Would the issue tracker be a good spot to make req...

# compose

[Cody Engel]

Would the issue tracker be a good spot to make requests? I was hoping to do something like this:

@Model
class Name(var name: String = "Android") : ViewModel()

But inheritance isn’t currently supported for Model objects.

We currently use LiveData a lot today but with Compose it seems like unnecessary overhead.

[themishkun]

Imagine how many subtile bugs inheritance would cause when combined with clever stuff @Model tries to do to register observables. Do you really want that? Just use composition over inheritance and smack that @Model as a property of your ViewModel. But before that, try to think: do you even need a ViewModel in the first place?

[Luca Nicoletti]

Imho: no, not anymore 😛

[George Mount]

Many devs have existing systems that they will have to integrate with. In the "What's new" talk, Adam spoke about a future option (he had an effect function) where you'll be able to just observe LiveData objects. It should be just a few lines of code to write a LiveData observer that causes recomposition when the value changes.

[Luca Nicoletti]

https://kotlinlang.slack.com/archives/CJLTWPH7S/p1571895142292400

[Cody Engel]

Why would you not use ViewModel for this? Compose doesn’t save state across configuration changes, ViewModel does.

[Cody Engel]

Model seems to keep track of public properties on a class so allowing for inheritance seems like it would be fine. Asking everyone to annotate with model when that’s the desired default behavior is going to get clumsy and prone to errors

[Chuck Jazdzewski [G]]

Supporting inheritance for @Model classes is in the plan but is not currently supported.

[Luca Nicoletti]

Any particular reason why you’re now blocking it?

[Chuck Jazdzewski [G]]

It requires changes in the @Model lowering transform to support inheritance. The state record needs to inherit from the ancestor state record which is admittedly not that difficult to implement but I have not gotten to it yet.

[Cody Engel]

Yeah talking with everyone today during the sandbox was really helpful. So far there have been work arounds for any wall I’ve hit which is really reassuring and I’m excited to see how this progresses

[themishkun]

@Cody Engel Activity is killed on config changes because current ui toolkit is not reactive. But with compose all you need to do is to change some ambients and trigger recomposition to switch language/theme/configuration. So you can just enable manual handling of config changes and forget about ViewModel

[Cody Engel]

How would you write unit tests for that?

[Cody Engel]

I guess it feels weird to abandon ViewModel, it worked well should still work fine for Compose.

[themishkun]

@Cody Engel Just as you would write unit tests for anything. State update functions can be just functions, you know