evgenyshulman commented on a change in pull request #8962:
URL: https://github.com/apache/airflow/pull/8962#discussion_r429893722



##########
File path: airflow/operators/python.py
##########
@@ -145,6 +148,144 @@ def execute_callable(self):
         return self.python_callable(*self.op_args, **self.op_kwargs)
 
 
+class _PythonFunctionalOperator(BaseOperator):
+    """
+    Wraps a Python callable and captures args/kwargs when called for execution.
+
+    :param python_callable: A reference to an object that is callable
+    :type python_callable: python callable
+    :param multiple_outputs: if set, function return value will be
+        unrolled to multiple XCom values. Dict will unroll to xcom values with 
keys as keys.
+        Defaults to False.
+    :type multiple_outputs: bool
+    """
+
+    template_fields = ('_op_args', '_op_kwargs')
+    ui_color = '#ffefeb'
+
+    # since we won't mutate the arguments, we should just do the shallow copy
+    # there are some cases we can't deepcopy the objects(e.g protobuf).
+    shallow_copy_attrs = ('python_callable',)
+
+    @apply_defaults
+    def __init__(
+        self,
+        python_callable: Callable,
+        multiple_outputs: bool = False,
+        *args,
+        **kwargs
+    ) -> None:
+        self._validate_python_callable(python_callable)
+        super().__init__(*args, **kwargs)
+        self.python_callable = python_callable
+        self.multiple_outputs = multiple_outputs
+        self._kwargs = kwargs
+        self._op_args: List[Any] = []
+        self._called = False
+        self._op_kwargs: Dict[str, Any] = {}
+
+    @staticmethod
+    def _get_unique_task_id(task_id: str, dag: Optional[DAG]) -> str:
+        dag = dag or DagContext.get_current_dag()
+        if not dag or task_id not in dag.task_ids:
+            return task_id
+        core = re.split(r'__\d+$', task_id)[0]
+        suffixes = sorted(
+            [int(re.split(r'^.+__', task_id)[1])
+             for task_id in dag.task_ids
+             if re.match(rf'^{core}__\d+$', task_id)]
+        )
+        if not suffixes:
+            return f'{core}__1'
+        return f'{core}__{suffixes[-1] + 1}'
+
+    @staticmethod
+    def _validate_python_callable(python_callable):
+        if not callable(python_callable):
+            raise TypeError('`python_callable` param must be callable')
+        if 'self' in signature(python_callable).parameters.keys():
+            raise AirflowException('@task does not support methods')
+
+    def __call__(self, *args, **kwargs):
+        # If args/kwargs are set, then operator has been called. Raise 
exception
+        if self._called:
+            raise AirflowException('@task decorated functions can only be 
called once. If you need to reuse '
+                                   'it several times in a DAG, use the `copy` 
method.')
+
+        # If we have no DAG, reinitialize class to capture DAGContext and DAG 
default args.
+        if not self.has_dag():
+            self.__init__(python_callable=self.python_callable,
+                          multiple_outputs=self.multiple_outputs,
+                          **self._kwargs)
+
+        # Capture args/kwargs
+        self._op_args = args
+        self._op_kwargs = kwargs
+        self._called = True
+        return XComArg(self)
+
+    def copy(self, task_id: Optional[str] = None, **kwargs):
+        """
+        Create a copy of the task, allow to overwrite ctor kwargs if needed.
+
+        If alias is created a new DAGContext, apply defaults and set new DAG 
as the operator DAG.
+
+        :param task_id: Task id for the new operator
+        :type task_id: Optional[str]
+        """
+        _old_kwargs = self._kwargs
+        if task_id:
+            _old_kwargs['task_id'] = task_id

Review comment:
       [minor] there is a side affect on self._kwargs, it doesn't break 
anything now but can lead to problems in the future.




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