feat: Super reusable namespaces 🤯

Only `.name` differs between the two `EagerExpr` - so why not share?

Author: dangotbanned

narwhals/_arrow/expr.py

@@ -8,11 +8,7 @@
 
 import pyarrow.compute as pc
 
-from narwhals._arrow.expr_cat import ArrowExprCatNamespace
-from narwhals._arrow.expr_dt import ArrowExprDateTimeNamespace
-from narwhals._arrow.expr_list import ArrowExprListNamespace
 from narwhals._arrow.expr_name import ArrowExprNameNamespace
-from narwhals._arrow.expr_str import ArrowExprStringNamespace
 from narwhals._arrow.series import ArrowSeries
 from narwhals._compliant import EagerExpr
 from narwhals._expression_parsing import ExprKind
@@ -268,22 +264,6 @@ def rank(
 
     ewm_mean = not_implemented()
 
-    @property
-    def dt(self: Self) -> ArrowExprDateTimeNamespace:
-        return ArrowExprDateTimeNamespace(self)
-
-    @property
-    def str(self: Self) -> ArrowExprStringNamespace:
-        return ArrowExprStringNamespace(self)
-
-    @property
-    def cat(self: Self) -> ArrowExprCatNamespace:
-        return ArrowExprCatNamespace(self)
-
     @property
     def name(self: Self) -> ArrowExprNameNamespace:
         return ArrowExprNameNamespace(self)
-
-    @property
-    def list(self: Self) -> ArrowExprListNamespace:
-        return ArrowExprListNamespace(self)

narwhals/_arrow/expr_cat.py

@@ -0,0 +1,80 @@
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+from typing import Protocol
+
+from narwhals.utils import CompliantT_co
+from narwhals.utils import _StoresCompliant
+
+if TYPE_CHECKING:
+    from typing import Callable
+
+    from narwhals.typing import TimeUnit
+
+__all__ = [
+    "CatNamespace",
+    "DateTimeNamespace",
+    "ListNamespace",
+    "NameNamespace",
+    "StringNamespace",
+]
+
+
+class CatNamespace(_StoresCompliant[CompliantT_co], Protocol[CompliantT_co]):
+    def get_categories(self) -> CompliantT_co: ...
+
+
+class DateTimeNamespace(_StoresCompliant[CompliantT_co], Protocol[CompliantT_co]):
+    def to_string(self, format: str) -> CompliantT_co: ...  # noqa: A002
+    def replace_time_zone(self, time_zone: str | None) -> CompliantT_co: ...
+    def convert_time_zone(self, time_zone: str) -> CompliantT_co: ...
+    def timestamp(self, time_unit: TimeUnit) -> CompliantT_co: ...
+    def date(self) -> CompliantT_co: ...
+    def year(self) -> CompliantT_co: ...
+    def month(self) -> CompliantT_co: ...
+    def day(self) -> CompliantT_co: ...
+    def hour(self) -> CompliantT_co: ...
+    def minute(self) -> CompliantT_co: ...
+    def second(self) -> CompliantT_co: ...
+    def millisecond(self) -> CompliantT_co: ...
+    def microsecond(self) -> CompliantT_co: ...
+    def nanosecond(self) -> CompliantT_co: ...
+    def ordinal_day(self) -> CompliantT_co: ...
+    def weekday(self) -> CompliantT_co: ...
+    def total_minutes(self) -> CompliantT_co: ...
+    def total_seconds(self) -> CompliantT_co: ...
+    def total_milliseconds(self) -> CompliantT_co: ...
+    def total_microseconds(self) -> CompliantT_co: ...
+    def total_nanoseconds(self) -> CompliantT_co: ...
+
+
+class ListNamespace(_StoresCompliant[CompliantT_co], Protocol[CompliantT_co]):
+    def len(self) -> CompliantT_co: ...
+
+
+class NameNamespace(_StoresCompliant[CompliantT_co], Protocol[CompliantT_co]):
+    def keep(self) -> CompliantT_co: ...
+    def map(self, function: Callable[[str], str]) -> CompliantT_co: ...
+    def prefix(self, prefix: str) -> CompliantT_co: ...
+    def suffix(self, suffix: str) -> CompliantT_co: ...
+    def to_lowercase(self) -> CompliantT_co: ...
+    def to_uppercase(self) -> CompliantT_co: ...
+
+
+class StringNamespace(_StoresCompliant[CompliantT_co], Protocol[CompliantT_co]):
+    def len_chars(self) -> CompliantT_co: ...
+    def replace(
+        self, pattern: str, value: str, *, literal: bool, n: int
+    ) -> CompliantT_co: ...
+    def replace_all(
+        self, pattern: str, value: str, *, literal: bool
+    ) -> CompliantT_co: ...
+    def strip_chars(self, characters: str | None) -> CompliantT_co: ...
+    def starts_with(self, prefix: str) -> CompliantT_co: ...
+    def ends_with(self, suffix: str) -> CompliantT_co: ...
+    def contains(self, pattern: str, *, literal: bool) -> CompliantT_co: ...
+    def slice(self, offset: int, length: int | None) -> CompliantT_co: ...
+    def split(self, by: str) -> CompliantT_co: ...
+    def to_datetime(self, format: str | None) -> CompliantT_co: ...  # noqa: A002
+    def to_lowercase(self) -> CompliantT_co: ...
+    def to_uppercase(self) -> CompliantT_co: ...