feat: add gevent to dependencies.py, raise ImportError when it's not …

…available

py-polars/polars/dependencies.py

@@ -17,6 +17,7 @@
 _PYARROW_AVAILABLE = True
 _PYDANTIC_AVAILABLE = True
 _ZONEINFO_AVAILABLE = True
+_GEVENT_AVAILABLE = True
 
 
 class _LazyModule(ModuleType):
@@ -154,6 +155,7 @@ def _lazy_import(module_name: str) -> tuple[ModuleType, bool]:
     import dataframe_api_compat
     import deltalake
     import fsspec
+    import gevent
     import hypothesis
     import numpy
     import pandas
@@ -188,6 +190,7 @@ def _lazy_import(module_name: str) -> tuple[ModuleType, bool]:
         if sys.version_info >= (3, 9)
         else _lazy_import("backports.zoneinfo")
     )
+    gevent, _GEVENT_AVAILABLE = _lazy_import("gevent")
 
 
 @lru_cache(maxsize=None)
@@ -232,6 +235,7 @@ def _check_for_pydantic(obj: Any) -> bool:
     "pydantic",
     "pyarrow",
     "zoneinfo",
+    "gevent",
     # lazy utilities
     "_check_for_numpy",
     "_check_for_pandas",
@@ -246,4 +250,5 @@ def _check_for_pydantic(obj: Any) -> bool:
     "_PANDAS_AVAILABLE",
     "_PYARROW_AVAILABLE",
     "_ZONEINFO_AVAILABLE",
+    "_GEVENT_AVAILABLE",
 ]

py-polars/polars/utils/_async.py

@@ -2,6 +2,7 @@
 
 from typing import TYPE_CHECKING, Any, Awaitable, Generator, Generic, TypeVar
 
+from polars.dependencies import _GEVENT_AVAILABLE
 from polars.utils._wrap import wrap_df
 
 if TYPE_CHECKING:
@@ -17,6 +18,12 @@ class _GeventDataFrameResult(Generic[T]):
     __slots__ = ("_watcher", "_value", "_result")
 
     def __init__(self) -> None:
+        if not _GEVENT_AVAILABLE:
+            raise ImportError(
+                "gevent is required for using LazyFrame.collect_async(gevent=True) or"
+                "polars.collect_all_async(gevent=True)"
+            )
+
         from gevent.event import AsyncResult  # type: ignore[import]
         from gevent.hub import get_hub  # type: ignore[import]
 

py-polars/polars/utils/show_versions.py

@@ -71,6 +71,7 @@ def _get_dependency_info() -> dict[str, str]:
         "sqlalchemy",
         "xlsx2csv",
         "xlsxwriter",
+        "gevent",
     ]
     return {f"{name}:": _get_dependency_version(name) for name in opt_deps}
 

py-polars/pyproject.toml

@@ -86,6 +86,7 @@ module = [
   "xlsx2csv",
   "xlsxwriter.*",
   "zoneinfo",
+  "gevent",
 ]
 ignore_missing_imports = true
 

py-polars/tests/unit/test_async.py

@@ -5,10 +5,10 @@
 from functools import partial
 from typing import Any, Callable
 
-import gevent  # type: ignore[import]
 import pytest
 
 import polars as pl
+from polars.dependencies import gevent
 
 
 async def _aio_collect_async(raises: bool = False) -> pl.DataFrame: