Add DataclassInstance for runtime type_checking

src/huggingface_hub/hub_mixin.py

@@ -1,9 +1,9 @@
 import inspect
 import json
 import os
-from dataclasses import asdict, dataclass, is_dataclass
+from dataclasses import Field, asdict, dataclass, is_dataclass
 from pathlib import Path
-from typing import TYPE_CHECKING, Any, Callable, Dict, List, Optional, Tuple, Type, TypeVar, Union
+from typing import TYPE_CHECKING, Any, Callable, ClassVar, Dict, List, Optional, Protocol, Tuple, Type, TypeVar, Union
 
 import packaging.version
 
@@ -25,7 +25,15 @@
 
 
 if TYPE_CHECKING:
-    from _typeshed import DataclassInstance
+    from _typeshed import DataclassInstance  # type: ignore
+else:
+
+    class DataclassInstance(Protocol):  # type: ignore
+        __dataclass_fields__: ClassVar[Dict[str, Field]]
+
+
+Dataclass = TypeVar("Dataclass", bound=DataclassInstance)
+DataclassType = Type[Dataclass]
 
 if is_torch_available():
     import torch  # type: ignore
@@ -175,7 +183,7 @@ class ModelHubMixin:
     ```
     """
 
-    _hub_mixin_config: Optional[Union[dict, "DataclassInstance"]] = None
+    _hub_mixin_config: Optional[Union[dict, DataclassType]] = None
     # ^ optional config attribute automatically set in `from_pretrained`
     _hub_mixin_info: MixinInfo
     # ^ information about the library integrating ModelHubMixin (used to generate model card)
@@ -366,7 +374,7 @@ def save_pretrained(
         self,
         save_directory: Union[str, Path],
         *,
-        config: Optional[Union[dict, "DataclassInstance"]] = None,
+        config: Optional[Union[dict, DataclassType]] = None,
         repo_id: Optional[str] = None,
         push_to_hub: bool = False,
         model_card_kwargs: Optional[Dict[str, Any]] = None,
@@ -618,7 +626,7 @@ def push_to_hub(
         self,
         repo_id: str,
         *,
-        config: Optional[Union[dict, "DataclassInstance"]] = None,
+        config: Optional[Union[dict, DataclassType]] = None,
         commit_message: str = "Push model using huggingface_hub.",
         private: Optional[bool] = None,
         token: Optional[str] = None,
@@ -825,7 +833,7 @@ def _load_as_safetensor(cls, model: T, model_file: str, map_location: str, stric
         return model
 
 
-def _load_dataclass(datacls: Type["DataclassInstance"], data: dict) -> "DataclassInstance":
+def _load_dataclass(datacls: DataclassType, data: dict) -> DataclassType:
     """Load a dataclass instance from a dictionary.
 
     Fields not expected by the dataclass are ignored.