CLN: fix and move using_copy_on_write() helper out of internals (#50675)

pandas/_config/__init__.py

@@ -14,10 +14,12 @@
     "describe_option",
     "option_context",
     "options",
+    "using_copy_on_write",
 ]
 from pandas._config import config
 from pandas._config import dates  # pyright: ignore # noqa:F401
 from pandas._config.config import (
+    _global_config,
     describe_option,
     get_option,
     option_context,
@@ -26,3 +28,8 @@
     set_option,
 )
 from pandas._config.display import detect_console_encoding
+
+
+def using_copy_on_write():
+    _mode_options = _global_config["mode"]
+    return _mode_options["copy_on_write"] and _mode_options["data_manager"] == "block"

pandas/core/generic.py

@@ -29,7 +29,10 @@
 
 import numpy as np
 
-from pandas._config import config
+from pandas._config import (
+    config,
+    using_copy_on_write,
+)
 
 from pandas._libs import lib
 from pandas._libs.tslibs import (
@@ -158,7 +161,6 @@
     SingleArrayManager,
 )
 from pandas.core.internals.construction import mgr_to_mgr
-from pandas.core.internals.managers import using_copy_on_write
 from pandas.core.methods.describe import describe_ndframe
 from pandas.core.missing import (
     clean_fill_method,
@@ -4023,10 +4025,7 @@ def _check_setitem_copy(self, t: str = "setting", force: bool_t = False):
         df.iloc[0:5]['group'] = 'a'
 
         """
-        if (
-            config.get_option("mode.copy_on_write")
-            and config.get_option("mode.data_manager") == "block"
-        ):
+        if using_copy_on_write():
             return
 
         # return early if the check is not needed

pandas/core/internals/managers.py

@@ -15,7 +15,7 @@
 
 import numpy as np
 
-from pandas._config import config
+from pandas._config import using_copy_on_write
 
 from pandas._libs import (
     algos as libalgos,
@@ -2362,10 +2362,3 @@ def _preprocess_slice_or_indexer(
         if not allow_fill:
             indexer = maybe_convert_indices(indexer, length)
         return "fancy", indexer, len(indexer)
-
-
-_mode_options = config._global_config["mode"]
-
-
-def using_copy_on_write():
-    return _mode_options["copy_on_write"]

pandas/core/series.py

@@ -22,7 +22,10 @@
 
 import numpy as np
 
-from pandas._config import get_option
+from pandas._config import (
+    get_option,
+    using_copy_on_write,
+)
 
 from pandas._libs import (
     lib,
@@ -1263,10 +1266,7 @@ def _maybe_update_cacher(
             # for CoW, we never want to update the parent DataFrame cache
             # if the Series changed, and always pop the cached item
             elif (
-                not (
-                    get_option("mode.copy_on_write")
-                    and get_option("mode.data_manager") == "block"
-                )
+                not using_copy_on_write()
                 and len(self) == len(ref)
                 and self.name in ref.columns
             ):

scripts/validate_unwanted_patterns.py

@@ -52,6 +52,7 @@
     "_test_decorators",
     "__version__",  # check np.__version__ in compat.numpy.function
     "_arrow_dtype_mapping",
+    "_global_config",
 }