mattalbr opened a new issue, #33802:
URL: https://github.com/apache/beam/issues/33802
### What would you like to happen?
It would be awesome for the following code to work (written in 3.12 syntax,
but would be great in <=3.11 syntax too)
```
T = TypeVar("T")
@dataclass.dataclass()
class NeatOutputClass[T]:
data: T
class ReusableTransform[T](beam.PTransform):
def __init__(self, value_extractor: Callable[[Any], T):
# This is a bit contrived, but not unreasonable for a transform acting
# on slightly different data. Could be done as a generic DoFn too.
self.value_extractor = value_extractor
def expand(self, pcoll: beam.PCollection) -> NeatOutputClass[T]:
# Overly simplified for simple reproducibility.
return pcoll | beam.Map(lambda x: self.value_extractor(x))
```
But unfortunately this yields `TypeError: Subscripted generics cannot be
used with class and instance checks`
<details>
<summary>Full Stack Trace</summary>
```py
/home/vscode/.cache/pants/named_caches/pex_root/venvs/s/192fb705/venv/lib/python3.11/site-packages/apache_beam/transforms/ptransform.py:622:
in __ror__
result = p.apply(self, pvalueish, label)
/home/vscode/.cache/pants/named_caches/pex_root/venvs/s/192fb705/venv/lib/python3.11/site-packages/apache_beam/pipeline.py:754:
in apply
pvalueish_result = self.runner.apply(transform, pvalueish, self._options)
/home/vscode/.cache/pants/named_caches/pex_root/venvs/s/192fb705/venv/lib/python3.11/site-packages/apache_beam/runners/runner.py:191:
in apply
return self.apply_PTransform(transform, input, options)
/home/vscode/.cache/pants/named_caches/pex_root/venvs/s/192fb705/venv/lib/python3.11/site-packages/apache_beam/runners/runner.py:195:
in apply_PTransform
return transform.expand(input)
my_repo/transformation.py:263: in expand
pcolls
/home/vscode/.cache/pants/named_caches/pex_root/venvs/s/192fb705/venv/lib/python3.11/site-packages/apache_beam/transforms/ptransform.py:622:
in __ror__
result = p.apply(self, pvalueish, label)
/home/vscode/.cache/pants/named_caches/pex_root/venvs/s/192fb705/venv/lib/python3.11/site-packages/apache_beam/pipeline.py:757:
in apply
transform.type_check_outputs(pvalueish_result)
/home/vscode/.cache/pants/named_caches/pex_root/venvs/s/192fb705/venv/lib/python3.11/site-packages/apache_beam/transforms/ptransform.py:475:
in type_check_outputs
self.type_check_inputs_or_outputs(pvalueish, 'output')
/home/vscode/.cache/pants/named_caches/pex_root/venvs/s/192fb705/venv/lib/python3.11/site-packages/apache_beam/transforms/ptransform.py:496:
in type_check_inputs_or_outputs
if hint and not typehints.is_consistent_with(pvalue_.element_type, hint):
/home/vscode/.cache/pants/named_caches/pex_root/venvs/s/192fb705/venv/lib/python3.11/site-packages/apache_beam/typehints/typehints.py:1323:
in is_consistent_with
return base._consistent_with_check_(sub)
/home/vscode/.cache/pants/named_caches/pex_root/venvs/s/192fb705/venv/lib/python3.11/site-packages/apache_beam/typehints/typehints.py:711:
in _consistent_with_check_
len(sub.tuple_types) == len(self.tuple_types) and all(
/home/vscode/.cache/pants/named_caches/pex_root/venvs/s/192fb705/venv/lib/python3.11/site-packages/apache_beam/typehints/typehints.py:712:
in <genexpr>
is_consistent_with(sub_elem, elem) for sub_elem,
/home/vscode/.cache/pants/named_caches/pex_root/venvs/s/192fb705/venv/lib/python3.11/site-packages/apache_beam/typehints/typehints.py:1323:
in is_consistent_with
return base._consistent_with_check_(sub)
/home/vscode/.cache/pants/named_caches/pex_root/venvs/s/192fb705/venv/lib/python3.11/site-packages/apache_beam/typehints/typehints.py:271:
in _consistent_with_check_
is_consistent_with(sub.inner_type, self.inner_type))
/home/vscode/.cache/pants/named_caches/pex_root/venvs/s/192fb705/venv/lib/python3.11/site-packages/apache_beam/typehints/typehints.py:1329:
in is_consistent_with
return issubclass(sub, base)
```
</details>
### Issue Priority
Priority: 2 (default / most feature requests should be filed as P2)
### Issue Components
- [x] Component: Python SDK
- [ ] Component: Java SDK
- [ ] Component: Go SDK
- [ ] Component: Typescript SDK
- [ ] Component: IO connector
- [ ] Component: Beam YAML
- [ ] Component: Beam examples
- [ ] Component: Beam playground
- [ ] Component: Beam katas
- [ ] Component: Website
- [ ] Component: Infrastructure
- [ ] Component: Spark Runner
- [ ] Component: Flink Runner
- [ ] Component: Samza Runner
- [ ] Component: Twister2 Runner
- [ ] Component: Hazelcast Jet Runner
- [ ] Component: Google Cloud Dataflow Runner
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