avoid lambda functions

gdsfactory/components/crossing_waveguide.py

@@ -119,8 +119,11 @@ def crossing(
     return c
 
 
+_taper = partial(taper, width2=2.5, length=3)
+
+
 @cell
-def crossing_from_taper(taper=lambda: taper(width2=2.5, length=3.0)) -> Component:
+def crossing_from_taper(taper=_taper) -> Component:
     """Returns Crossing based on a taper.
 
     The default is a dummy taper.

gdsfactory/components/taper_adiabatic.py

@@ -30,12 +30,24 @@
 )
 
 
+def neff_TE1550SOI_220nm(w: float) -> float:
+    """Returns the effective index of the fundamental TE mode for a 220nm-thick core with 3.45 index, fully clad with 1.44 index.
+
+    Args:
+        w: width in um.
+
+    Returns:
+        effective index
+    """
+    return np.poly1d(adiabatic_polyfit_TE1550SOI_220nm)(w)
+
+
 @gf.cell
 def taper_adiabatic(
     width1: float = 0.5,
     width2: float = 5.0,
     length: float = 0,
-    neff_w: Callable = lambda w: np.poly1d(adiabatic_polyfit_TE1550SOI_220nm)(w),
+    neff_w: Callable = neff_TE1550SOI_220nm,
     alpha: float = 1,
     wavelength: float = 1.55,
     npoints: int = 200,

gdsfactory/serialization.py

@@ -6,6 +6,7 @@
 import inspect
 import pathlib
 from collections.abc import KeysView as dict_keys
+from types import FunctionType
 from typing import Any
 
 import gdstk
@@ -71,6 +72,16 @@ def clean_value_json(
         value = np.round(value, DEFAULT_SERIALIZATION_MAX_DIGITS)
         return orjson.loads(orjson.dumps(value, option=orjson.OPT_SERIALIZE_NUMPY))
 
+    # Add a condition to handle lambda functions specifically
+    elif (
+        callable(value)
+        and isinstance(value, FunctionType)
+        and value.__name__ == "<lambda>"
+    ):
+        raise ValueError(
+            "Unable to serialize lambda function. Use a named function instead."
+        )
+
     elif callable(value) and isinstance(value, functools.partial):
         return clean_value_partial(value, include_module=True)
 

test-data-regression/test_settings_crossing_from_taper_.yml

@@ -4,4 +4,8 @@ module: gdsfactory.components.crossing_waveguide
 name: crossing_from_taper
 settings:
   taper:
-    function: <lambda>
+    function: taper
+    module: gdsfactory.components.taper
+    settings:
+      length: 3
+      width2: 2.5

test-data-regression/test_settings_taper_adiabatic_.yml

@@ -7,7 +7,7 @@ settings:
   cross_section: xs_sc
   length: 0
   neff_w:
-    function: <lambda>
+    function: neff_TE1550SOI_220nm
   npoints: 200
   wavelength: 1.55
   width1: 0.5