fixing up/removing todos

api/src/opentrons/protocol_api/_parameters.py

@@ -1,6 +1,6 @@
 from typing import Dict, Optional, Any
 
-from opentrons.protocols.parameters.types import AllowedTypes
+from opentrons.protocols.parameters.types import AllowedTypes, ParameterNameError
 
 
 class Parameters:
@@ -14,14 +14,18 @@ def _getparam(self, variable_name: str) -> Any:
         return getattr(self, f"_{variable_name}")
 
     def _initialize_parameter(self, variable_name: str, value: AllowedTypes) -> None:
-        # TODO raise an error if the variable name already exists to prevent overwriting anything important
         if not hasattr(self, variable_name) and not hasattr(self, f"_{variable_name}"):
             setattr(self, f"_{variable_name}", value)
             prop = property(
                 fget=lambda s, v=variable_name: Parameters._getparam(s, v)  # type: ignore[misc]
             )
             setattr(Parameters, variable_name, prop)
             self._values[variable_name] = value
+        else:
+            raise ParameterNameError(
+                f"Cannot use {variable_name} as a variable name, either duplicates another"
+                f" parameter name, Opentrons reserved function, or Python built-in"
+            )
 
     def get_all(self) -> Dict[str, AllowedTypes]:
         return self._values

api/src/opentrons/protocols/parameters/types.py

@@ -13,7 +13,6 @@ class ParameterChoices(TypedDict):
     value: AllowedTypes
 
 
-# TODO these should inherit from shared_data exceptions
 class ParameterValueError(ValueError):
     """An error raised when a parameter value is not valid."""
 

api/src/opentrons/protocols/parameters/validation.py

@@ -31,7 +31,7 @@ def ensure_variable_name(variable_name: str) -> str:
             "Variable name must only contain alphanumeric characters, underscores, and cannot start with a digit."
         )
     if keyword.iskeyword(variable_name):
-        raise ParameterNameError("Variable name cannot be a reserved Python key word.")
+        raise ParameterNameError("Variable name cannot be a reserved Python keyword.")
     return variable_name