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StateObject type since v0.2

A dependency that provides a single stateful value; the dependency updates when the value changes state.

Dependency & {
    type: "State",
    kind: string,
    get: (self, asDependency: boolean?) -> T


  • type - uniquely identifies state objects for runtime type checks
  • kind - holds a more specific type name for different kinds of state object


since v0.1


Returns the current value stored in the state object.

If dependencies are being captured (e.g. inside a computed callback), this state object will also be added as a dependency.

(asDependency: boolean?) -> T

Example Usage

-- these are examples of objects which are state objects
local computed: StateObject = Computed(function()
    return "foo"
local observer: StateObject = Observer(computed)

Automatic Dependency Manager

Fusion includes an automatic dependency manager which can detect when graph objects are used in certain contexts and automatically form reactive graphs.

In order to do this, state objects should signal to the system when they are being used. This can be done via the useDependency() function internally, which should be called with the state object as the argument during execution of the :get() method.

Furthermore, to help assist the dependency manager prevent cycles in the reactive graph, state objects should register themselves with the system as soon as they are created via the initDependency() function internally. This is primarily used to prevent dependencies from being captured when they originate from within the object which is doing the capturing.

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