Expose on Hub the public methods of the registration API (#6364)

* Expose on Hub the public methods of the registration API

* Limit methods and update docs.

Author: datumbox

docs/source/models.rst

@@ -176,6 +176,15 @@ Most pre-trained models can be accessed directly via PyTorch Hub without having
     weights = torch.hub.load("pytorch/vision", "get_weight", weights="ResNet50_Weights.IMAGENET1K_V2")
     model = torch.hub.load("pytorch/vision", "resnet50", weights=weights)
 
+You can also retrieve all the available weights of a specific model via PyTorch Hub by doing:
+
+.. code:: python
+
+    import torch
+
+    weight_enum = torch.hub.load("pytorch/vision", "get_model_weights", name="resnet50")
+    print([weight for weight in weight_enum])
+
 The only exception to the above are the detection models included on
 :mod:`torchvision.models.detection`. These models require TorchVision
 to be installed because they depend on custom C++ operators.

hubconf.py

@@ -1,7 +1,7 @@
 # Optional list of dependencies required by the package
 dependencies = ["torch"]
 
-from torchvision.models import get_weight
+from torchvision.models import get_model_weights, get_weight
 from torchvision.models.alexnet import alexnet
 from torchvision.models.convnext import convnext_base, convnext_large, convnext_small, convnext_tiny
 from torchvision.models.densenet import densenet121, densenet161, densenet169, densenet201

torchvision/models/_api.py

@@ -115,7 +115,7 @@ def get_weight(name: str) -> WeightsEnum:
 W = TypeVar("W", bound=WeightsEnum)
 
 
-def get_model_weights(model: Union[Callable, str]) -> W:
+def get_model_weights(name: Union[Callable, str]) -> W:
     """
     Retuns the weights enum class associated to the given model.
 
@@ -127,8 +127,7 @@ def get_model_weights(model: Union[Callable, str]) -> W:
     Returns:
         weights_enum (W): The weights enum class associated with the model.
     """
-    if isinstance(model, str):
-        model = find_model(model)
+    model = find_model(name) if isinstance(name, str) else name
     return cast(W, _get_enum_from_fn(model))