reference object method as _target_

Signed-off-by: Wenqi Li <[email protected]>

monai/bundle/config_item.py

@@ -236,7 +236,7 @@ def resolve_module_name(self):
         config = dict(self.get_config())
         target = config.get("_target_")
         if not isinstance(target, str):
-            raise ValueError("must provide a string for the `_target_` of component to instantiate.")
+            return target
 
         module = self.locator.get_component_module_name(target)
         if module is None:

monai/utils/module.py

@@ -226,8 +226,7 @@ def instantiate(path: str, **kwargs):
             for `partial` function.
 
     """
-
-    component = locate(path)
+    component = locate(path) if isinstance(path, str) else path
     if component is None:
         raise ModuleNotFoundError(f"Cannot locate class or function path: '{path}'.")
     try:

tests/test_config_parser.py

@@ -248,6 +248,14 @@ def test_lambda_reference(self):
         result = trans(np.ones(64))
         self.assertTupleEqual(result.shape, (1, 8, 8))
 
+    def test_non_str_target(self):
+        configs = {
+            "forward": {"_target_": "$@model().forward", "x": "$torch.rand(1, 3, 256, 256)"},
+            "model": {"_target_": "monai.networks.nets.resnet.resnet18", "pretrained": False, "spatial_dims": 2},
+        }
+        breakpoint()
+        self.assertisTrue(callable(ConfigParser(config=configs).forward))
+
     def test_error_instance(self):
         config = {"transform": {"_target_": "Compose", "transforms_wrong_key": []}}
         parser = ConfigParser(config=config)