refactor(expr-ir): Generate dispatch methods

narwhals/_plan/arrow/dataframe.py

@@ -9,7 +9,7 @@
 from narwhals._plan.arrow import functions as fn
 from narwhals._plan.arrow.series import ArrowSeries
 from narwhals._plan.common import ExprIR
-from narwhals._plan.protocols import EagerDataFrame
+from narwhals._plan.protocols import EagerDataFrame, namespace
 from narwhals._utils import Version
 
 if t.TYPE_CHECKING:
@@ -89,7 +89,7 @@ def to_dict(
         return {ser.name: ser.to_list() for ser in it}
 
     def _evaluate_irs(self, nodes: Iterable[NamedIR[ExprIR]], /) -> Iterator[ArrowSeries]:
-        ns = self.__narwhals_namespace__()
+        ns = namespace(self)
         from_named_ir = ns._expr.from_named_ir
         yield from ns._expr.align(from_named_ir(e, self) for e in nodes)
 

narwhals/_plan/arrow/expr.py

@@ -11,7 +11,7 @@
 from narwhals._plan.arrow.series import ArrowSeries
 from narwhals._plan.arrow.typing import NativeScalar, StoresNativeT_co
 from narwhals._plan.common import ExprIR, NamedIR, into_dtype
-from narwhals._plan.protocols import EagerExpr, EagerScalar, ExprDispatch
+from narwhals._plan.protocols import EagerExpr, EagerScalar, ExprDispatch, namespace
 from narwhals._utils import (
     Implementation,
     Version,
@@ -245,8 +245,8 @@ def sort_by(self, node: expr.SortBy, frame: ArrowDataFrame, name: str) -> ArrowE
             self._dispatch_expr(e, frame, f"<TEMP>_{idx}")
             for idx, e in enumerate(node.by)
         )
-        ns = self.__narwhals_namespace__()
-        df = ns._concat_horizontal((series, *by))
+
+        df = namespace(self)._concat_horizontal((series, *by))
         names = df.columns[1:]
         indices = pc.sort_indices(df.native, options=node.options.to_arrow(names))
         result: ChunkedArrayAny = df.native.column(0).take(indices)

narwhals/_plan/protocols.py

@@ -70,6 +70,14 @@
 LazyScalarT_co = TypeVar("LazyScalarT_co", bound=LazyScalarAny, covariant=True)
 
 
+def namespace(obj: _SupportsNarwhalsNamespace[NamespaceT_co], /) -> NamespaceT_co:
+    return obj.__narwhals_namespace__()
+
+
+class _SupportsNarwhalsNamespace(Protocol[NamespaceT_co]):
+    def __narwhals_namespace__(self) -> NamespaceT_co: ...
+
+
 # NOTE: Unlike the version in `nw._utils`, here `.version` it is public
 class StoresVersion(Protocol):
     _version: Version
@@ -144,15 +152,13 @@ def _length_required(
 
 class ExprDispatch(StoresVersion, Protocol[FrameT_contra, R_co, NamespaceT_co]):
     _DISPATCH: ClassVar[Mapping[type[ExprIR], Callable[[Any, ExprIR, Any, str], Any]]] = {
-        expr.Column: lambda self, node, frame, name: self.__narwhals_namespace__().col(
+        expr.Column: lambda self, node, frame, name: namespace(self).col(
             node, frame, name
         ),
-        expr.Literal: lambda self, node, frame, name: self.__narwhals_namespace__().lit(
-            node, frame, name
-        ),
-        expr.Len: lambda self, node, frame, name: self.__narwhals_namespace__().len(
+        expr.Literal: lambda self, node, frame, name: namespace(self).lit(
             node, frame, name
         ),
+        expr.Len: lambda self, node, frame, name: namespace(self).len(node, frame, name),
         expr.Cast: lambda self, node, frame, name: self.cast(node, frame, name),
         expr.Sort: lambda self, node, frame, name: self.sort(node, frame, name),
         expr.SortBy: lambda self, node, frame, name: self.sort_by(node, frame, name),
@@ -185,10 +191,9 @@ class ExprDispatch(StoresVersion, Protocol[FrameT_contra, R_co, NamespaceT_co]):
         ),
         # NOTE: Keeping it simple for now
         # When adding other `*_range` functions, this should instead map to `range_expr`
-        expr.RangeExpr: lambda self,
-        node,
-        frame,
-        name: self.__narwhals_namespace__().int_range(node, frame, name),
+        expr.RangeExpr: lambda self, node, frame, name: namespace(self).int_range(
+            node, frame, name
+        ),
         expr.OrderedWindowExpr: lambda self, node, frame, name: self.over_ordered(
             node, frame, name
         ),
@@ -200,34 +205,27 @@ class ExprDispatch(StoresVersion, Protocol[FrameT_contra, R_co, NamespaceT_co]):
     _DISPATCH_FUNCTION: ClassVar[
         Mapping[type[Function], Callable[[Any, FunctionExpr, Any, str], Any]]
     ] = {
-        boolean.AnyHorizontal: lambda self,
-        node,
-        frame,
-        name: self.__narwhals_namespace__().any_horizontal(node, frame, name),
-        boolean.AllHorizontal: lambda self,
-        node,
-        frame,
-        name: self.__narwhals_namespace__().all_horizontal(node, frame, name),
-        F.SumHorizontal: lambda self,
-        node,
-        frame,
-        name: self.__narwhals_namespace__().sum_horizontal(node, frame, name),
-        F.MinHorizontal: lambda self,
-        node,
-        frame,
-        name: self.__narwhals_namespace__().min_horizontal(node, frame, name),
-        F.MaxHorizontal: lambda self,
-        node,
-        frame,
-        name: self.__narwhals_namespace__().max_horizontal(node, frame, name),
-        F.MeanHorizontal: lambda self,
-        node,
-        frame,
-        name: self.__narwhals_namespace__().mean_horizontal(node, frame, name),
-        strings.ConcatHorizontal: lambda self,
-        node,
-        frame,
-        name: self.__narwhals_namespace__().concat_str(node, frame, name),
+        boolean.AnyHorizontal: lambda self, node, frame, name: namespace(
+            self
+        ).any_horizontal(node, frame, name),
+        boolean.AllHorizontal: lambda self, node, frame, name: namespace(
+            self
+        ).all_horizontal(node, frame, name),
+        F.SumHorizontal: lambda self, node, frame, name: namespace(self).sum_horizontal(
+            node, frame, name
+        ),
+        F.MinHorizontal: lambda self, node, frame, name: namespace(self).min_horizontal(
+            node, frame, name
+        ),
+        F.MaxHorizontal: lambda self, node, frame, name: namespace(self).max_horizontal(
+            node, frame, name
+        ),
+        F.MeanHorizontal: lambda self, node, frame, name: namespace(self).mean_horizontal(
+            node, frame, name
+        ),
+        strings.ConcatHorizontal: lambda self, node, frame, name: namespace(
+            self
+        ).concat_str(node, frame, name),
         F.Pow: lambda self, node, frame, name: self.pow(node, frame, name),
         F.FillNull: lambda self, node, frame, name: self.fill_null(node, frame, name),
         boolean.IsBetween: lambda self, node, frame, name: self.is_between(
@@ -704,12 +702,10 @@ class EagerDataFrame(
 ):
     def __narwhals_namespace__(self) -> EagerNamespace[Self, SeriesT, Any, Any]: ...
     def select(self, irs: Seq[NamedIR]) -> Self:
-        ns = self.__narwhals_namespace__()
-        return ns._concat_horizontal(self._evaluate_irs(irs))
+        return self.__narwhals_namespace__()._concat_horizontal(self._evaluate_irs(irs))
 
     def with_columns(self, irs: Seq[NamedIR]) -> Self:
-        ns = self.__narwhals_namespace__()
-        return ns._concat_horizontal(self._evaluate_irs(irs))
+        return self.__narwhals_namespace__()._concat_horizontal(self._evaluate_irs(irs))
 
 
 class CompliantSeries(StoresVersion, Protocol[NativeSeriesT]):