Assert that field names are not valid Python attributes

parcels/_core/field.py

@@ -18,6 +18,7 @@
     AllParcelsErrorCodes,
     StatusCode,
 )
+from parcels._core.utils.string import _assert_valid_python_varname
 from parcels._core.utils.time import TimeInterval
 from parcels._core.uxgrid import UxGrid
 from parcels._core.xgrid import XGrid, _transpose_xfield_data_to_tzyx
@@ -103,6 +104,9 @@ def __init__(
             )
         if not isinstance(name, str):
             raise ValueError(f"Expected `name` to be a string, got {type(name)}.")
+        else:
+            _assert_valid_python_varname(name)
+
         if not isinstance(grid, (UxGrid, XGrid)):
             raise ValueError(f"Expected `grid` to be a parcels UxGrid, or parcels XGrid object, got {type(grid)}.")
 
@@ -246,6 +250,11 @@ class VectorField:
     def __init__(
         self, name: str, U: Field, V: Field, W: Field | None = None, vector_interp_method: Callable | None = None
     ):
+        if not isinstance(name, str):
+            raise ValueError(f"Expected `name` to be a string, got {type(name)}.")
+        else:
+            _assert_valid_python_varname(name)
+
         self.name = name
         self.U = U
         self.V = V

parcels/_core/fieldset.py

@@ -11,6 +11,7 @@
 
 from parcels._core.converters import Geographic, GeographicPolar
 from parcels._core.field import Field, VectorField
+from parcels._core.utils.string import _assert_valid_python_varname
 from parcels._core.utils.time import get_datetime_type_calendar
 from parcels._core.utils.time import is_compatible as datetime_is_compatible
 from parcels._core.xgrid import _DEFAULT_XGCM_KWARGS, XGrid
@@ -163,6 +164,11 @@ def add_constant(self, name, value):
         `Diffusion <../examples/tutorial_diffusion.ipynb>`__
         `Periodic boundaries <../examples/tutorial_periodic_boundaries.ipynb>`__
         """
+        if not isinstance(name, str):
+            raise ValueError(f"Expected `name` to be a string, got {type(name)}.")
+        else:
+            _assert_valid_python_varname(name)
+
         if name in self.constants:
             raise ValueError(f"FieldSet already has a constant with name '{name}'")
         if not isinstance(value, (float, np.floating, int, np.integer)):

parcels/_core/particle.py

@@ -2,13 +2,13 @@
 
 import enum
 import operator
-from keyword import iskeyword
 from typing import Literal
 
 import numpy as np
 
 from parcels._compat import _attrgetter_helper
 from parcels._core.statuscodes import StatusCode
+from parcels._core.utils.string import _assert_valid_python_varname
 from parcels._core.utils.time import TimeInterval
 from parcels._reprs import _format_list_items_multiline
 
@@ -46,8 +46,9 @@ def __init__(
         attrs: dict | None = None,
     ):
         if not isinstance(name, str):
-            raise TypeError(f"Variable name must be a string. Got {name=!r}")
-        _assert_valid_python_varname(name)
+            raise ValueError(f"Expected `name` to be a string, got {type(name)}.")
+        else:
+            _assert_valid_python_varname(name)
 
         try:
             dtype = np.dtype(dtype)
@@ -153,12 +154,6 @@ def _assert_no_duplicate_variable_names(*, existing_vars: list[Variable], new_va
             raise ValueError(f"Variable name already exists: {var.name}")
 
 
-def _assert_valid_python_varname(name):
-    if name.isidentifier() and not iskeyword(name):
-        return
-    raise ValueError(f"Particle variable has to be a valid Python variable name. Got {name=!r}")
-
-
 def get_default_particle(spatial_dtype: np.float32 | np.float64) -> ParticleClass:
     if spatial_dtype not in [np.float32, np.float64]:
         raise ValueError(f"spatial_dtype must be np.float32 or np.float64. Got {spatial_dtype=!r}")

parcels/_core/utils/string.py

@@ -0,0 +1,9 @@
+from keyword import iskeyword, kwlist
+
+
+def _assert_valid_python_varname(name):
+    if name.isidentifier() and not iskeyword(name):
+        return
+    raise ValueError(
+        f"Received invalid Python variable name {name!r}. Avoid using the following names: {', '.join(kwlist)}"
+    )