Dont use mutable default value for class variable

zenml-io · Nov 27, 2021 · 4ed49d4 · 4ed49d4
1 parent 84e2fe1
commit 4ed49d4
Showing 1 changed file with 4 additions and 2 deletions.
diff --git a/src/zenml/steps/utils.py b/src/zenml/steps/utils.py
@@ -222,7 +222,9 @@ class _FunctionExecutor(BaseExecutor):
     """Base TFX Executor class which is compatible with ZenML steps"""
 
     _FUNCTION = staticmethod(lambda: None)
-    materializers: ClassVar[Dict[str, Type["BaseMaterializer"]]] = {}
+    materializers: ClassVar[
+        Optional[Dict[str, Type["BaseMaterializer"]]]
+    ] = None
 
     def resolve_materializer_with_registry(
         self, param_name: str, artifact: BaseArtifact
@@ -348,7 +350,7 @@ def Do(
                 output_artifacts = {k: v[0] for k, v in output_dict.items()}
                 context = StepContext(
                     step_name=getattr(self, PARAM_STEP_NAME),
-                    output_materializers=self.materializers,
+                    output_materializers=self.materializers or {},
                     output_artifacts=output_artifacts,
                 )
                 function_params[arg] = context