add a function for get_component

src/kfactory/layout.py

@@ -67,7 +67,7 @@
     get_cell_name,
 )
 from .settings import Info, KCellSettings, KCellSettingsUnits
-from .typings import K, KCellParams, MetaData, T
+from .typings import K, KCellParams, KCellSpec, MetaData, T
 from .utilities import load_layout_options, save_layout_options
 
 kcl: KCLayout
@@ -1638,6 +1638,61 @@ def get_dcross_section(
     def __repr__(self) -> str:
         return f"{self.__class__.__name__}({self.name}, n={len(self.kcells)})"
 
+    @overload
+    def get_component(
+        self, spec: KCellSpec, *, output_type: type[K], **cell_kwargs: Any
+    ) -> K: ...
+
+    @overload
+    def get_component(
+        self,
+        spec: int,
+    ) -> KCell: ...
+
+    @overload
+    def get_component(
+        self,
+        spec: str,
+        **cell_kwargs: Any,
+    ) -> ProtoTKCell[Any]: ...
+
+    @overload
+    def get_component(
+        self,
+        spec: Callable[..., K],
+        **cell_kwargs: Any,
+    ) -> K: ...
+    @overload
+    def get_component(self, spec: K) -> K: ...
+
+    def get_component(
+        self,
+        spec: KCellSpec,
+        *,
+        output_type: type[K] | None = None,
+        **cell_kwargs: Any,
+    ) -> ProtoTKCell[Any]:
+        if output_type:
+            return output_type(base=self.get_component(spec, **cell_kwargs).base)
+        if callable(spec):
+            return spec(**cell_kwargs)
+        if isinstance(spec, dict):
+            settings = spec.get("settings", {}).copy()
+            settings.update(cell_kwargs)
+            return self.factories[spec["component"]](**settings)
+        elif isinstance(spec, str):
+            return self.factories[spec](**cell_kwargs)
+        if cell_kwargs:
+            raise ValueError(
+                "Cell kwargs are not allowed for retrieving static cells by integer "
+                "or the cell itself."
+            )
+        if isinstance(spec, int):
+            c: ProtoTKCell[Any] = self.kcells[spec]
+        else:
+            c = spec
+        return c
+
 
 KCLayout.model_rebuild()
 TVCell.model_rebuild()

src/kfactory/typings.py

@@ -1,6 +1,16 @@
 from __future__ import annotations
 
-from typing import TYPE_CHECKING, Annotated, Any, ParamSpec, TypeAlias, TypeVar
+from collections.abc import Callable
+from typing import (
+    TYPE_CHECKING,
+    Annotated,
+    Any,
+    NotRequired,
+    ParamSpec,
+    TypeAlias,
+    TypedDict,
+    TypeVar,
+)
 
 import klayout.db as kdb
 import klayout.lay as lay
@@ -12,7 +22,6 @@
     from .layout import Constants
     from .port import ProtoPort
 
-
 T = TypeVar("T")
 K = TypeVar("K", bound="ProtoTKCell[Any]")
 KC = TypeVar("KC", bound="ProtoTKCell[Any]", covariant=True)
@@ -26,6 +35,12 @@
 TBaseCell = TypeVar("TBaseCell", bound="BaseKCell", covariant=True)
 KCellParams = ParamSpec("KCellParams")
 
+
+class KCellSpecDict(TypedDict):
+    component: str
+    settings: NotRequired[dict[str, Any]]
+
+
 AnyTrans = TypeVar(
     "AnyTrans", bound=kdb.Trans | kdb.DTrans | kdb.ICplxTrans | kdb.DCplxTrans
 )
@@ -106,3 +121,6 @@
 """Database unit or micrometer."""
 Angle: TypeAlias = int
 """Integer in the range of `[0,1,2,3]` which are increments in 90°."""
+KCellSpec: TypeAlias = (
+    "int | str | KCellSpecDict | ProtoTKCell[Any] | Callable[..., ProtoTKCell[Any]]"
+)

tests/test_layout.py

@@ -270,5 +270,65 @@ def test_kclayout_assign(kcl: kf.KCLayout, layers: Layers) -> None:
     assert len(list(kcl2.layout.each_cell())) == 1
 
 
+def test_get_component(layers: Layers) -> None:
+    # normal functions
+    kf.kcl.get_component(
+        "straight", width=1000, length=10_000, layer=kf.kdb.LayerInfo(1, 0)
+    )
+    kf.kcl.get_component(
+        kf.cells.straight.straight, width=1, length=10, layer=layers.WG
+    )
+    kf.kcl.get_component(
+        kf.cells.straight.straight(width=1, length=10, layer=layers.WG)
+    )
+    kf.kcl.get_component(
+        kf.cells.straight.straight(width=1, length=10, layer=layers.WG).cell_index()
+    )
+
+    # output_type functions
+    kf.kcl.get_component(
+        "straight",
+        width=1000,
+        length=10_000,
+        layer=kf.kdb.LayerInfo(1, 0),
+        output_type=kf.DKCell,
+    )
+    kf.kcl.get_component(
+        kf.cells.straight.straight,
+        width=1,
+        length=10,
+        layer=layers.WG,
+        output_type=kf.DKCell,
+    )
+    kf.kcl.get_component(
+        kf.cells.straight.straight(width=1, length=10, layer=layers.WG),
+        output_type=kf.DKCell,
+    )
+    kf.kcl.get_component(
+        kf.cells.straight.straight(width=1, length=10, layer=layers.WG).cell_index(),
+        output_type=kf.DKCell,
+    )
+
+    # raises errors
+    with pytest.raises(ValueError):
+        kf.kcl.get_component(
+            kf.cells.straight.straight(width=1, length=10, layer=layers.WG),
+            output_type=kf.DKCell,
+            width=1,
+            length=10,
+            layer=layers.WG,
+        )
+    with pytest.raises(ValueError):
+        kf.kcl.get_component(
+            kf.cells.straight.straight(
+                width=1, length=10, layer=layers.WG
+            ).cell_index(),
+            output_type=kf.DKCell,
+            width=1,
+            length=10,
+            layer=layers.WG,
+        )
+
+
 if __name__ == "__main__":
     pytest.main(["-s", __file__])