[GitHub] [airflow] josh-fell commented on a diff in pull request #29445: Better handle forward type definitions in `@task.python` for multiple output

["josh-fell (via GitHub)" <gi...@apache.org>]

josh-fell commented on code in PR #29445:
URL: https://github.com/apache/airflow/pull/29445#discussion_r1102809860


##########
airflow/decorators/base.py:
##########
@@ -296,7 +297,20 @@ class _TaskDecorator(ExpandableFactory, Generic[FParams, FReturn, OperatorSubcla
     @multiple_outputs.default
     def _infer_multiple_outputs(self):
         try:
-            return_type = typing_extensions.get_type_hints(self.function).get("return", Any)
+            # We only care about the return annotation, not anything about the parameters
+            def fake():
+                ...
+
+            fake.__annotations__ = {"return": self.function.__annotations__["return"]}
+
+            return_type = typing_extensions.get_type_hints(fake, self.function.__globals__).get("return", Any)
+        except NameError as e:
+            warnings.warn(
+                "Cannot infer multiple_outputs with forward type references that are not imported. "

Review Comment:
   The warning is nice. I think it would be helpful for the message to include the function name too. WDYT?
   
   Something like:
   ```suggestion
                   f"Cannot infer multiple_outputs for TaskFlow function {self.function.__name__!r} with forward type references that are not imported. "
   ```



##########
airflow/decorators/base.py:
##########
@@ -296,7 +297,20 @@ class _TaskDecorator(ExpandableFactory, Generic[FParams, FReturn, OperatorSubcla
     @multiple_outputs.default
     def _infer_multiple_outputs(self):
         try:
-            return_type = typing_extensions.get_type_hints(self.function).get("return", Any)
+            # We only care about the return annotation, not anything about the parameters
+            def fake():
+                ...
+
+            fake.__annotations__ = {"return": self.function.__annotations__["return"]}

Review Comment:
   ```suggestion
               fake.__annotations__ = {"return": self.function.__annotations__.get("return")}
   ```
   Just in case there isn't a return annotation.



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