@forivall/decorator

Simple function decorator/wrapping util, in typescript

Installation

npm install --save @forivall/decorator

Usage

Using the following wrapper function for our examples

function log<F extends (...args: any[]): any>(fn: F, label: string): F {
  return (...args: Parameters<F>) => {
    console.log(`enter ${label}`)
    const out: ReturnType<F> = fn(...args)
    console.log(`exit ${label}`)
    return out
  } as F
}

wrap()

import {wrap} from '@forivall/decorator'
const doStuff = wrap(log, () => console.log('stuff'), 'doStuff')
doStuff()
// Output:
// enter doStuff
// stuff
// exit doStuff

decorator()

Create a decorator function

import decorator from '@forivall/decorator'
const logDecorator = decorator(log)
class Stuff {
  @logDecorator('doStuff')
  doIt() {
    console.log('stuff')
  }
}
new Stuff().doIt()
// Output:
// enter doStuff
// stuff
// exit doStuff

proxied()

Add metadata to a function that proxies another. Useful for the proxy pattern.

class Stuff {
  doIt() {
    console.log('stuff')
  }
  somethingElse() {
    console.log('more stuff')
  }
}

import {proxied} from '@forivall/decorator'
class StuffWrapper {
  stuff = new Stuff()
}
interface StuffWrapper implements Stuff {}
Object.keys(Stuff.prototype).forEach((k) => {
  StuffWrapper.prototype[k] = proxied(Stuff, k, function(this: StuffWrapper, ...args: unknown[]) {
    return this.stuff[k](...args)
  })
})

Credits

Emily Marigold Klassen

License

ISC