Multiple Dispatch

mms for JavaScript and Node written in TypeScript

Installation

``sh
> yarn add multiple-dispatch
> npm install muiltiple-dispatch --save
`

Usage

`ts
import mm from 'multiple-dispatch';
import homeComponent from './components/home';
import * as store from './components/store';

const router = mm({
name: 'router dispatcher',
params: [
{
name: 'category',
// This is the default behaviour if you don't have 'isa'
isa: (dispatchedType: string, override: string) => dispatchedType === override
},
{
name: 'item',
isa: (dispatchedType: string, override: string) => dispatchedType === override
}
],
throw?: boolean;
});

// The 'types' are passed into the override handler, but don't need to be consumed
router.override(['home', 'main'], (category, item) => homeComponent);
router.override(['store', 'main'], () => store.main);
router.override(['store', 'drills'], () => store.drills);

router.dispatch('store', 'drills'); // Returns store.drills
router.dispatch('home', 'main'); // Returns homeComponent
router.dispatch('home', 'invalid'); // Returns null or throws

function requestHandler(params: { category: string, item: string }) {
return router.dispatch(params.category, params.item);
}

`

API

$3

Default export

`ts
import mm from 'multiple-dispatch'

function create(options: DispatchOptions): Dispatcher

interface Dispatcher {
name: string
override(types: TDispatch[], callback: (...types: TDispatch[]) => TReturn): boolean
dispatch(...types: TDispatch[]): TReturn | null
}

interface DispatchOptions {
name: string
params: Array<{ name: string; isa?: (special: TDispatch, general: TDispatch) => boolean }>

// Set to true if the desired behaviour is to throw exceptions with invalid usage or ambiguous dispatches.
throw?: boolean
}

interface DispatchHandler {
types: TDispatch[]
handler: (...types: TDispatch[]) => TReturn
}
`

#### isa function

The isa property in DispatchOptions is for determining if parameter types passed into dispatch has a matching
override DisatchHandler.

During the comparison, the SPECIAL types passed into dispatch(...) are compared against every set of GENERAL
types that exist. These are created when override(...) is called.

E.g.:

`ts

// 'home' and 'main' are the GENERAL type during the comparison
// ['home', 'main'] will be added to the DispatchHandler set.
// Every type 'set' that exists will be used during comparison to the find the BEST type match.

router.override(['home', 'main'], handler);

function (category: string, item: string) {

// category and item are the SPECIAL type
return router.dispatch(category, item);
}


`

$3

Dispatcher instance methods.
These can throw if throw is set to true in the DispatchOptions.

`ts
function override(types: string[], handler: DispatchHandler): boolean

function dispatch(...types: string[]): TReturn | null
``