waterfall to promises

promises.coffee

Promise = require 'bluebird'

methodB = ->
  p = new Promise (resolve, reject)->
    setTimeout ->
      console.log 'doing methodB'
      reject 'failed b'
    , 1000
  p.catch (e)->
    console.log 'log error to methodB.log'
  p
  
  
methodC = ->
  p = new Promise (resolve, reject)->
    setTimeout ->
      console.log 'methodC'
      reject 'failed c'
    , 1000
  p.catch (e)->
    console.log 'log error to methodC.log'
  p
  

methodA = ->
  console.log 'doing methodA'
  methodB()
  .catch (e)->
    console.log "log that A needs B to execute"
    Promise.reject e
  .then -> 
    methodC().catch (e) ->
      console.log "log that A needs C to execute"

methodA().catch (e)->
  console.log 'error doing A warn client'

###
doing methodA
doing methodB
log error to methodB.log
log that A needs B to execute
error doing A warn client
###

promises.js

// Generated by CoffeeScript 1.6.3
(function() {
  var Promise, methodA, methodB, methodC;

  Promise = require('bluebird');

  methodB = function() {
    var p;
    p = new Promise(function(resolve, reject) {
      return setTimeout(function() {
        console.log('methodB');
        return reject('failed b');
      }, 1000);
    });
    p["catch"](function(e) {
      console.log('log error to methodB.log');
      return e;
    });
    return p;
  };

  methodC = function() {
    var p;
    p = new Promise(function(resolve, reject) {
      return setTimeout(function() {
        console.log('methodC');
        return reject('failed c');
      }, 1000);
    });
    p["catch"](function(e) {
      console.log('log error to methodC.log');
      return e;
    });
    return p;
  };

  methodA = function() {
    console.log('doing methodA');
    return methodB()["catch"](function(e) {
      console.log('something failed on b');
      return Promise.reject(e);
    }).then(function() {
      console.log('going for c');
      return methodC()["catch"](function(e) {
        console.log("something failed c");
        return Promise.reject(e);
      });
    });
  };

  methodA();

  /*
  methodB
  methodB failed handler
  hoge
  */


}).call(this);

waterfall.coffee

methodA (callback)->
  async.waterfall [
    (next)->
      methodB (e)->
        if e
          # methodB failed handler
          next e
        do next
    (next)->
      methodC (e)->
        if e
          # methodC failed handler
          next e
        do next
  ], (e)->
    return callback e if e
    do callback