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Makes effects in composables more declarative #878

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Makes effects in composables more declarative #878

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8 changes: 5 additions & 3 deletions ...java/com/example/android/architecture/blueprints/todoapp/addedittask/AddEditTaskScreen.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -38,6 +38,7 @@ import androidx.compose.material.rememberScaffoldState
import androidx.compose.runtime.Composable
import androidx.compose.runtime.LaunchedEffect
import androidx.compose.runtime.getValue
import androidx.compose.runtime.rememberUpdatedState
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.res.dimensionResource
Expand Down Expand Up @@ -84,9 +85,10 @@ fun AddEditTaskScreen(
)

// Check if the task is saved and call onTaskUpdate event
LaunchedEffect(uiState.isTaskSaved) {
if (uiState.isTaskSaved) {
onTaskUpdate()
if (uiState.isTaskSaved) {
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Would this run on every recomposition, regardless of if uiState.isTaskSaved changed or not?

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Maybe this is answered here: https://stackoverflow.com/questions/69085027/difference-between-remember-and-rememberupdatedstate-in-jetpack-compose

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Yeah. This if statement will be check on every recomposition

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This is using recomposition as an observer of state change events to apply other changes to app state. Avoid this. Observe the state changes inside the LaunchedEffect instead so that it doesn't take one recomposition pass to apply currentOnTaskUpdate and then another to apply changes caused by that call.

val currentOnTaskUpdate by rememberUpdatedState(onTaskUpdate)
LaunchedEffect(Unit) {
currentOnTaskUpdate()
}
}

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8 changes: 5 additions & 3 deletions ...n/java/com/example/android/architecture/blueprints/todoapp/taskdetail/TaskDetailScreen.kt
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Expand Up @@ -36,6 +36,7 @@ import androidx.compose.material.rememberScaffoldState
import androidx.compose.runtime.Composable
import androidx.compose.runtime.LaunchedEffect
import androidx.compose.runtime.getValue
import androidx.compose.runtime.rememberUpdatedState
import androidx.compose.ui.Modifier
import androidx.compose.ui.res.dimensionResource
import androidx.compose.ui.res.stringResource
Expand Down Expand Up @@ -92,9 +93,10 @@ fun TaskDetailScreen(
}

// Check if the task is deleted and call onDeleteTask
LaunchedEffect(uiState.isTaskDeleted) {
if (uiState.isTaskDeleted) {
onDeleteTask()
if (uiState.isTaskDeleted) {
val currentOnDeleteTask by rememberUpdatedState(onDeleteTask)
LaunchedEffect(Unit) {
currentOnDeleteTask()
}
}
}
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