4456 optional import issue on top-level modules -- monai.handlers/monai.engines

monai/engines/utils.py

@@ -22,7 +22,9 @@
 if TYPE_CHECKING:
     from ignite.engine import EventEnum
 else:
-    EventEnum, _ = optional_import("ignite.engine", IgniteInfo.OPT_IMPORT_VERSION, min_version, "EventEnum")
+    EventEnum, _ = optional_import(
+        "ignite.engine", IgniteInfo.OPT_IMPORT_VERSION, min_version, "EventEnum", as_type="base"
+    )
 
 __all__ = [
     "IterationEvents",

monai/engines/workflow.py

@@ -24,7 +24,7 @@
 
 from .utils import engine_apply_transform
 
-IgniteEngine, _ = optional_import("ignite.engine", IgniteInfo.OPT_IMPORT_VERSION, min_version, "Engine")
+IgniteEngine, _ = optional_import("ignite.engine", IgniteInfo.OPT_IMPORT_VERSION, min_version, "Engine", as_type="")
 State, _ = optional_import("ignite.engine", IgniteInfo.OPT_IMPORT_VERSION, min_version, "State")
 Events, _ = optional_import("ignite.engine", IgniteInfo.OPT_IMPORT_VERSION, min_version, "Events")
 

monai/handlers/ignite_metric.py

@@ -19,9 +19,9 @@
 from monai.utils import min_version, optional_import
 
 idist, _ = optional_import("ignite", IgniteInfo.OPT_IMPORT_VERSION, min_version, "distributed")
-Metric, _ = optional_import("ignite.metrics", IgniteInfo.OPT_IMPORT_VERSION, min_version, "Metric")
+Metric, _ = optional_import("ignite.metrics", IgniteInfo.OPT_IMPORT_VERSION, min_version, "Metric", as_type="base")
 reinit__is_reduced, _ = optional_import(
-    "ignite.metrics.metric", IgniteInfo.OPT_IMPORT_VERSION, min_version, "reinit__is_reduced"
+    "ignite.metrics.metric", IgniteInfo.OPT_IMPORT_VERSION, min_version, "reinit__is_reduced", as_type="decorator"
 )
 if TYPE_CHECKING:
     from ignite.engine import Engine

monai/handlers/parameter_scheduler.py

@@ -45,10 +45,10 @@ def __init__(
         vc_kwargs: Dict,
         epoch_level: bool = False,
         name: Optional[str] = None,
-        event=Events.ITERATION_COMPLETED,
+        event=None,
     ):
         self.epoch_level = epoch_level
-        self.event = event
+        self.event = event if event is not None else Events.ITERATION_COMPLETED
 
         self._calculators = {
             "linear": self._linear,

monai/utils/module.py

@@ -309,6 +309,7 @@ def optional_import(
     descriptor: str = OPTIONAL_IMPORT_MSG_FMT,
     version_args=None,
     allow_namespace_pkg: bool = False,
+    as_type: str = "default",
 ) -> Tuple[Any, bool]:
     """
     Imports an optional module specified by `module` string.
@@ -323,6 +324,10 @@ def optional_import(
         descriptor: a format string for the final error message when using a not imported module.
         version_args: additional parameters to the version checker.
         allow_namespace_pkg: whether importing a namespace package is allowed. Defaults to False.
+        as_type: there are cases where the optionally imported object is used as
+            a base class, or a decorator, the exceptions should raise accordingly. The current supported values
+            are "default" (call once to raise), "decorator" (call the constructor and the second call to raise),
+            and anything else will return a lazy class that can be used as a base class (call the constructor to raise).
 
     Returns:
         The imported module and a boolean flag indicating whether the import is successful.
@@ -409,7 +414,22 @@ def __call__(self, *_args, **_kwargs):
             """
             raise self._exception
 
-    return _LazyRaise(), False
+        def __getitem__(self, item):
+            raise self._exception
+
+        def __iter__(self):
+            raise self._exception
+
+    if as_type == "default":
+        return _LazyRaise(), False
+
+    class _LazyCls(_LazyRaise):
+        def __init__(self, *_args, **kwargs):
+            super().__init__()
+            if not as_type.startswith("decorator"):
+                raise self._exception
+
+    return _LazyCls, False
 
 
 def require_pkg(

tests/min_tests.py

@@ -207,10 +207,7 @@ def run_testsuit():
     from monai.utils.module import load_submodules
 
     _, err_mod = load_submodules(sys.modules["monai"], True)
-    if err_mod:
-        print(err_mod)
-        # expecting that only engines and handlers are not imported
-        assert sorted(err_mod) == ["monai.engines", "monai.handlers"]
+    assert not err_mod
 
     # testing all modules
     test_runner = unittest.TextTestRunner(stream=sys.stdout, verbosity=2)