Remove `LayoutViewFactory` + refactor `FeatureView` to make it compose-first. by alexanderbezverhni · Pull Request #511 · instacart/formula

alexanderbezverhni · 2026-05-19T17:52:46Z

Remove LayoutViewFactory + refactor FeatureView to make it compose-first.

Also, as a side effect of LayoutViewFactory removal:

update Tasks sample app to use Compose
fold formula-android-compose module into formula-android

Why do we stop supporting Android Views?

…rst.

carrotkite · 2026-05-19T17:57:27Z

	1 Warning
⚠️	No coverage data found for com/instacart/formula/android/ViewFactory

JaCoCo Code Coverage 93.79% ✅

Class	Covered	Meta	Status
`com/instacart/formula/android/ViewFactory`	No coverage data found : -%	No coverage data found : -%	🃏
`com/instacart/formula/android/RouteEnvironment`	100%	0%	✅
`com/instacart/formula/android/FeatureFactory`	100%	0%	✅
`com/instacart/formula/android/FormulaFragment`	50%	0%	✅
`com/instacart/formula/android/ComposeViewFactory`	100%	0%	✅

Generated by 🚫 Danger

olive-agent · 2026-05-19T17:58:06Z

-        return featureView.view
+        val state = mutableStateOf(featureView.initialModel)
+        this.outputState = state
+        return ComposeView(requireContext()).apply {


This changes the framework's error-handling contract for render failures. routeDelegate.setOutput(...) is still wrapped in try/catch, but the actual UI work now happens later inside ComposeView.setContent { ... }, so exceptions thrown during composition/recomposition will bypass RouteEnvironment.onScreenError. The updated test suite explicitly expects that behavior, which means apps that currently rely on onScreenError for screen-level crash reporting or recovery lose it silently. Was that intended? If not, we need a way to preserve the old reporting path for render-time failures before landing this refactor.

This actually changes nothing for the upstream app, given it was not using LayoutViewFactory. RouteEnvironment.onScreenError was meaningful in LayoutViewFactory since synchronous and imperative android.view.View setup could throw:

null findViewById

NPE on a missing field

adapter blowing up

ComposeViewFactory, on other hand, both before and after the changes, is just changing a MutableState variable, while the actual rendering happens later, inside Compose recomposition, outside
try/catch.

So onScreenError no longer catches the kind of error it was originally designed for. We should think of an alternative approach here, which is out of scope for this PR.

carrotkite · 2026-05-19T18:01:49Z

	1 Warning
⚠️	⚠️ Performance regressions detected in benchmarks

📊 Benchmark Comparison Report

Summary

Regressions: 4 ⚠️
Improvements: 0
Unchanged: 21

⚠️ Performance Regressions

Benchmark	Baseline	Current	Change
com.instacart.formula.benchmarks.TransitionBenchmark.transitions (depth=0)	11.479 ± 0.044 us/op	12.933 ± 0.076 us/op	+12.7% 🔴
com.instacart.formula.benchmarks.ActionCountBenchmark.stateChanges (actionCount=25)	11.888 ± 0.036 us/op	13.261 ± 0.119 us/op	+11.5% 🔴
com.instacart.formula.benchmarks.CallbackOverheadBenchmark.transitions (callbackCount=10)	11.956 ± 0.134 us/op	13.305 ± 0.141 us/op	+11.3% 🔴
com.instacart.formula.benchmarks.TransitionBenchmark.transitions (depth=10)	11.785 ± 0.072 us/op	13.001 ± 0.174 us/op	+10.3% 🔴

No significant changes (21 benchmarks)

Benchmark	Baseline	Current	Change
com.instacart.formula.benchmarks.ActionCountBenchmark.stateChanges (actionCount=1)	11.554 ± 0.048 us/op	12.599 ± 0.071 us/op	+9.0%
com.instacart.formula.benchmarks.ActionCountBenchmark.stateChanges (actionCount=100)	12.96 ± 0.158 us/op	14.08 ± 0.186 us/op	+8.6%
com.instacart.formula.benchmarks.ActionInitializationBenchmark.initializeNewActions (actionCount=1)	0.631 ± 0.058 us/op	0.686 ± 0.044 us/op	+8.6%
com.instacart.formula.benchmarks.ActionInitializationBenchmark.initializeNewActions (actionCount=100)	11.076 ± 0.156 us/op	10.684 ± 0.074 us/op	-3.5%
com.instacart.formula.benchmarks.ActionInitializationBenchmark.initializeNewActions (actionCount=25)	3.234 ± 0.034 us/op	3.089 ± 0.08 us/op	-4.5%
com.instacart.formula.benchmarks.CallbackInitializationBenchmark.initializeNewCallbacks (callbackCount=10)	1.526 ± 0.287 us/op	1.582 ± 0.279 us/op	+3.7%
com.instacart.formula.benchmarks.CallbackInitializationBenchmark.initializeNewCallbacks (callbackCount=50)	5.519 ± 1.031 us/op	5.428 ± 0.575 us/op	-1.6%
com.instacart.formula.benchmarks.CallbackOverheadBenchmark.transitions (callbackCount=50)	13.654 ± 0.45 us/op	14.615 ± 0.527 us/op	+7.0%
com.instacart.formula.benchmarks.ChildrenCountBenchmark.stateChanges (childrenCount=1)	11.585 ± 0.042 us/op	12.584 ± 0.085 us/op	+8.6%
com.instacart.formula.benchmarks.ChildrenCountBenchmark.stateChanges (childrenCount=100)	13.66 ± 0.182 us/op	14.965 ± 0.146 us/op	+9.6%
com.instacart.formula.benchmarks.ChildrenCountBenchmark.stateChanges (childrenCount=25)	12.084 ± 0.092 us/op	13.142 ± 0.305 us/op	+8.7%
com.instacart.formula.benchmarks.ChildrenInitializationBenchmark.initializeNewChildren (childrenCount=1)	0.618 ± 0.04 us/op	0.688 ± 0.055 us/op	+11.3%
com.instacart.formula.benchmarks.ChildrenInitializationBenchmark.initializeNewChildren (childrenCount=100)	12.28 ± 0.11 us/op	12.405 ± 1.059 us/op	+1.0%
com.instacart.formula.benchmarks.ChildrenInitializationBenchmark.initializeNewChildren (childrenCount=25)	3.329 ± 0.084 us/op	3.278 ± 0.046 us/op	-1.5%
com.instacart.formula.benchmarks.GlobalEffectQueueBenchmark.measure100Effects	8.122 ± 0.645 us/op	8.2 ± 0.185 us/op	+1.0%
com.instacart.formula.benchmarks.GlobalEffectQueueBenchmark.measure10Effects	0.697 ± 0.005 us/op	0.639 ± 0.069 us/op	-8.3%
com.instacart.formula.benchmarks.GlobalEffectQueueBenchmark.measure1Effect	0.056 ± 0.0 us/op	0.052 ± 0.001 us/op	-6.8%
com.instacart.formula.benchmarks.TransitionBenchmark.transitions (depth=20)	12.391 ± 0.079 us/op	13.284 ± 0.073 us/op	+7.2%
com.instacart.formula.benchmarks.TransitionQueueBenchmark.measure1	0.32 ± 0.016 us/op	0.339 ± 0.018 us/op	+5.9%
com.instacart.formula.benchmarks.TransitionQueueBenchmark.measure100	0.324 ± 0.014 us/op	0.338 ± 0.008 us/op	+4.3%
com.instacart.formula.benchmarks.TransitionQueueBenchmark.measure10000	0.325 ± 0.004 us/op	0.347 ± 0.004 us/op	+6.8%

Regressions: ±10% with non-overlapping confidence intervals. Improvements: ±10% change only.

Generated by 🚫 Danger

Jawnnypoo · 2026-05-19T18:53:45Z

Should bump to 0.9.0 with this one

alexanderbezverhni · 2026-05-19T20:46:26Z

-import com.instacart.formula.android.FeatureView
-import com.instacart.formula.android.ViewFactory
-
-abstract class ComposeViewFactory<RenderModel : Any> : ViewFactory<RenderModel> {


Now, when Compose is first class citizen in formula-android, no need to keep a separate formula-android-compose dependency with a single ComposeViewFactory class. Folding it into formula-android.

alexanderbezverhni · 2026-05-19T20:56:52Z

-    val view: View,
-    val setOutput: (RenderModel) -> Unit,
+    val content: @Composable (RenderModel) -> Unit,
+    val initialModel: RenderModel? = null,


Removing unneeded android.view.View field from FeatureView.

alexanderbezverhni · 2026-05-19T21:01:06Z

-    private var featureView: FeatureView<Any>? = null
+    private var outputState: MutableState<Any?>? = null


No need to keep FeatureView around anymore, for setting new output.

alexanderbezverhni · 2026-05-19T21:03:31Z

+            // Based-on: https://developer.android.com/develop/ui/compose/migrate/interoperability-apis/compose-in-views#compose-in-fragments
+            setViewCompositionStrategy(ViewCompositionStrategy.DisposeOnViewTreeLifecycleDestroyed)
+            setContent {
+                state.value?.let { featureView.content(it) }
+            }


Moving androidx.compose.ui.platform.ComposeView creation from ComposeViewFactory directly to FormulaFragment.

Alternative navigation host (Compose Nav 3) doesn't need ComposeView to render the content.

alexanderbezverhni · 2026-05-19T21:06:37Z

-        return flow<Unit> { delay(5.seconds) }.flatMapLatest { localStore }
+        return flow {
+            delay(5.seconds)
+            emit(Unit)
+        }.flatMapLatest { localStore }


Fixing unrelated bug that was introduced here: #430

This flow was never emitting, resulting in Tasks app never showing tasks:

alexanderbezverhni · 2026-05-19T21:07:28Z

+import com.examples.todoapp.R
+import com.instacart.formula.invoke
+
+private val TodoColors = lightColors(


Migrating Tasks demo app from LayoutViewFactory to ComposeViewFactory.

Few screenshots AFTER:

1 2 3

FrancoisBlavoet

nice

the announcement of Android being Compose first is good timing for formula to remove its view integration 🙌

Laimiux · 2026-05-20T15:29:50Z

        assertVisibleContract(TestKey())
    }

-    @Test fun `notify fragment environment if setOutput throws an error`() {


Not valid test anymore?

Yes - TestViewFactory was extending LayoutViewFactory, which propagated view binding exceptions to RouteEnvironment.onScreenError. With ComposeViewFactory, rendering happens within compose recomposition, so we need to think of an alternative mechanism to catch/report rendering errors there.

More in this comment:
#511 (comment)

Laimiux · 2026-05-20T15:43:52Z

+ */
+abstract class ComposeViewFactory<RenderModel : Any> : ViewFactory<RenderModel> {
+
+    final override fun create(params: ViewFactory.Params): FeatureView<RenderModel> {


I'm not sure if we need FeatureView and ViewFactory separation from ComposeViewFactory. With this change FeatureView already leaks compose APIs into ViewFactory. I'm wondering if we could do the following

Maybe this a little convoluted, but I do see value in keeping an agnostic ViewFactory , but maybe it should be a sealed interface

// Package: com.instacart.formula.android

sealed interface ViewFactory<Output : Any>

// Package: com.instacart.formula.android - for sealed hierarchy to work, needs to be in same package.

abstract class ComposeViewFactory<Output : Any> : ViewFactory<Output>

// Package: com.instacart.formula.android.compose

@Deprecated() typealias ComposeViewFactory<Output : Any> = RealComposeViewFactory<Output>

Good point about the leakage. I'm skeptical about agnostic ViewFactory value, given "Android is Compose-first", but I can give this proposal a shot. Either way, would you agree that FeatureView should be eliminated as a redundant abstraction?

Yeah, I don't think it provides any value anymore.

Laimiux · 2026-05-20T19:34:27Z

- * @param view The root Android view.
- * @param setOutput A function called to apply [RenderModel] to the view.
- */
-class FeatureView<RenderModel>(


Laimiux · 2026-05-20T19:43:12Z

        get() = environment.routeDelegate

-    private var featureView: FeatureView<Any>? = null
+    private var outputState: MutableState<Any?>? = null


Hmm, I'm wondering if some of this logic should be simplified. I don't think we need outputState to be nullable. Maybe we can make it a val and create it on initialization. We could consolidate val output: Any? = null into it.

tryToSetState might be redundant.

In the onCreateView, we could have

val initial: Any? = when (viewFactory) { is ComposeViewFactory -> viewFactory.initialModel() } setContent { val output = outputState.value ?: initial if (output != null) { routeDelegate.Content(formulaRouteId, viewFactory, output) } }

Great suggestion - done

Laimiux

Looks great

Remove LayoutViewFactory + refactor FeatureView to make it compose-fi…

4fc15c1

…rst.

alexanderbezverhni self-assigned this May 19, 2026

olive-agent Bot reviewed May 19, 2026

View reviewed changes

olive-agent Bot added the reviewed-by-olive label May 19, 2026

alexanderbezverhni added 3 commits May 19, 2026 12:50

same as before

2ce321c

fix repo never firing

867d15d

update CI

c50a24c

alexanderbezverhni commented May 19, 2026

View reviewed changes

remove unneeded test

9b91e9e

alexanderbezverhni commented May 19, 2026

View reviewed changes

Trigger build.

f64d69b

alexanderbezverhni marked this pull request as ready for review May 19, 2026 21:26

alexanderbezverhni changed the title ~~Remove LayoutViewFactory + refactor FeatureView to make it compose-first.~~ Remove LayoutViewFactory + refactor FeatureView to make it compose-first. May 19, 2026

alexanderbezverhni requested a review from Laimiux May 19, 2026 21:27

FrancoisBlavoet approved these changes May 19, 2026

View reviewed changes

Laimiux reviewed May 20, 2026

View reviewed changes

Get rid of FeatureView and make ViewFactory a sealed interface.

116eb76

alexanderbezverhni requested a review from Laimiux May 20, 2026 18:57

Laimiux reviewed May 20, 2026

View reviewed changes

Simplify FormulaFragment.

836c0f3

Laimiux approved these changes May 20, 2026

View reviewed changes

Laimiux merged commit 4f39702 into master May 20, 2026
8 checks passed

Laimiux deleted the bezverhni/feature_view_refactor branch May 20, 2026 20:11

jbingham17 mentioned this pull request Jun 15, 2026

Remove LayoutViewFactory + refactor FeatureView to make it compose-first. coderabbit-demo/formula#1

Open

This was referenced Jun 15, 2026

Remove LayoutViewFactory + refactor FeatureView to make it compose-first iantybo/formula#1

Open

Remove LayoutViewFactory + refactor FeatureView to make it compose-first (first commit) iantybo/formula#2

Open

		private var featureView: FeatureView<Any>? = null
		private var outputState: MutableState<Any?>? = null

Uh oh!

Conversation

alexanderbezverhni commented May 19, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Why do we stop supporting Android Views?

Uh oh!

carrotkite commented May 19, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

JaCoCo Code Coverage 93.79% ✅

Uh oh!

olive-agent Bot May 19, 2026

Choose a reason for hiding this comment

Uh oh!

alexanderbezverhni May 19, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

carrotkite commented May 19, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

📊 Benchmark Comparison Report

Summary

⚠️ Performance Regressions

Uh oh!

Jawnnypoo commented May 19, 2026

Uh oh!

alexanderbezverhni May 19, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

FrancoisBlavoet left a comment

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Laimiux left a comment

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

5 participants

alexanderbezverhni commented May 19, 2026 •

edited

Loading

carrotkite commented May 19, 2026 •

edited

Loading

alexanderbezverhni May 19, 2026 •

edited

Loading

carrotkite commented May 19, 2026 •

edited

Loading

alexanderbezverhni May 19, 2026 •

edited

Loading