---
title: "SubcomposeLayoutState"
description: "State used by [SubcomposeLayout].

[slotReusePolicy] the policy defining what slots should be retained to be reused later."
type: "class"
---

<div class='type'>Class</div>


<a id='references'></a>

<div class='sourceset sourceset-common'>Common</div>


```kotlin
class SubcomposeLayoutState(private val slotReusePolicy: SubcomposeSlotReusePolicy)
```


State used by `SubcomposeLayout`.

`slotReusePolicy` the policy defining what slots should be retained to be reused later.


## Secondary Constructors

```kotlin
constructor() : this(NoOpSubcomposeSlotReusePolicy)
```


State used by `SubcomposeLayout`.


```kotlin
constructor(
    maxSlotsToRetainForReuse: Int
) : this(SubcomposeSlotReusePolicy(maxSlotsToRetainForReuse))
```


State used by `SubcomposeLayout`.

#### Parameters

| | |
| --- | --- |
| maxSlotsToRetainForReuse | when non-zero the layout will keep active up to this count slots which we were used but not used anymore instead of disposing them. Later when you try to compose a new slot instead of creating a completely new slot the layout would reuse the previous slot which allows to do less work especially if the slot contents are similar. |



## Functions

```kotlin
fun precompose(slotId: Any?, content: @Composable () -> Unit): PrecomposedSlotHandle
```


Composes the content for the given `slotId`. This makes the next scope.subcompose(slotId)
call during the measure pass faster as the content is already composed.

If the `slotId` was precomposed already but after the future calculations ended up to not be
needed anymore (meaning this slotId is not going to be used during the measure pass anytime
soon) you can use `PrecomposedSlotHandle.dispose` on a returned object to dispose the
content.

#### Parameters

| | |
| --- | --- |
| slotId | unique id which represents the slot to compose into. |
| content | the composable content which defines the slot. |


#### Returns

| | |
| --- | --- |
|  | `PrecomposedSlotHandle` instance which allows you to dispose the content. |



```kotlin
fun createPausedPrecomposition(
        slotId: Any?,
        content: @Composable () -> Unit,
    ): PausedPrecomposition
```


Creates `PausedPrecomposition`, which allows to perform the composition in an incremental
manner.

#### Parameters

| | |
| --- | --- |
| slotId | unique id which represents the slot to compose into. |
| content | the composable content which defines the slot.` |


#### Returns

| | |
| --- | --- |
|  | `PausedPrecomposition` for the given `slotId`. It allows to perform the composition in an incremental manner. Performing full or partial precomposition makes the next scope.subcompose(slotId) call during the measure pass faster as the content is already composed. |