DEPR: **kwargs in ExcelWriter

doc/source/whatsnew/v1.3.0.rst

@@ -369,6 +369,7 @@ Deprecations
 - Deprecated casting ``datetime.date`` objects to ``datetime64`` when used as ``fill_value`` in :meth:`DataFrame.unstack`, :meth:`DataFrame.shift`, :meth:`Series.shift`, and :meth:`DataFrame.reindex`, pass ``pd.Timestamp(dateobj)`` instead (:issue:`39767`)
 - Deprecated :meth:`.Styler.set_na_rep` and :meth:`.Styler.set_precision` in favour of :meth:`.Styler.format` with ``na_rep`` and ``precision`` as existing and new input arguments respectively (:issue:`40134`)
 - Deprecated allowing partial failure in :meth:`Series.transform` and :meth:`DataFrame.transform` when ``func`` is list-like or dict-like; will raise if any function fails on a column in a future version (:issue:`40211`)
+- Deprecated the use of ``**kwargs`` in :class:`.ExcelWriter`; use the keyword argument ``engine_kwargs`` instead (:issue:`40430`)
 
 .. ---------------------------------------------------------------------------
 

pandas/io/excel/_base.py

@@ -667,6 +667,14 @@ class ExcelWriter(metaclass=abc.ABCMeta):
         be parsed by ``fsspec``, e.g., starting "s3://", "gcs://".
 
         .. versionadded:: 1.2.0
+    engine_kwargs : dict, optional
+        Keyword arguments to be passed into the engine.
+    **kwargs : dict, optional
+        Keyword arguments to be passed into the engine.
+
+        .. deprecated:: 1.3.0
+
+            Use engine_kwargs instead.
 
     Attributes
     ----------
@@ -745,7 +753,26 @@ class ExcelWriter(metaclass=abc.ABCMeta):
     # You also need to register the class with ``register_writer()``.
     # Technically, ExcelWriter implementations don't need to subclass
     # ExcelWriter.
-    def __new__(cls, path, engine=None, **kwargs):
+    def __new__(
+        cls,
+        path: Union[FilePathOrBuffer, ExcelWriter],
+        engine=None,
+        date_format=None,
+        datetime_format=None,
+        mode: str = "w",
+        storage_options: StorageOptions = None,
+        engine_kwargs: Optional[Dict] = None,
+        **kwargs,
+    ):
+        if kwargs:
+            if engine_kwargs is not None:
+                raise ValueError("Cannot use both engine_kwargs and **kwargs")
+            warnings.warn(
+                "Use of **kwargs is deprecated, use engine_kwargs instead.",
+                FutureWarning,
+                stacklevel=2,
+            )
+
         # only switch class if generic(ExcelWriter)
 
         if cls is ExcelWriter:
@@ -835,7 +862,8 @@ def __init__(
         datetime_format=None,
         mode: str = "w",
         storage_options: StorageOptions = None,
-        **engine_kwargs,
+        engine_kwargs: Optional[Dict] = None,
+        **kwargs,
     ):
         # validate that this engine can handle the extension
         if isinstance(path, str):

pandas/io/excel/_odswriter.py

@@ -26,19 +26,22 @@ def __init__(
         self,
         path: str,
         engine: Optional[str] = None,
+        date_format=None,
+        datetime_format=None,
         mode: str = "w",
         storage_options: StorageOptions = None,
-        **engine_kwargs,
+        engine_kwargs: Optional[Dict[str, Any]] = None,
     ):
         from odf.opendocument import OpenDocumentSpreadsheet
 
-        engine_kwargs["engine"] = engine
-
         if mode == "a":
             raise ValueError("Append mode is not supported with odf!")
 
         super().__init__(
-            path, mode=mode, storage_options=storage_options, **engine_kwargs
+            path,
+            mode=mode,
+            storage_options=storage_options,
+            engine_kwargs=engine_kwargs,
         )
 
         self.book = OpenDocumentSpreadsheet()

pandas/io/excel/_openpyxl.py

@@ -3,6 +3,7 @@
 import mmap
 from typing import (
     TYPE_CHECKING,
+    Any,
     Dict,
     List,
     Optional,
@@ -35,15 +36,20 @@ def __init__(
         self,
         path,
         engine=None,
+        date_format=None,
+        datetime_format=None,
         mode: str = "w",
         storage_options: StorageOptions = None,
-        **engine_kwargs,
+        engine_kwargs: Optional[Dict[str, Any]] = None,
     ):
         # Use the openpyxl module as the Excel writer.
         from openpyxl.workbook import Workbook
 
         super().__init__(
-            path, mode=mode, storage_options=storage_options, **engine_kwargs
+            path,
+            mode=mode,
+            storage_options=storage_options,
+            engine_kwargs=engine_kwargs,
         )
 
         # ExcelWriter replaced "a" by "r+" to allow us to first read the excel file from

pandas/io/excel/_xlsxwriter.py

@@ -1,6 +1,8 @@
 from typing import (
+    Any,
     Dict,
     List,
+    Optional,
     Tuple,
 )
 
@@ -175,11 +177,13 @@ def __init__(
         datetime_format=None,
         mode: str = "w",
         storage_options: StorageOptions = None,
-        **engine_kwargs,
+        engine_kwargs: Optional[Dict[str, Any]] = None,
     ):
         # Use the xlsxwriter module as the Excel writer.
         from xlsxwriter import Workbook
 
+        engine_kwargs = engine_kwargs or {}
+
         if mode == "a":
             raise ValueError("Append mode is not supported with xlsxwriter!")
 
@@ -190,7 +194,7 @@ def __init__(
             datetime_format=datetime_format,
             mode=mode,
             storage_options=storage_options,
-            **engine_kwargs,
+            engine_kwargs=engine_kwargs,
         )
 
         self.book = Workbook(self.handles.handle, **engine_kwargs)

pandas/io/excel/_xlwt.py

@@ -1,6 +1,8 @@
 from typing import (
     TYPE_CHECKING,
+    Any,
     Dict,
+    Optional,
 )
 
 import pandas._libs.json as json
@@ -21,21 +23,24 @@ def __init__(
         self,
         path,
         engine=None,
+        date_format=None,
+        datetime_format=None,
         encoding=None,
         mode: str = "w",
         storage_options: StorageOptions = None,
-        **engine_kwargs,
+        engine_kwargs: Optional[Dict[str, Any]] = None,
     ):
         # Use the xlwt module as the Excel writer.
         import xlwt
 
-        engine_kwargs["engine"] = engine
-
         if mode == "a":
             raise ValueError("Append mode is not supported with xlwt!")
 
         super().__init__(
-            path, mode=mode, storage_options=storage_options, **engine_kwargs
+            path,
+            mode=mode,
+            storage_options=storage_options,
+            engine_kwargs=engine_kwargs,
         )
 
         if encoding is None:

pandas/tests/io/excel/test_writers.py

@@ -6,6 +6,7 @@
 from functools import partial
 from io import BytesIO
 import os
+import re
 
 import numpy as np
 import pytest
@@ -1382,6 +1383,25 @@ def check_called(func):
             with tm.ensure_clean("something.xls") as filepath:
                 check_called(lambda: df.to_excel(filepath, engine="dummy"))
 
+    @pytest.mark.parametrize(
+        "ext",
+        [
+            pytest.param(".xlsx", marks=td.skip_if_no("xlsxwriter")),
+            pytest.param(".xlsx", marks=td.skip_if_no("openpyxl")),
+            pytest.param(".ods", marks=td.skip_if_no("odf")),
+        ],
+    )
+    def test_kwargs_deprecated(self, ext):
+        # GH 40430
+        msg = re.escape("Use of **kwargs is deprecated")
+        with tm.assert_produces_warning(FutureWarning, match=msg):
+            with tm.ensure_clean(ext) as path:
+                try:
+                    with ExcelWriter(path, kwarg=1):
+                        pass
+                except TypeError:
+                    pass
+
 
 @td.skip_if_no("xlrd")
 @td.skip_if_no("openpyxl")