Make module level import report warning

src/spox/_future.py

@@ -165,7 +165,7 @@ def not_(self, a: Var) -> Var:
 
 
 @contextmanager
-def operator_overloading(
+def _operator_overloading(
     op, type_promotion: bool = False, constant_promotion: bool = True
 ):
     """Enable operator overloading on Var for this block.
@@ -202,10 +202,6 @@ def operator_overloading(
     ...    return x * y
     >>> assert foo()._get_value() == np.array(6)
     """
-    warnings.warn(
-        "using operator_overloading is deprecated, consider using https://github.com/Quantco/ndonnx instead",
-        DeprecationWarning,
-    )
     prev_dispatcher = Var._operator_dispatcher
     Var._operator_dispatcher = _NumpyLikeOperatorDispatcher(
         op, type_promotion, constant_promotion
@@ -214,6 +210,17 @@ def operator_overloading(
     Var._operator_dispatcher = prev_dispatcher
 
 
+def __getattr__(name):
+    if name == "operator_overloading":
+        warnings.warn(
+            "using 'operator_overloading' is deprecated, consider using https://github.com/Quantco/ndonnx instead",
+            DeprecationWarning,
+        )
+        return _operator_overloading
+
+    raise AttributeError(f"module {__name__} has no attribute {name}")
+
+
 __all__ = [
     # Type warning levels
     "TypeWarningLevel",
@@ -226,5 +233,6 @@ def operator_overloading(
     "set_value_prop_backend",
     "value_prop_backend",
     # Operator overloading on Var
-    "operator_overloading",
+    "operator_overloading",  # noqa: F822
+    "__getattr__",
 ]