For visibility of folks There s a separate issue we ve notic

Question

For visibility of folks There s a separate issue we ve noticed with `NamedTuple` vs `dataclass` support ` workflow` and ` dynamic` seem to have some special Promise handling for `NamedTuple` types specifically Within a ` workflow` I can construct `NamedTuple` instances including passing promise objects into their attributes Within a ` workflow` I can access attributes on a `NamedTuple` instance and get a promise object back which resolves to a field in that record The return types of these seem equivalent to the original `NamedTuple` definition but not the same as ie `isinstance output MyNamedTuple == False` on a task output from a task that returns a `MyNamedTuple` even though the object in all other respects pretends to be a `MyNamedTuple` instance None of this behavior is supported for `dataclass` types Including the wonky `isinstance` stuff Is this special cased logic for `NamedTuple` We d really love to use exactly one of `NamedTuple` or `dataclass` for all of our structures in our Flyte workflows The above behaviors are very desirable in fact I think I asked for exactly this ~6mo ago very excited to see it But the mis matched support of features for `NamedTuple` and `dataclass` is making it hard for us to put a stake in the ground and just pick one Can we either implement the above behaviors minus the isinstance bit for `dataclass` or allow `NamedTuple` s as task inputs Let me explain what NamedTuple are meant to be So when you have multi valued return from a python function i e ```def foo gt int int int return 10 10 10``` In this case the `int int int` is actually a tuple in the python world right as you can receive it as ```x = foo ``` and `x` would be a tuple But Python does special handing for Tuples as the following is valid ```m n o = foo ``` Flyte actually supports multiple values as outputs These are not python but arbitrary lanugages By default flytekit names all the return types as `o1 o2 on` This is because every returned value in Flyte is actually bound by its name `o1` etc in the downstream consumer Flyte also supports naming the outputs as `x y z` instead of the `o1 ` But in python there is no easy way to name the outputs So we decided to use NamedTuples Rationale NamedTuples behave the same as Tuples but allow naming NamedTuples are not handled specially in flytekit except for the naming On the otherhand dataclasses are very python native thing We wanted users to be able to return arbitrarily complex objects as a single value so in the above example ```def foo gt int dataclass ``` Dataclasses are sent through flyte as opaque Json Objects And the engine tries to not load them to keep its security high thus dataclasses are more like `int` `tuples and namedtuples` cannot be returned today as an invidual object ```def foo gt int tuple ``` Is not valid