Reactive Command Pattern Implementation

RxCommand is an Reactive Extensions (Rx) based abstraction for event handlers. It is based on ReactiveCommand for the ReactiveUI framework and RxCommand Flutter Package.

RxCommand capsules a given handler function that can then be executed by its execute method or directly call because it's a callable class. The result of this method is then published through its Observable interface. Additionally it offers Observables for it's current execution state, if the command can be executed and for all possibly thrown exceptions during command execution.

const command = RxCommand.create<int, string>((myInt) => "$myInt");

command.subscribe((s) => print(s)); // Setup the listener that now waits for events, not doing anything

// Somwhere else
command.execute(10); // the listener will print "10"

// or
command(10);

npm i rx-commands

An RxCommand is a generic class of type RxCommand<TParam = void, TResult = void> where TParam is the type of data that is passed when calling execute and TResult denotes the return type of the handler function. To signal that a handler doesn't take a parameter or returns a null value use void as type. Even if you create a RxCommand<void,void> you will receive a null value when the wrapped function finishes so you can listen for the successful completion.

An example of the declaration

RxCommand < string, List < WeatherEntry >> updateWeatherCommand;
RxCommand < bool, bool > switchChangedCommand;

• updateWeatherCommand expects a handler that takes a string as parameter and returns a List<WeatherEntry>.
• switchChangedCommand expects and returns a bool value.

You can create commands that are sync, async (returns promises) or from observables.

const commandSync = RxCommand.create((myInt) => "$myInt");
const commandNoResult = RxCommand.create<void>(() => {
	// Do Something
});
const commandNoParam = RxCommand.createNoParam<number>(() => {
	return 1;
});
const commandNoParamNoReturn = RxCommand.create<void, void>(() => {
	// Do something
});
const commandAsync = RxCommand.create(async () => {
	// do async
});
const commandFromObservable = RxCommand.create(() => of(1, 2, 3));

const command = RxCommand.create(() => {
    throw new Error("Something went wrong");
}, {
	restriction?: Observable<boolean>;
	emitInitialCommandResult?: boolean;
	emitLastResult?: boolean;
	emitsLastValueToNewSubscriptions?: boolean;
	initialLastResult?: TResult;
	debugName?: string;
});

All exceptions thrown by the wrapped function will be caught and redirected to throwExceptions observable. If you want to react on the, you can listen on the thrownException property.

const command = RxCommand.create(() => {
	throw new Error("Something went wrong");
});

command.thrownExceptions.subscribe((e) => {
	console.error(e);
});

See .github/CONTRIBUTING.md, then .github/DEVELOPMENT.md. Thanks! 💖

Filipe Santiago 💻 🖋 📖 🤔 🚇 🚧 📆 🔧

💝 This package was templated with create-typescript-app using the Bingo engine.