chore: add some notes on Eager(Namespace|Series)

Author: dangotbanned

narwhals/_compliant/namespace.py

@@ -33,6 +33,19 @@ class EagerNamespace(
     CompliantNamespace[EagerDataFrameT, EagerSeriesT],
     Protocol[EagerDataFrameT, EagerSeriesT],
 ):
+    # NOTE: Supporting moved ops
+    # - `self_create_expr_from_callable` -> `self._expr._from_callable`
+    # - `self_create_expr_from_series` -> `self._expr._from_series`
+    @property
+    def _expr(self) -> type[EagerExpr[EagerDataFrameT, EagerSeriesT]]: ...
+
+    # NOTE: Supporting moved ops
+    # - `self._create_series_from_scalar` -> `EagerSeries()._from_scalar`
+    #   - Was dependent on a `reference_series`, so is now an instance method
+    # - `<class>._from_iterable` -> `self._series._from_iterable`
+    @property
+    def _series(self) -> type[EagerSeriesT]: ...
+
     def all_horizontal(
         self, *exprs: EagerExpr[EagerDataFrameT, EagerSeriesT]
     ) -> EagerExpr[EagerDataFrameT, EagerSeriesT]: ...

narwhals/_compliant/series.py

@@ -39,10 +39,19 @@ class EagerSeries(CompliantSeries, Protocol[NativeSeriesT_co]):
     @property
     def native(self) -> NativeSeriesT_co: ...
 
+    # NOTE: `ArrowSeries` needs to intercept `value` w/
+    # if self._backend_version < (13,) and hasattr(value, "as_py"):
+    #     value = value.as_py()  # noqa: ERA001
     def _from_scalar(self, value: Any) -> Self:
         return self._from_iterable([value], name=self.name, context=self)
 
     @classmethod
     def _from_iterable(
         cls: type[Self], data: Iterable[Any], name: str, *, context: _FullContext
     ) -> Self: ...
+
+    # TODO @dangotbanned: replacing `Namespace._create_compliant_series``
+    # - All usage within `*Expr.map_batches`
+    #   - `PandasLikeExpr` uses that **once**
+    #   - `ArrowExpr` uses **twice**
+    # - `PandasLikeDataFrame.with_row_index` uses the wrapped `utils` function once