made changes for issue 41485, set_codes function

Author: Pydare

pandas/core/indexes/multi.py

@@ -41,6 +41,7 @@
 from pandas.util._decorators import (
     Appender,
     cache_readonly,
+    deprecate_nonkeyword_arguments,
     doc,
 )
 
@@ -994,6 +995,7 @@ def _set_codes(
 
         self._reset_cache()
 
+    @deprecate_nonkeyword_arguments(version=None, allowed_args=["self", "codes"])
     def set_codes(self, codes, level=None, inplace=None, verify_integrity: bool = True):
         """
         Set new codes on MultiIndex. Defaults to returning new index.

pandas/tests/indexes/multi/test_get_set.py

@@ -405,3 +405,32 @@ def test_set_levels_inplace_deprecated(idx, inplace):
 
     with tm.assert_produces_warning(FutureWarning):
         idx.set_levels(levels=new_level, level=1, inplace=inplace)
+
+
+def test_set_codes_pos_args_depreciation():
+    # https://github.com/pandas-dev/pandas/issues/41485
+    idx = MultiIndex.from_tuples(
+        [
+            (1, "one"),
+            (1, "two"),
+            (2, "one"),
+            (2, "two"),
+        ],
+        names=["foo", "bar"]
+    )
+    msg = (
+        r"In a future version of pandas all arguments of MultiIndex.set_codes except"
+        r"for the argument 'codes' will be keyword-only"
+    )
+    with tm.assert_produces_warning(FutureWarning, match=msg):
+        result = idx.set_codes([[1, 0, 1, 0], [0, 0, 1, 1]])
+    expected = MultiIndex.from_tuples(
+        [
+            (2, "one"), 
+            (1, "one"), 
+            (2, "two"), 
+            (1, "two"),
+        ],
+        names=["foo", "bar"]
+    )
+    tm.assert_index_equal(result, expected)