Trevor Delamorandiere tdelam

This article has been given a more permanent home on my blog. Also, since it was first written, the development of the Promises/A+ specification has made the original emphasis on Promises/A seem somewhat outdated.

You're Missing the Point of Promises

Promises are a software abstraction that makes working with asynchronous operations much more pleasant. In the most basic definition, your code will move from continuation-passing style:

getTweetsFor("domenic", function (err, results) {
 // the rest of your code goes here.

	controller.on('conversationStarted', (bot, convo) => {
	console.log('A conversation started with ', convo.context.user);
	// Map the convo when it starts with the proper user
	// and set `quote_completed` to false. This is useful for
	// resuming a quote. This is set to true with convo.on('end') callback
	if (convo.status === 'active') {
	const usersPublicProfile = 'https://graph.facebook.com/v2.6/' + convo.context.user + '?fields=first_name,last_name,&access_token=' + process.env.page_token;
	request({
	url: usersPublicProfile,
	json: true // parse

	[debug] Simple CORS request from Origin 'http://localhost:3000' is allowed
	[debug] Processing by PhoenixChat.UserController.create/2
	Parameters: %{"user" => %{"email" => "[email protected]", "password" => "[FILTERED]", "username" => "tdelam"}}
	Pipelines: [:api]
	[info] Sent 500 in 47ms
	[error] #PID<0.353.0> running PhoenixChat.Endpoint terminated
	Server: localhost:4000 (http)
	Request: POST /api/users
	** (exit) an exception was raised:
	** (FunctionClauseError) no function clause matching in Ecto.Changeset.cast_key/1

	For C#[##]-DW##-MP###[-D][d]
	C\d\[\d{2}\]-[A-Z]W\d{2}-MP\d{3}\[-[A-Z]\]\[[a-z]\]

	For B#[##]-FD###-FL###[-D][d]:
	B\d\[\d{2}\]-F[A-Z]\d{3}-FL\d{3}\[-[A-Z]\]\[[a-z]\]

	For T#[##]-MP###[-D][d]
	T\d\[\d{2}\]-MP\d{3}\[-[A-Z]\]\[[a-z]\]

	Characters in [ ] are optional

	# Project: Catalogue fun
	# Author: Trevor Delamorandiere,2012
	#

	import os
	import base64

	from django.conf import settings

	from search.models import SearchTerm

	ARCHFLAGS=-arch x86_64
	Apple_PubSub_Socket_Render=/tmp/launch-P4hAVq/Render
	CFLAGS=-Qunused-arguments
	CPPFLAGS=-Qunused-arguments
	DISPLAY=/tmp/launch-TfyrF7/org.macosforge.xquartz:0
	GEM_HOME=/Users/trevor/.rvm/gems/ruby-2.0.0-p353
	GEM_PATH=/Users/trevor/.rvm/gems/ruby-2.0.0-p353:/Users/trevor/.rvm/gems/ruby-2.0.0-p353@global
	GREP_COLOR=1;32
	GREP_OPTIONS=--color=auto --exclude-dir=.cvs --exclude-dir=.git --exclude-dir=.hg --exclude-dir=.svn
	HOME=/Users/trevor

	➜ bodhi git:(master) cat /Users/trevor/.rvm/log/1399059150_ruby-1.9.3-p545/configure.log
	configure: WARNING: unrecognized options: --without-tcl, --without-tk
	checking build system type... x86_64-apple-darwin13.1.0
	checking host system type... x86_64-apple-darwin13.1.0
	checking target system type... x86_64-apple-darwin13.1.0
	checking whether the C compiler works... no
	configure: error: in `/Users/trevor/.rvm/src/ruby-1.9.3-p545':
	configure: error: C compiler cannot create executables
	See `config.log' for more details


	➜ ~ cat /Users/trevor/.rvm/src/ruby-1.9.3-p545/config.log
	This file contains any messages produced by compilers while
	running configure, to aid debugging if configure makes a mistake.

	It was created by configure, which was
	generated by GNU Autoconf 2.69. Invocation command line was

	$ ./configure --prefix=/Users/trevor/.rvm/rubies/ruby-1.9.3-p545 --with-opt-dir=/usr/local/opt/libyaml:/usr/local/opt/readline:/usr/local/opt/libksba:/usr/local/opt/openssl --without-tcl --without-tk --disable-install-doc --enable-shared

	➜ src rvm install 1.9.3
	Searching for binary rubies, this might take some time.
	No binary rubies available for: osx/10.9/x86_64/ruby-1.9.3-p545.
	Continuing with compilation. Please read 'rvm help mount' to get more information on binary rubies.
	Checking requirements for osx.
	==> Upgrading 3 outdated packages, with result:
	libyaml 0.1.6, openssl 1.0.1g, readline 6.3.3
	==> Upgrading libyaml
	==> Downloading https://downloads.sf.net/project/machomebrew/Bottles/libyaml-0.1.6.mavericks.bottle.tar.gz
	######################################################################## 100.0%