9 frames
   ValueError: collections.abc.Iterator[int] is not iterable
   
   During handling of the above exception, another exception occurred:
   
   TypeCheckError                            Traceback (most recent call last)
   /usr/local/lib/python3.9/dist-packages/apache_beam/transforms/core.py in default_type_hints(self)
       960       type_hints = type_hints.strip_iterable()
       961     except ValueError as e:
   --> 962       raise TypeCheckError(
       963           'Return value not iterable: %s: %s' %
       964           (self.display_data()['fn'].value, e))
   
   TypeCheckError: Return value not iterable: add_range: collections.abc.Iterator[int] is not iterable
   ```


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