Why does `action {}` return `ActionFlow` instead o...

# uniflow

[Erik]

Why does action {} return ActionFlow instead of Unit, is there a use case to have that object somewhere outside of the Uniflow internals?

[arnaud.giuliani]

it is a form of contract, an action function should return an ActionFlow to be valid. There is a validator for testing your ViewModel in the uniflow-test module

[arnaud.giuliani]

if you have better suggestion 👍

[Erik]

Where is it a contract?
In practical use of a DataFlow if a write a function as fun getWeather() = action { /*..*/ } then my data flow exposes the returned ActionFlow object to the caller. Why is that necessary? The public API of the ActionFlow class has all kinds of properties and functions that should likely never be called or callable from outside of a DataFlow. Do you have an example of where having all this access is useful?

[Erik]

An example if a user pressing a button to submit a form. I expect my DataFlow to just expose a function fun submit(): Unit. Of course I could write

fun submit() {
    action { /*..*/ }
}

But then I actively must ignore the returned value from action { /*..*/ }. What is its intended use?
Furthermore, wouldn't it be nicer to be able to write

fun submit() = action { /*..*/ }

while Unit is returned, indicating that the submit function is fire and forget: it returns quickly but ensures that an action is submitted to its internals that might (or might not) lead to events and state changes.

[Erik]

Let me take a look at uniflow-test now

[Erik]

I've seen the validator now and I understand what it validates, but I still don't understand why all public DataFlow functions must return an ActionFlow.

[arnaud.giuliani]

I’ve seen the validator now and I understand what it validates, but I still don’t understand why all public DataFlow functions must return an ActionFlow.

Yes, I see your point

[arnaud.giuliani]

not sure it’s a consistent way to effectively avoid any side effect directly on a ActionFlow, we don’t need to see it 👍

[arnaud.giuliani]

I can help validate VM with a Kotlin compiler instead, it will have more sense