LocalClosureContainer

A DispatchClosure.Element, that handles local changes of a DispatchClosure.

Generally, this mechanism is not required to know in normal usage. However, it might be useful to introduce some new special mechanisms to the store.

LocalClosureContainer has following properties:

• It doesn't affect the closure that is a part of. Therefore, it must be accessed directly by DispatchClosure.local` to receive locally changed values. Original closure always remains the same.

• It works only for a time of dispatch call. Therefore, accessing it outside of dispatch function returns unchanged values.

• It's hierarchical. Nested dispatch calls receive accumulated local closures.

• Every change is identified by Slot.

These properties are not only determined by the implementation of this interface, but also by the convention. Therefore, it is important to use this mechanism according to the documentation and attached examples. Any local change should occur through withLocalClosure. Manual slots manipulation it's not recommended.

Interactions with a store

By default, store contains an instance of LocalClosureContainer (created by LocalClosureContainer()). It applies changes to the original closure field, so accessing local closure without local changes, returns values from the original one. Because local changes remains only for a time of dispatch call, accessing them from coroutines launched by a middleware, doesn't work.

Example

How to perform DispatchClosure change:

fun DispatchScope<*>.customDispatch(action: Action) {
   withLocalClosure(ClosureElement()) {
       dispatch(SomeAction)
   }
}

How to access changed values:

fun customMiddleware(): Middleware<AppState> = {
   var element = closure.local[ClosureElement] // outside of dispatch - returns values from the original closure
   dispatchFunction {
       element = closure.local[ClosureElement] // direct access to local closure in dispatch
                                              // properly returns local changes

       element = closure.local[ClosureElement]      // direct access to original closure
                                              // returns values from the original closure
   }
}