return_type -> eager_backend

narwhals/_duckdb/dataframe.py

@@ -81,19 +81,21 @@ def __getitem__(self, item: str) -> DuckDBInterchangeSeries:
         )
 
     @overload
-    def collect(self, return_type: Literal["pyarrow"] = "pyarrow") -> ArrowDataFrame: ...
+    def collect(
+        self, eager_backend: Literal["pyarrow"] = "pyarrow"
+    ) -> ArrowDataFrame: ...
 
     @overload
-    def collect(self, return_type: Literal["pandas"]) -> PandasLikeDataFrame: ...
+    def collect(self, eager_backend: Literal["pandas"]) -> PandasLikeDataFrame: ...
 
     @overload
-    def collect(self, return_type: Literal["polars"]) -> PolarsDataFrame: ...
+    def collect(self, eager_backend: Literal["polars"]) -> PolarsDataFrame: ...
 
     def collect(
         self,
-        return_type: Literal["pyarrow", "pandas", "polars"] = "pyarrow",
+        eager_backend: Literal["pyarrow", "pandas", "polars"] = "pyarrow",
     ) -> ArrowDataFrame | PandasLikeDataFrame | PolarsDataFrame:
-        if return_type == "pyarrow":
+        if eager_backend == "pyarrow":
             try:
                 import pyarrow as pa  # ignore-banned-import
             except ModuleNotFoundError as exc:  # pragma: no cover
@@ -110,7 +112,7 @@ def collect(
                 version=self._version,
             )
 
-        elif return_type == "pandas":
+        elif eager_backend == "pandas":
             import pandas as pd  # ignore-banned-import
 
             from narwhals._pandas_like.dataframe import PandasLikeDataFrame
@@ -123,7 +125,7 @@ def collect(
                 version=self._version,
             )
 
-        elif return_type == "polars":
+        elif eager_backend == "polars":
             import polars as pl  # ignore-banned-import
 
             from narwhals._polars.dataframe import PolarsDataFrame
@@ -137,8 +139,8 @@ def collect(
 
         else:
             msg = (
-                "Only the following `return_type`'s are supported: pyarrow, pandas and "
-                f"polars. Found '{return_type}'."
+                "Only the following `eager_backend`'s are supported: pyarrow, pandas and "
+                f"polars. Found '{eager_backend}'."
             )
             raise ValueError(msg)
 

narwhals/dataframe.py

@@ -3633,7 +3633,7 @@ def collect(
             duckdb_kwargs: Allows to specify in which eager backend to materialize a
                 DuckDBPyRelation backed LazyFrame. It is possible to choose among
                 `pyarrow`, `pandas` or `polars` by declaring
-                `duckdb_kwargs={"return_type": "<eager_backend>"}`.
+                `duckdb_kwargs={"eager_backend": "<eager_backend>"}`.
 
         Returns:
             DataFrame

narwhals/stable/v1/__init__.py

@@ -436,7 +436,7 @@ def collect(
             duckdb_kwargs: Allows to specify in which eager backend to materialize a
                 DuckDBPyRelation backed LazyFrame. It is possible to choose among
                 `pyarrow`, `pandas` or `polars` by declaring
-                `duckdb_kwargs={"return_type": "<eager_backend>"}`.
+                `duckdb_kwargs={"eager_backend": "<eager_backend>"}`.
 
         Returns:
             DataFrame

tests/frame/collect_test.py

@@ -23,7 +23,7 @@ def test_collect_kwargs(constructor: Constructor) -> None:
         .collect(
             polars_kwargs={"no_optimization": True},
             dask_kwargs={"optimize_graph": False},
-            duckdb_kwargs={"return_type": "pyarrow"},
+            duckdb_kwargs={"eager_backend": "pyarrow"},
         )
     )
 
@@ -32,23 +32,23 @@ def test_collect_kwargs(constructor: Constructor) -> None:
 
 
 @pytest.mark.parametrize(
-    ("return_type", "expected_cls"),
+    ("eager_backend", "expected_cls"),
     [
         ("pyarrow", pa.Table),
         ("polars", pl.DataFrame),
         ("pandas", pd.DataFrame),
     ],
 )
 def test_collect_duckdb(
-    return_type: Literal["pyarrow", "polars", "pandas"], expected_cls: type
+    eager_backend: Literal["pyarrow", "polars", "pandas"], expected_cls: type
 ) -> None:
     duckdb = pytest.importorskip("duckdb")
 
     data = {"a": [1, 2], "b": [3, 4]}
     df_pl = pl.DataFrame(data)  # noqa: F841
     df = nw.from_native(duckdb.sql("select * from df_pl"))
 
-    result = df.lazy().collect(duckdb_kwargs={"return_type": return_type}).to_native()
+    result = df.lazy().collect(duckdb_kwargs={"eager_backend": eager_backend}).to_native()
     assert isinstance(result, expected_cls)
 
 
@@ -62,8 +62,8 @@ def test_collect_duckdb_raise() -> None:
     with pytest.raises(
         ValueError,
         match=(
-            "Only the following `return_type`'s are supported: pyarrow, pandas and "
+            "Only the following `eager_backend`'s are supported: pyarrow, pandas and "
             "polars. Found 'foo'."
         ),
     ):
-        df.lazy().collect(duckdb_kwargs={"return_type": "foo"})
+        df.lazy().collect(duckdb_kwargs={"eager_backend": "foo"})