address review

python/cudf/cudf/core/dataframe.py

@@ -8080,7 +8080,7 @@ def value_counts(
         return result
 
     @_performance_tracking
-    def to_pylibcudf(self, copy=False):
+    def to_pylibcudf(self, copy: bool = False) -> tuple[plc.Table, dict]:
         """
         Convert this DataFrame to a pylibcudf.Table.
 
@@ -8114,16 +8114,14 @@ def to_pylibcudf(self, copy=False):
         """
         if copy:
             raise NotImplementedError("copy=True is not supported")
-        metadata = {}
-        metadata["index"] = self.index
-        metadata["column_names"] = self.columns
+        metadata = {"index": self.index, "columns": self.columns}
         return plc.Table(
             [col.to_pylibcudf(mode="write") for col in self._columns]
         ), metadata
 
     @classmethod
     @_performance_tracking
-    def from_pylibcudf(cls, table: plc.Table, metadata: dict):
+    def from_pylibcudf(cls, table: plc.Table, metadata: dict) -> Self:
         """
         Create a DataFrame from a pylibcudf.Table.
 
@@ -8148,19 +8146,20 @@ def from_pylibcudf(cls, table: plc.Table, metadata: dict):
         the data and mask buffers of the pylibcudf columns, so the newly created
         object is not tied to the lifetime of the original pylibcudf.Table.
         """
-        if metadata is None:
+        if not isinstance(metadata, dict):
             raise ValueError("Must at least pass metadata with column names")
         columns = table.columns()
         df = cls._from_data(
             {
                 name: cudf.core.column.ColumnBase.from_pylibcudf(
                     col, data_ptr_exposed=True
                 )
-                for name, col in zip(metadata["column_names"], columns)
+                for name, col in zip(metadata["columns"], columns)
             }
         )
         for key in metadata:
-            setattr(df, key, metadata[key])
+            if key in {"index", "columns"}:
+                setattr(df, key, metadata[key])
         return df
 
 

python/cudf/cudf/core/series.py

@@ -3845,7 +3845,7 @@ def to_pylibcudf(self, copy=False) -> tuple[plc.Column, dict]:
 
     @classmethod
     @_performance_tracking
-    def from_pylibcudf(cls, col: plc.Column, metadata=None):
+    def from_pylibcudf(cls, col: plc.Column, metadata=None) -> Self:
         """
         Create a Series from a pylibcudf.Column.
 
@@ -3871,7 +3871,7 @@ def from_pylibcudf(cls, col: plc.Column, metadata=None):
                 col, data_ptr_exposed=True
             )
         )
-        if metadata:
+        if isinstance(metadata, dict):
             for key in metadata:
                 setattr(cudf_col, key, metadata[key])
         return cudf_col

python/cudf/cudf/tests/test_dataframe.py

@@ -11258,6 +11258,5 @@ def test_dataframe_multiindex_column_names(names):
 @pytest.mark.parametrize("pdf", _dataframe_na_data())
 def test_roundtrip_dataframe_plc_table(pdf):
     expect = cudf.DataFrame.from_pandas(pdf)
-    plc_table, metadata = expect.to_pylibcudf()
-    actual = cudf.DataFrame.from_pylibcudf(plc_table, metadata=metadata)
+    actual = cudf.DataFrame.from_pylibcudf(*expect.to_pylibcudf())
     assert_eq(expect, actual)

python/cudf/cudf/tests/test_series.py

@@ -3008,6 +3008,5 @@ def test_dtype_dtypes_equal():
 @pytest.mark.parametrize("ps", _series_na_data())
 def test_roundtrip_series_plc_column(ps):
     expect = cudf.Series(ps)
-    plc_col, metadata = expect.to_pylibcudf()
-    actual = cudf.Series.from_pylibcudf(plc_col, metadata=metadata)
+    actual = cudf.Series.from_pylibcudf(*expect.to_pylibcudf())
     assert_eq(expect, actual)