Class
Common
```kotlin
public class SnapshotStateObserver(private val onChangedExecutor: (callback: () -> Unit) -> Unit)
```
Helper class to efficiently observe snapshot state reads. See `observeReads` for more details.
NOTE: This class is not thread-safe, so implementations should not reuse observer between
different threads to avoid race conditions.
## Functions
observeReads
```kotlin
public fun observeReads(
scope: T,
onValueChangedForScope: (T) -> Unit,
block: () -> Unit,
)
```
Executes `block`, observing state object reads during its execution.
The `scope` and `onValueChangedForScope` are associated with any values that are read so that
when those values change, `onValueChangedForScope` will be called with the `scope` parameter.
Observation can be paused with `Snapshot.withoutReadObservation`.
#### Parameters
| | |
| --- | --- |
| scope | value associated with the observed scope. |
| onValueChangedForScope | is called with the `scope` when value read within `block` has been changed. For repeated observations, it is more performant to pass the same instance of the callback, as `observedScopeMaps` grows with each new callback instance. |
| block | to observe reads within. |
withNoObservations
```kotlin
public fun withNoObservations(block: () -> Unit)
```
Stops observing state object reads while executing `block`. State object reads may be
restarted by calling `observeReads` inside `block`.
clear
```kotlin
public fun clear(scope: Any)
```
Clears all state read observations for a given `scope`. This clears values for all
`onValueChangedForScope` callbacks passed in `observeReads`.
clearIf
```kotlin
public fun clearIf(predicate: (scope: Any) -> Boolean)
```
Remove observations using `predicate` to identify scopes to be removed. This is used when a
scope is no longer in the hierarchy and should not receive any callbacks.
start
```kotlin
public fun start()
```
Starts watching for state commits.
stop
```kotlin
public fun stop()
```
Stops watching for state commits.
notifyChanges
```kotlin
@TestOnly
public fun notifyChanges(changes: Set, snapshot: Snapshot)
```
This method is only used for testing. It notifies that `changes` have been made on
`snapshot`.
clear
```kotlin
public fun clear()
```
Remove all observations.