ES7 Decorators

decorators.js

@ngInject('bus', '$ionicModal')
class Adder {
  constructor(num) {
    this.num = num
  }
  
  // order matters
  // if you @swallow first, then @log won't log caught exceptions
  @log
  @swallow
  @partial(100)
  add(...numbers) {
    if (numbers.includes(4)) throw new Error('I HATE 4')
    return this.num + numbers.reduce((x,y) => x + y, 0)
  }
}

console.log(Adder.$inject)
console.log((new Adder(10)).add(1, 2, 3))
console.log((new Adder(10)).add(4, 5, 6))




function ngInject(...deps) {
  return function(declaration) {
    declaration.$inject = deps
  }
}

function log(target, name, descriptor) {
  let fn = descriptor.value
  descriptor.value = function(...args) {
    console.log('Calling', name, 'with', args)
    try {
      let out = fn.apply(this, args)
      console.log('Got', out)
      return out
    }
    catch (e) {
      console.log('Caught', e.message)
      throw e
    }
  }
}

function swallow(t, n, descriptor) {
  let fn = descriptor.value
  descriptor.value = function(...args) {
    try {
      return fn.apply(this, args)
    }
    catch (e) {
      return 'nothing happened ;)'
    }
  }
}

function partial(...partialArgs) {
  return function(t, n, descriptor) {
    let fn = descriptor.value
    descriptor.value = function(...args) {
      return fn.apply(this, [...partialArgs, ...args])
    }
  }
}