[
https://issues.apache.org/jira/browse/FLINK-39578?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Florian Vazelle updated FLINK-39578:
------------------------------------
Description:
PyFlink currently does not include a {{py.typed}} marker file in its
distributed wheel. As a result, static type checkers like {{mypy}} treat the
package as untyped, even though type annotations are present in the source code.
This prevents users from benefiting from type checking when using PyFlink, as
{{mypy}} ignores inline type hints unless the package explicitly declares
itself as typed per [PEP 561|https://peps.python.org/pep-0561/].
*Steps to Reproduce:*
{code:bash}
$ uv init test
$ cd test/
$ uv add apache-flink
$ uv add mypy --group dev
{code}
Edit the {{{}main.py{}}}:
{code:python}
from pyflink.datastream.functions import FlatMapFunction
class Filter(FlatMapFunction):
def flat_map(self, event):
if event:
yield event
{code}
{code:bash}
$ uv run mypy .
main.py:1: error: Skipping analyzing "pyflink.datastream.functions": module is
installed, but missing library stubs or py.typed marker [import-untyped]
main.py:1: note: See
https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
{code}
*Expected Behavior:*
PyFlink should be recognized as a typed package, allowing mypy to analyze its
type annotations.
*Suggested Fix:*
Include an empty {{py.typed}} file in the pyflink package and ensure it is
packaged in the wheel.
was:
PyFlink currently does not include a {{{{{}py.typed{}}}}} marker file in its
distributed wheel. As a result, static type checkers like {{mypy}} treat the
package as untyped, even though type annotations are present in the source code.
This prevents users from benefiting from type checking when using PyFlink, as
{{mypy}} ignores inline type hints unless the package explicitly declares
itself as typed per [PEP 561|https://peps.python.org/pep-0561/].
*Steps to Reproduce:*
{code:java}
uv init test
cd test/
$ uv add apache-flink
$ uv add mypy --group dev
{code}
Edit the main.py:
{code:java}
from pyflink.datastream.functions import FlatMapFunction
class Filter(FlatMapFunction):
def flat_map(self, event):
if event:
yield event
{code}
{code:java}
$ uv run mypy .
main.py:1: error: Skipping analyzing "pyflink.datastream.functions": module is
installed, but missing library stubs or py.typed marker [import-untyped]
main.py:1: note: See
https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports{code}
> Missing py.typed in PyFlink wheel prevents type checking with mypy
> ------------------------------------------------------------------
>
> Key: FLINK-39578
> URL: https://issues.apache.org/jira/browse/FLINK-39578
> Project: Flink
> Issue Type: Bug
> Components: API / Python
> Reporter: Florian Vazelle
> Priority: Minor
>
> PyFlink currently does not include a {{py.typed}} marker file in its
> distributed wheel. As a result, static type checkers like {{mypy}} treat the
> package as untyped, even though type annotations are present in the source
> code.
> This prevents users from benefiting from type checking when using PyFlink, as
> {{mypy}} ignores inline type hints unless the package explicitly declares
> itself as typed per [PEP 561|https://peps.python.org/pep-0561/].
> *Steps to Reproduce:*
> {code:bash}
> $ uv init test
> $ cd test/
> $ uv add apache-flink
> $ uv add mypy --group dev
> {code}
> Edit the {{{}main.py{}}}:
> {code:python}
> from pyflink.datastream.functions import FlatMapFunction
> class Filter(FlatMapFunction):
> def flat_map(self, event):
> if event:
> yield event
> {code}
> {code:bash}
> $ uv run mypy .
> main.py:1: error: Skipping analyzing "pyflink.datastream.functions": module
> is installed, but missing library stubs or py.typed marker [import-untyped]
> main.py:1: note: See
> https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
> {code}
> *Expected Behavior:*
> PyFlink should be recognized as a typed package, allowing mypy to analyze its
> type annotations.
> *Suggested Fix:*
> Include an empty {{py.typed}} file in the pyflink package and ensure it is
> packaged in the wheel.
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