Every game's data storage requirements are different. For this reason, Yarn Spinner is designed to make it straightforward to create your own custom component for managing how Yarn scripts store and load variables in ways that work with the other parts of your game.

Custom Variable Storage components are subclasses of the abstract class VariableStorageBehaviour. To implement your own, you need to implement the following methods:

public bool TryGetValue<T>(string variableName, out T result);
public void SetValue(string variableName, string stringValue);
public void SetValue(string variableName, float floatValue);
public void SetValue(string variableName, bool boolValue);
public void Clear();
public bool Contains(string variableName);

For a complete tutorial on how to build an entirely custom variable storage system, see Yarn Variables and Custom Variable Storage.

The In-Memory Variable Storage component is a Variable Storage component that stores all variables in memory. These variables are erased when the game stops.

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Variable Storage components are responsible for storing and retrieving the values of variables in your Yarn scripts. When a Yarn script needs to get the value of a variable, it asks the Variable Storage for it; when a Yarn script sets the value of a variable, the Variable Storage is given the value.

Each game has different requirements for how variables are stored, which means that Yarn Spinner doesn't make any assumptions how the information is actually stored on disk. Instead, you can create your own custom Variable Storage script that implements the methods that Yarn Spinner needs.

If you don't connect a Variable Storage to your Dialogue Runner, it will create an In-Memory Variable Storage when the game starts, and use that.