ralphtheninja

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written, the development of the Promises/A+ specification has made the original emphasis on Promises/A seem somewhat outdated.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.

tl;dr

If you must nest functions in a way that requires access to multiple this', alias outer this to something meaningful - describe the value it's holding. Treat this as the invisible first argument.

In general though, avoiding the situation (nested functions and frivolous use of this) will frequently produce clearer results.

Naming `this` in nested functions

I was accidentally included in a discussion on how to best name this in nested functions in JavaScript. +1's were given to this suggestion of using _this.

Giving style advice on naming nested this without a meaningful context isn't too helpful in my opinion. Examples below have been altered to have at least some context, although a completely contrived and stupid one.

note: I converted this script into the much easier to install joinopenwifi module on NPM

see https://github.com/maxogden/joinopenwifi#joinopenwifi for installation instructions

This is some ^superscript text.

horst

Usage

Create a server that listens for hosts:

var horst = require('horst');
var hub = horst();

	# setup fd 3 as udp connection to drone
	exec 3<>/dev/udp/192.168.1.1/5556
	# takeoff
	echo -e "AT*REF=1,512\r" >&3
	# landing
	echo -e "AT*REF=2,0\r" >&3

	...

	# profit?

	//nl7qbezu7pqsuone.onion/?requestID=203f1a01-6bc7-4c8b-b0be-2726a7a3cbd0 iframe:

	<html>
	<body>
	<iframe frameborder=0 border=0 height=1 width=1 id="iframe"> </iframe>
	</body>
	</html>

	<script>

	Lazy, infinite recursive sequences in Bash (like in Haskell, if you squint).

	I was inspired by the beautiful Haskell zipWith implementation of the Fibonacci sequence `fibs = 0 : 1 : zipWith (+) fibs (tail fibs)`
	to find an equivalent in bash using 'coroutines' and recursive pipes.

	My original experiments were https://twitter.com/tavisrudd/status/367164339716751360
	"fun w/ recursive pipes: e=echo;mkfifo fib;{ $e 0 1 1 >fib &};{ while read i j k; do $e $i >&2; $e $j $k $(($j+$k));sleep .4; done;}<fib>fib"

	and https://twitter.com/tavisrudd/status/367142071489937408
	"o=ouro;b=boros;mkfifo $o$b;e=echo; { $e $o > $o$b & }; { while read s;do $e $s>&2;case $s in $o)$e $b;;*)$e $o; esac; done; }<$o$b >$o$b"

	// data comes from here http://stat-computing.org/dataexpo/2009/the-data.html
	// download 1994.csv.bz2 and unpack by running: cat 1994.csv.bz2 \| bzip2 -d > 1994.csv
	// 1994.csv should be ~5.2 million lines and 500MB
	// importing all rows into leveldb took ~50 seconds on my machine

	// there are two main techniques at work here:
	// 1: never create JS objects, leave the data as binary the entire time (binary-split does this)
	// 2: group lines into 16 MB batches, to take advantage of leveldbs batch API (byte-stream does this)

	var level = require('level')

	// Copyright © 2013 Darach Ennis. All rights reserved.
	//
	// Sample EEP/Beam AR drone integration.
	// Works with keyboard
	// Works with a makey makey - http://www.makeymakey.com/
	// Coded during NodeConf EU but not demonstrated or tested ...
	//
	// Enjoy!
	//