[AssistedInject] Support Generic Factory

Right now we use a Factory and provider to inject generic factories:

I.e:

class ViewModelFactory<VM : ViewModel>
@Inject constructor(private val provider: Provider<VM>) : ViewModelProvider.Factory {
    @Suppress("UNCHECKED_CAST")
    override fun <T : ViewModel> create(modelClass: Class<T>): T = provider.get() as T
}

@Inject lateinit var factory: ViewModelFactory<MyViewModel>

This works great in many places, I was trying to do the same with the assisted factory to achieve something similar, but the AssistedFactory requires a 1-1 mapping from what I can tell and will return an error if there is no matching @AssistedInject

@AssistedFactory
interface StateViewModelFactory<VM : ViewModel> {
    fun create(handle: SavedStateHandle): VM
}

/// An assisted factory's abstract method must return a type with an @AssistedInject-annotated constructor.

Would love to be able to do something similar:

@Inject lateinit var factory: StateViewModelFactory<MyViewModel>

[chrisjenx]

@gusuly0rum the work around right now isn’t ideal but not terrible.

I have a generic abstract factory:

interface StateViewModelFactory<VM : ViewModel> {
    fun create(handle: SavedStateHandle): VM
}

Then I just create a concrete factory for each one. Would be good to simpliy this down, but for the most part it’s just a one liner still:

@AssistedFactory
interface Factory : StateViewModelFactory<GroceryCheckoutVM>

[chrisjenx]

The whole point of the ticket is the AssistedInject doesn’t work…