Use version guards instead of “except ImportError” (scverse#3145)

src/scanpy/_compat.py

@@ -1,19 +1,13 @@
 from __future__ import annotations
 
+import sys
 from dataclasses import dataclass, field
-from functools import partial
+from functools import cache, partial
 from pathlib import Path
 
 from legacy_api_wrap import legacy_api
 from packaging.version import Version
 
-try:
-    from functools import cache
-except ImportError:  # Python < 3.9
-    from functools import lru_cache
-
-    cache = lru_cache(maxsize=None)
-
 try:
     from dask.array import Array as DaskArray
 except ImportError:
@@ -31,7 +25,6 @@ class ZappyArray:
 
 
 __all__ = [
-    "cache",
     "DaskArray",
     "ZappyArray",
     "fullname",
@@ -48,9 +41,9 @@ def fullname(typ: type) -> str:
     return f"{module}.{name}"
 
 
-try:
+if sys.version_info >= (3, 11):
     from contextlib import chdir
-except ImportError:  # Python < 3.11
+else:
     import os
     from contextlib import AbstractContextManager
 

src/testing/scanpy/_helpers/data.py

@@ -6,16 +6,7 @@
 from __future__ import annotations
 
 import warnings
-
-try:
-    from functools import cache
-except ImportError:  # Python < 3.9
-    from functools import lru_cache
-
-    def cache(func):
-        return lru_cache(maxsize=None)(func)
-
-
+from functools import cache
 from typing import TYPE_CHECKING
 
 import scanpy as sc