chore(annotations): cleanup compat and fix ModelSignatureDict type

src/bentoml/_internal/types.py

@@ -11,56 +11,8 @@
 from datetime import time
 from datetime import timedelta
 from types import TracebackType
-from typing import TYPE_CHECKING
-
-if sys.version_info < (3, 8):
-    import collections
-
-    GenericClass = type(t.List)
-
-    BUILTINS_MAPPING = {
-        t.List: list,
-        t.Set: set,
-        t.Dict: dict,
-        t.Tuple: tuple,
-        t.ByteString: bytes,  # https://docs.python.org/3/library/typing.html#typing.ByteString
-        t.Callable: collections.abc.Callable,
-        t.Sequence: collections.abc.Sequence,
-        type(None): None,
-    }
-
-    def _normalize_aliases(type_: t.Type) -> t.Type:
-        if isinstance(type_, t.TypeVar):
-            return type_
-
-        if type_ in BUILTINS_MAPPING:
-            return BUILTINS_MAPPING[type_]
-        return type_
-
-    def get_args(type_: t.Type) -> tuple[t.Type]:
-        if isinstance(type_, GenericClass) and not type_._special:
-            res = type_.__args__
-            if get_origin(type_) is collections.abc.Callable and res[0] is not Ellipsis:
-                res = (list(res[:-1]), res[-1])
-        else:
-            res = ()
-
-        return res
-
-    def get_origin(type_: t.Type) -> t.Type:
-        if isinstance(type_, GenericClass) and not type_._special:
-            ori = type_.__origin__
-        elif hasattr(type_, "_special") and type_._special:
-            ori = type_
-        elif type_ is t.Generic:
-            ori = t.Generic
-        else:
-            ori = None
-        return ori
-
-else:
-    from typing import get_args
-    from typing import get_origin
+from typing import get_args
+from typing import get_origin
 
 __all__ = [
     "MetadataType",
@@ -81,11 +33,6 @@ def get_origin(type_: t.Type) -> t.Type:
 
 JSON_CHARSET = "utf-8"
 
-if TYPE_CHECKING:
-    PathType: t.TypeAlias = str | os.PathLike[str]
-else:
-    PathType = t.Union[str, os.PathLike]
-
 MetadataType: t.TypeAlias = t.Union[
     str,
     bytes,
@@ -102,8 +49,16 @@ def get_origin(type_: t.Type) -> t.Type:
     t.Dict[str, "MetadataType"],
 ]
 
-if TYPE_CHECKING:
-    MetadataDict = t.Dict[str, MetadataType]
+
+class ModelSignatureDict(t.TypedDict, total=False):
+    batchable: bool
+    batch_dim: t.Union[t.Tuple[int, int], int]
+    input_spec: t.Optional[t.Union[t.Tuple[AnyType], AnyType]]
+    output_spec: t.Optional[AnyType]
+
+
+if t.TYPE_CHECKING:
+    PathType: t.TypeAlias = str | os.PathLike[str]
     JSONSerializable: t.TypeAlias = (
         str
         | int
@@ -113,19 +68,12 @@ def get_origin(type_: t.Type) -> t.Type:
         | list["JSONSerializable"]
         | dict[str, "JSONSerializable"]
     )
-
-    class ModelSignatureDict(t.TypedDict, total=False):
-        batchable: bool
-        batch_dim: tuple[int, int] | int | None
-        input_spec: tuple[AnyType] | AnyType | None
-        output_spec: AnyType | None
-
+    MetadataDict = t.Dict[str, MetadataType]
 else:
+    PathType = t.Union[str, os.PathLike]
+    JSONSerializable = t.NewType("JSONSerializable", object)
     # NOTE: remove this when registering hook for MetadataType
     MetadataDict = dict
-    ModelSignatureDict = dict
-
-    JSONSerializable = t.NewType("JSONSerializable", object)
 
 LifecycleHook = t.Callable[[], t.Union[None, t.Coroutine[t.Any, t.Any, None]]]
 
@@ -262,7 +210,7 @@ def issubclass(self, klass: type) -> bool:
             return False
 
 
-if TYPE_CHECKING:
+if t.TYPE_CHECKING:
     from types import UnionType
 
     AnyType: t.TypeAlias = t.Type[t.Any] | UnionType | LazyType[t.Any]