Expose `get_weight` to Torch Hub (#6026)

* Prefixing `_get_enum_from_fn` with underscore

* Exposing `get_weight` to Torch Hub

hubconf.py

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

torchvision/models/_api.py

@@ -107,7 +107,7 @@ def get_weight(name: str) -> WeightsEnum:
     return weights_enum.from_str(value_name)
 
 
-def get_enum_from_fn(fn: Callable) -> WeightsEnum:
+def _get_enum_from_fn(fn: Callable) -> WeightsEnum:
     """
     Internal method that gets the weight enum of a specific model builder method.
     Might be removed after the handle_legacy_interface is removed.

torchvision/models/detection/backbone_utils.py

@@ -6,7 +6,7 @@ from torchvision.ops import misc as misc_nn_ops
 from torchvision.ops.feature_pyramid_network import ExtraFPNBlock, FeaturePyramidNetwork, LastLevelMaxPool
 
 from .. import mobilenet, resnet
-from .._api import WeightsEnum, get_enum_from_fn
+from .._api import WeightsEnum, _get_enum_from_fn
 from .._utils import IntermediateLayerGetter, handle_legacy_interface
 
 
@@ -62,7 +62,7 @@ class BackboneWithFPN(nn.Module):
 @handle_legacy_interface(
     weights=(
         "pretrained",
-        lambda kwargs: get_enum_from_fn(resnet.__dict__[kwargs["backbone_name"]]).from_str("IMAGENET1K_V1"),
+        lambda kwargs: _get_enum_from_fn(resnet.__dict__[kwargs["backbone_name"]]).from_str("IMAGENET1K_V1"),
     ),
 )
 def resnet_fpn_backbone(
@@ -177,7 +177,7 @@ def _validate_trainable_layers(
 @handle_legacy_interface(
     weights=(
         "pretrained",
-        lambda kwargs: get_enum_from_fn(mobilenet.__dict__[kwargs["backbone_name"]]).from_str("IMAGENET1K_V1"),
+        lambda kwargs: _get_enum_from_fn(mobilenet.__dict__[kwargs["backbone_name"]]).from_str("IMAGENET1K_V1"),
     ),
 )
 def mobilenet_backbone(