Observed<T>

Observed<T> is a class that wraps a value of type T and allows subscribers to be notified when the value is changed.

Observed variables are variables that can notify subscribers when their value changes. This can be useful in game development for tracking and responding to changes in various game states or variables. For example, an observed variable could be used to track the player's health, the progress of a loading screen, or the score of a game. Subscribers can be set up to listen for changes to the observed variable and take some action in response, such as updating a UI element or triggering some other event. Observed variables can be particularly useful in situations where multiple game objects or systems need to stay in sync with the value of a particular variable.

Adding Subscribers

Subscribers can be added using the Subscribe method, which takes an Action<T> delegate as an argument. This delegate will be called whenever the value of the Observed<T> instance is changed.

Observed<int> observedInt = new Observed<int>(0);
observedInt.Subscribe(value =>
{
    Console.WriteLine($"The value has changed to {value}");
});

Removing Subscribers

Subscribers can be removed using the Unsubscribe method, which takes an Action<T> delegate as an argument.

• Subscribe(Action<T> callback): Subscribes a callback function to the Observed<T> instance. The callback function will be called whenever the value of the Observed<T> instance changes.

• Unsubscribe(Action<T> callback): Unsubscribes a callback function from the Observed<T> instance. The callback function will no longer be called when the value of the Observed<T> instance changes.

Example

Observed<int> observedInt = new Observed<int>(0);

// Subscribe to receive updates when the value of observedInt changes
observedInt.Subscribe((newValue) => {
    Console.WriteLine($"observedInt changed to {newValue}");
});

// Set the value of observedInt and trigger the subscribed callback
observedInt.Value = 1; // Output: "observedInt changed to 1"

Setting the Value

The value of the Observed<T> instance can be set using the Value property. This will trigger the subscribers to be notified of the change.

observedInt.Value = 1; // Outputs "The value has changed to 1"

Conversion to and from T

The Observed<T> class includes implicit conversion operators for converting to and from the wrapped type T. This allows it to be used in place of T in most cases.

Observed<int> observedInt = new Observed<int>(0);
int value = observedInt;

Observed<int> observedInt2 = value;

Clearing Subscriptions

All subscribers can be removed at once using the ClearSubscriptions method.

observedInt.ClearSubscriptions();

Properties

SubscriberCount

Gets the number of subscribers registered for this observable.

HandleExceptions

A flag indicating whether exceptions thrown by subscribers should be handled or allowed to propagate.

Value

Gets or sets the current value of the observable. Setting the value will trigger the notification of subscribers if the value has changed.

Constructors

Observed()

Creates a new instance of the Observed class with a default value.

Observed(T initialValue)

Creates a new instance of the Observed class with the specified initial value.

Methods

Subscribe(Action<T> callback)

Registers a callback method to be notified when the value of the observable changes. If the callback method is already registered, it will not be added again.

Unsubscribe(Action<T> callback)

Unregisters a callback method from being notified when the value of the observable changes.