---
title: "HostDefaultKey"
description: "A type-safe identifier used to define a key for retrieving default values from the hosting
environment.

This key is strictly required by [compositionLocalWithHostDefaultOf] to establish a mapping
between a [CompositionLocal] and a value provided by the host (via the internal
[HostDefaultProvider])."
type: "interface"
---

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


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

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



```kotlin
public interface HostDefaultKey<T>
```


A type-safe identifier used to define a key for retrieving default values from the hosting
environment.

This key is strictly required by `compositionLocalWithHostDefaultOf` to establish a mapping
between a `CompositionLocal` and a value provided by the host (via the internal
`HostDefaultProvider`).

#### Parameters

| | |
| --- | --- |
| T | The type of the value associated with this key. |