Add performAction function to ReEngagePrompt

[luizgrp]

WHAT

Add performAction function to ReEngagePrompt.
Add sample.

WHY

So it can be used with custom prompts.

Checklist 📋

• Add explicit visibility modifier and explicit return types for public declarations
• Run spotless check
• Run tests
• Update metalava's signature text files

[yschimke]

I understand this is correct and our guidance, it does create a lot of visual noise.

Do we know why apps like Now in Android don't follow the guidance?

https://github.com/android/nowinandroid/blob/76d0e430f7d350b1707bb19c8e007bc5679ac729/feature/bookmarks/src/main/kotlin/com/google/samples/apps/nowinandroid/feature/bookmarks/BookmarksViewModel.kt

[luizgrp]

I don't know, what about asking in https://github.com/android/nowinandroid/discussions ?

[luizgrp]

android/nowinandroid#1235

[luizgrp]

The answer seems to be in DAC:

Flow APIs allow for this with the started argument in the stateIn method.

Which seems to be what NiA is using.

Then it continues:

In the cases where this is inapplicable, define an idempotent initialize() function to explicitly start the state production pipeline as shown in the following snippet:

So we should re-evaluate our cases and see when the stateIn + started WhileSubscribed is applicable.

[luizgrp]

#2080

[yschimke]

For a follow up. Are there ways to reduce the repetition of this initialise phase?

[luizgrp]

This is the repetition:

Composable

        SideEffect {
            viewModel.initialize()
        }

ViewModel

        private var initializeCalled = false

        @MainThread
        fun initialize() {
            if (initializeCalled) return
            initializeCalled = true

            // pipeline initialization
        }

The repetition could be reduced having a base class for VM, but that's not scalable. I don't see many lines saved if composition approach is taken instead of inheritance.

For the composable, there is only 3 lines, that could be inlined.

Any thoughts?

[yschimke]

Nothing for us. If the guidance is good, the library should build this in.

But it seems very optional.