DEPR: Nonkeyword arguments in to_pickle (#54599)

* deprecated non keyword arguments

* addressed review comments

Author: rsm-23

doc/source/whatsnew/v2.2.0.rst

@@ -92,7 +92,7 @@ Other API changes
 
 Deprecations
 ~~~~~~~~~~~~
--
+- Deprecated allowing non-keyword arguments in :meth:`DataFrame.to_pickle` except ``path``. (:issue:`54229`)
 -
 
 .. ---------------------------------------------------------------------------

pandas/core/generic.py

@@ -3017,6 +3017,9 @@ def to_sql(
         )
 
     @final
+    @deprecate_nonkeyword_arguments(
+        version="3.0", allowed_args=["self", "path"], name="to_pickle"
+    )
     @doc(
         storage_options=_shared_docs["storage_options"],
         compression_options=_shared_docs["compression_options"] % "path",

pandas/tests/io/test_pickle.py

@@ -585,3 +585,15 @@ def test_pickle_frame_v124_unpickle_130(datapath):
 
     expected = pd.DataFrame(index=[], columns=[])
     tm.assert_frame_equal(df, expected)
+
+
+def test_pickle_pos_args_deprecation():
+    # GH-54229
+    df = pd.DataFrame({"a": [1, 2, 3]})
+    msg = (
+        r"Starting with pandas version 3.0 all arguments of to_pickle except for the "
+        r"argument 'path' will be keyword-only."
+    )
+    with tm.assert_produces_warning(FutureWarning, match=msg):
+        buffer = io.BytesIO()
+        df.to_pickle(buffer, "infer")