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persisting_state_of_components.md: Clarify recommendation for SerializablePersistentStateComponent since 2022.2

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Karol Lewandowski 2025-04-03 12:49:17 +02:00
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topics/basics/persisting_state_of_components.md
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@ -36,13 +36,18 @@ If an extension needs to have a persistent state, define a separate service resp
The recommended approach to implementing a persistent state component in Kotlin is to extend one of the base classes:
1. [`SimplePersistentStateComponent`](#SimplePersistentStateComponent)
2. [`SerializablePersistentStateComponent`](#SerializablePersistentStateComponent) (available since 2022.2)
2. [`SerializablePersistentStateComponent`](#SerializablePersistentStateComponent) (available and recommended since 2022.2)
Both classes implement [`PersistentStateComponentWithModificationTracker`](%gh-ic%/platform/projectModel-api/src/com/intellij/openapi/components/PersistentStateComponentWithModificationTracker.java) and track modifications count internally (in most cases; see details below).
The `getStateModificationCount()` method helps avoid calling `PersistentStateComponent.getState()` to check whether the state is changed and must be saved.
<chapter title="SimplePersistentStateComponent" id="SimplePersistentStateComponent">
[`SimplePersistentStateComponent`](%gh-ic%/platform/projectModel-api/src/com/intellij/openapi/components/SimplePersistentStateComponent.kt) is parameterized by a subclass of [`BaseState`](%gh-ic%/platform/projectModel-api/src/com/intellij/openapi/components/BaseState.kt).
`BaseState` provides a set of handy [property delegates](https://kotlinlang.org/docs/delegated-properties.html), which make it easy to create properties with default values.
In addition, delegates track property modifications internally, which helps decrease calling `PersistentStateComponent.getState()` by the platform.
Delegates track simple property modifications internally.
Note that incremental collection modification (adding, removing, or modifying collection objects) may require manual `BaseState.incrementModificationCount()` invocation (see its Javadoc for details).
Example:
@ -66,6 +71,8 @@ class MySettings : SimplePersistentStateComponent<MySettings.State>(State()) {
State properties are exposed for reading and modification via persistent state component class' properties.
The state properties are modified by copying the state and overwriting a modified value within `SerializablePersistentStateComponent.updateState()`, which ensures atomic modification and thread safety.
The copy-on-write approach allows for full internal modification tracking.
Example:
```kotlin