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# AddChangeListener(System.Action\<string, object>)

Method in [VariableStorageBehaviour](/api/csharp/yarn.unity/yarn.unity.variablestoragebehaviour.md)

## Summary

Registers a delegate that will be called when any variable is modified.

```csharp
public IDisposable AddChangeListener(System.Action<string, object> onChange)
```

## Parameters

| Name                              | Description                                          |
| --------------------------------- | ---------------------------------------------------- |
| `Action<string, object>` onChange | The delegate to run when the variable changes value. |

## Returns

An `System.IDisposable` that removes the registration when its `System.IDisposable.Dispose` method is called.