Don't use runtime_checkable

It only checks for the existence of properties and is a bit misleading

Author: delfick

strcs/__init__.py

@@ -6,6 +6,8 @@
     FromMeta,
     MergedMetaAnnotation,
     MetaAnnotation,
+    is_adjustable_creator,
+    is_adjustable_meta,
 )
 from .args_extractor import ArgsExtractor
 from .decorator import (
@@ -49,5 +51,7 @@
     "TypeCache",
     "WrappedCreator",
     "errors",
+    "is_adjustable_creator",
+    "is_adjustable_meta",
     "resolve_types",
 ]

strcs/annotations.py

@@ -19,7 +19,7 @@
 object as a creator override.
 """
 
-from typing import TYPE_CHECKING, Generic, Protocol, TypeVar, runtime_checkable
+from typing import TYPE_CHECKING, Generic, Protocol, TypeGuard, TypeVar
 
 import attrs
 
@@ -38,7 +38,6 @@
 T = TypeVar("T")
 
 
-@runtime_checkable
 class AdjustableMeta(Protocol[T]):
     """
     An interface used to modify the meta object when creating a field.
@@ -55,7 +54,10 @@ class AdjustableMeta(Protocol[T]):
     def adjusted_meta(self, meta: Meta, typ: Type[T], type_cache: TypeCache) -> Meta: ...
 
 
-@runtime_checkable
+def is_adjustable_meta(meta: object) -> TypeGuard[AdjustableMeta]:
+    return hasattr(meta, "adjusted_meta")
+
+
 class AdjustableCreator(Protocol[T]):
     """
     An interface used to modify the creator used when creating a field.
@@ -88,6 +90,10 @@ def adjusted_creator(
     ) -> ConvertFunction[T] | None: ...
 
 
+def is_adjustable_creator(meta: object) -> TypeGuard[AdjustableCreator]:
+    return hasattr(meta, "adjusted_creator")
+
+
 @attrs.define
 class MetaAnnotation:
     """
@@ -226,7 +232,7 @@ def adjusted_meta(self, meta: Meta, typ: Type[T], type_cache: TypeCache) -> Meta
         if self.meta is None:
             return meta
 
-        if isinstance(self.meta, AdjustableMeta):
+        if is_adjustable_meta(self.meta):
             return self.meta.adjusted_meta(meta, typ, type_cache)
 
         if attrs.has(self.meta.__class__):

strcs/disassemble/_base.py

@@ -653,11 +653,13 @@ def ann(self) -> Union["AdjustableMeta[T]", "AdjustableCreator[T]"] | None:
             # TODO: support multiple annotations
             annotation = self.annotations[0]
 
-            if isinstance(annotation, AdjustableMeta):
+            from ..annotations import is_adjustable_creator, is_adjustable_meta
+
+            if is_adjustable_meta(annotation):
                 ann = annotation
             elif isinstance(annotation, MetaAnnotation | MergedMetaAnnotation):
                 ann = Ann[T](annotation)
-            elif isinstance(annotation, AdjustableCreator):
+            elif is_adjustable_creator(annotation):
                 ann = annotation
             elif callable(annotation):
                 ann = Ann[T](creator=annotation)

strcs/hints.py

@@ -23,7 +23,6 @@
     TypeGuard,
     TypeVar,
     Union,
-    runtime_checkable,
 )
 
 import attrs
@@ -41,7 +40,6 @@ class IsField(Protocol):
     name: str
 
 
-@runtime_checkable
 class WithResolvedTypes(Protocol[C]):
     """
     Strcs will mark classes it has resolved types for to prevent recursive loops.

strcs/hooks.py

@@ -11,7 +11,10 @@
 
 import cattrs
 
-from .annotations import AdjustableCreator, AdjustableMeta
+from .annotations import (
+    is_adjustable_creator,
+    is_adjustable_meta,
+)
 from .decorator import ConvertDefinition, ConvertFunction, CreateArgs
 from .disassemble import Type, TypeCache, fill, instantiate
 from .meta import Meta
@@ -151,10 +154,10 @@ def convert(self, value: object, typ: type[T] | Type[T]) -> T:
         if normal_creator and creator is None:
             creator = normal_creator
 
-        if isinstance(want.ann, AdjustableMeta | AdjustableCreator):
-            if isinstance(want.ann, AdjustableMeta):
+        if is_adjustable_meta(want.ann) or is_adjustable_creator(want.ann):
+            if is_adjustable_meta(want.ann):
                 meta = want.ann.adjusted_meta(meta, want, self.type_cache)
-            if isinstance(want.ann, AdjustableCreator):
+            if is_adjustable_creator(want.ann):
                 creator = want.ann.adjusted_creator(  # type: ignore[assignment]
                     creator,  # type: ignore[arg-type]
                     self.register,

tests/disassemble/test_base.py

@@ -1418,7 +1418,7 @@ def adjusted_meta(
         adjustment = AdjustMeta()
         ann = Dis(Annotated[int, adjustment]).ann
         assert ann is adjustment
-        assert isinstance(ann, strcs.AdjustableMeta)
+        assert strcs.is_adjustable_meta(ann)
 
         meta = strcs.Meta({"two": 2})
         m = ann.adjusted_meta(meta, Dis(int), type_cache)