generate_async type annotation does not support `.aclose()`

Question

generate_async type annotation does not support `.aclose()`

graingert opened this issue 3 months ago · comments

given:

import contextlib
import sys
import trio
from collections.abc import AsyncGenerator

from jinja2 import Template, select_autoescape


class MyModel:
    class objects:
        @staticmethod
        async def all() -> AsyncGenerator[str, None]:
            while True:
                yield "hello"


template = """
<html>
  <head></head>
  <body>
    {% for m in model.objects.all() %}
        {{ m }}
        {% break %}
    {% endfor %}
  </body>
</html>
"""


async def amain() -> None:
    agen = Template(
        source=template, enable_async=True, extensions=["jinja2.ext.loopcontrols"]
    ).generate_async(model=MyModel)
    async for v in agen:
        print(v)
        break


def main() -> int | None:
    return trio.run(amain)


if __name__ == "__main__":
    sys.exit(main())

it outputs:

python -Wall demo_jinja_asyncgens.py 

<html>
  <head></head>
  <body>
    
/home/graingert/.virtualenvs/demo-jinja-asyncgens/lib/python3.12/site-packages/trio/_core/_run.py:2599: ResourceWarning: Async generator 'jinja2.environment.Template.generate_async' was garbage collected before it had been exhausted. Surround its use in 'async with aclosing(...):' to ensure that it gets cleaned up as soon as you're done using it.
  msg = task.context.run(next_send_fn, next_send)
ResourceWarning: Enable tracemalloc to get the object allocation traceback
/home/graingert/.virtualenvs/demo-jinja-asyncgens/lib/python3.12/site-packages/jinja2/environment.py:1371: ResourceWarning: Async generator '<<template>>.root' was garbage collected before it had been exhausted. Surround its use in 'async with aclosing(...):' to ensure that it gets cleaned up as soon as you're done using it.
  yield event
ResourceWarning: Enable tracemalloc to get the object allocation traceback

following the instructions in mypy results in:

demo_jinja_asyncgens.py:31: error: Value of type variable "_SupportsAcloseT" of "aclosing" cannot be "AsyncIterator[str]" [type-var]