Please add promise example

[zmorris]

Hi, I'm trying to get Synchronize.js working with Inquirer but I've tried everything and can't get it to work with its promises:

package.json

{
  "dependencies": {
    "inquirer": "^3.0.6",
    "synchronize": "^2.0.0"
  }
}

index.js

const inquirer = require('inquirer');
const sync = require('synchronize');

const fiber = sync.fiber;
const await = sync.await;
const defer = sync.defer;

// // works
// inquirer.prompt([{
//     type: 'input',
//     name: 'first_name',
//     message: 'What\'s your first name'
// }]).then(function (answers) {
//   console.log('First name:', answers.first_name);
// });

// doesn't work
fiber(function() {
  const answers = await( 
    inquirer.prompt([{
      type: 'input',
      name: 'first_name',
      message: 'What\'s your first name'
    }]).then(defer())
  );

  console.log(answers);
});

$ yarn
$ node index.js
? What's your first name? Zack

/Users/zackmorris/Desktop/testing/appium-vynyl/node_modules/synchronize/sync.js:111
        fiber.throwInto(err)
              ^
[object Object]

I've tried every permutation, even variations of #41 but can't get it to work.

Can you update your documentation for promises? Or else show how to de-promisify something? I tried wrapping the promise in my own callback function to fit the form of your examples but it still didn't work for some reason.

---

By comparison, here's the same example with asyncawait and Inquirer:

package.json

{
  "dependencies": {
    "asyncawait": "^1.0.6",
    "inquirer": "^3.0.6"
  }
}

index.js

const async = require('asyncawait/async');
const await = require('asyncawait/await');
const inquirer = require('inquirer');

async (function () {
  const answers = await(
    inquirer.prompt([{
      type: 'input',
      name: 'first_name',
      message: 'What\'s your first name?'
    }])
  );

  console.log('First name:', answers.first_name);
})();

$ yarn
$ node index.js
? What's your first name? Zack
First name: Zack

Thanx!

[zakdav]

You can use or give a look to my module node-fibers-synchronize-helper that uses this module synchronize

index.js

const inquirer = require('inquirer');
var synchProm = require('node-fibers-synchronize-helper')

synchProm.executeSynch(function () {

 var answers = synchProm.executePromiseFiberFn(inquirer, inquirer.prompt, [{
     type: 'input',
     name: 'first_name',
     message: 'What\'s your first name'
}])

 console.log(answers);

}, function (err, res) {
if (err)
console.log("err", err)
else
console.log("OK:", res)
})

result:
davide@davide-kubuntu:~/node/test/synchronizeTests$ node .
? What's your first name davide
{ first_name: 'davide' }

You can give a look at my implementation

https://github.com/zakdav/node-fibers-synchronize-helper/blob/master/index.js

In your case i called this methods

var executePromiseFiberIntFn = function (obj, fn, params) {
var defer = sync.defer();
runPromiseFiberFn(obj, fn, params, defer)
var res = sync.await();
return res;
}

var runPromiseFiberFn = function (obj, fn, params, defer) {
fn.apply(obj, params).then(function (res) {
//fn().then(function (res) {
defer(null, res)
}).catch(function (e) {

    defer(e)
})

}

[dsandber]

So there isn't any "straight" (without additional code/helpers) way of calling inquirer using synchronize? I tried various permutations of await, defer(), etc, and also could never get it working.

[dreusel]

The problem is that then() will pass the result as the first argument, while defer(), generates a classical node-style callback which, like any classical node callback, expects any error as the first argument and the result as the second argument. This is a plain 'how to combine promises with callbacks' type of thing. Instead, try:

fiber(function() {
  // Create the defer first, otherwise await is called before the defer is created.
  const d = defer();
  const answers = await( 
    inquirer.prompt([{
      type: 'input',
      name: 'first_name',
      message: 'What\'s your first name'
    }]).then(r => d(null, r))
  );

  console.log(answers);
});

You could make things look slightly nicer by using nodes util.callbackify, but hopefully my example indicates more clearly what's actually happening.