get rid of some users of hasattr()

instead, let's use type checking protocols. Note that this trick
cannot be used for the `hasattr("protocol")` instances of `DiagComm`
because this would lead to cyclic imports.

thanks to [at]kayoub5 for suggesting this!

Signed-off-by: Andreas Lauser <andreas.lauser@mbition.io>
Signed-off-by: Florian Jost <florian.jost@mbition.io>

odxtools/diaglayers/ecuvariant.py

@@ -6,14 +6,14 @@
 
 from typing_extensions import override
 
-from ..diagvariable import DiagVariable
+from ..diagvariable import DiagVariable, HasDiagVariables
 from ..dyndefinedspec import DynDefinedSpec
 from ..ecuvariantpattern import EcuVariantPattern
 from ..exceptions import odxassert
 from ..nameditemlist import NamedItemList
 from ..odxlink import OdxDocFragment, OdxLinkDatabase, OdxLinkRef
 from ..parentref import ParentRef
-from ..variablegroup import VariableGroup
+from ..variablegroup import HasVariableGroups, VariableGroup
 from .diaglayer import DiagLayer
 from .ecuvariantraw import EcuVariantRaw
 from .hierarchyelement import HierarchyElement
@@ -97,10 +97,10 @@ def _compute_available_diag_variables(self,
                                           odxlinks: OdxLinkDatabase) -> Iterable[DiagVariable]:
 
         def get_local_objects_fn(dl: DiagLayer) -> Iterable[DiagVariable]:
-            if not hasattr(dl.diag_layer_raw, "diag_variables"):
+            if not isinstance(dl.diag_layer_raw, HasDiagVariables):
                 return []
 
-            return dl.diag_layer_raw.diag_variables  # type: ignore[no-any-return]
+            return dl.diag_layer_raw.diag_variables
 
         def not_inherited_fn(parent_ref: ParentRef) -> List[str]:
             return parent_ref.not_inherited_variables
@@ -111,10 +111,10 @@ def _compute_available_variable_groups(self,
                                            odxlinks: OdxLinkDatabase) -> Iterable[VariableGroup]:
 
         def get_local_objects_fn(dl: DiagLayer) -> Iterable[VariableGroup]:
-            if not hasattr(dl.diag_layer_raw, "variable_groups"):
+            if not isinstance(dl.diag_layer_raw, HasVariableGroups):
                 return []
 
-            return dl.diag_layer_raw.variable_groups  # type: ignore[no-any-return]
+            return dl.diag_layer_raw.variable_groups
 
         def not_inherited_fn(parent_ref: ParentRef) -> List[str]:
             return []

odxtools/diagvariable.py

@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: MIT
+import typing
 from dataclasses import dataclass
-from typing import Any, Dict, List, Optional
+from typing import Any, Dict, List, Optional, runtime_checkable
 from xml.etree import ElementTree
 
 from .admindata import AdminData
@@ -17,6 +18,14 @@
 from .variablegroup import VariableGroup
 
 
+@runtime_checkable
+class HasDiagVariables(typing.Protocol):
+
+    @property
+    def diag_variables(self) -> "NamedItemList[DiagVariable]":
+        ...
+
+
 @dataclass
 class DiagVariable(IdentifiableElement):
     """Representation of a diagnostic variable

odxtools/nameditemlist.py

@@ -1,15 +1,16 @@
 # SPDX-License-Identifier: MIT
 import abc
+import typing
 from copy import deepcopy
 from keyword import iskeyword
-from typing import (Any, Collection, Dict, Iterable, List, Optional, Protocol, SupportsIndex, Tuple,
-                    TypeVar, Union, cast, overload, runtime_checkable)
+from typing import (Any, Collection, Dict, Iterable, List, Optional, SupportsIndex, Tuple, TypeVar,
+                    Union, cast, overload, runtime_checkable)
 
 from .exceptions import odxraise
 
 
 @runtime_checkable
-class OdxNamed(Protocol):
+class OdxNamed(typing.Protocol):
 
     @property
     def short_name(self) -> str:

odxtools/variablegroup.py

@@ -1,16 +1,26 @@
 # SPDX-License-Identifier: MIT
+import typing
 from dataclasses import dataclass
-from typing import TYPE_CHECKING, List
+from typing import TYPE_CHECKING, List, runtime_checkable
 from xml.etree import ElementTree
 
 from .element import IdentifiableElement, NamedElement
+from .nameditemlist import NamedItemList
 from .odxlink import OdxDocFragment
 from .utils import dataclass_fields_asdict
 
 if TYPE_CHECKING:
     pass
 
 
+@runtime_checkable
+class HasVariableGroups(typing.Protocol):
+
+    @property
+    def variable_groups(self) -> NamedItemList["VariableGroup"]:
+        ...
+
+
 @dataclass
 class VariableGroup(IdentifiableElement):