Prem Rose premasagar

Building the Armory Bitcoin client for the Raspberry Pi

This is how I got Armory (etotheipi/BitcoinArmory; http://bitcoinarmory.com/) cross-compiled for the Raspberry Pi.

This is a great way to keep an air-gapped offline wallet for only $30 dollars for the RPi (that you can also use for other things; experiment, it's awesome) and $7 for a Class 10 4GB SD card, really easy to keep in a safe and secret place.

Dependencies

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written, the development of the Promises/A+ specification has made the original emphasis on Promises/A seem somewhat outdated.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 DOM builders like [domo][domo] trump HTML templates on the client.)

Like all web developers, I've used a lot of template engines. Like most, I've also written a few of them, some of which even [fit in a tweet][140].

The first open-source code I ever wrote was also one of the the first template engines for node.js, [a port][node-tmpl] of the mother of all JavaScript template engines, [John Resig][jresig]'s [micro-templates][tmpl]. Of course, these days you can't swing a dead cat without hitting a template engine; one in eight packages on npm ([2,220][npm templates] of 16,226 as of 10/19) involve templates.

John's implementation has since evolved and [lives on in Underscore.js][underscore], which means it's the default choice for templating in Backbone.js. And for a while, it's all I would ever use when building a client-side app.

But I can't really see the value in client-side HTML templates anymore.

	var fs = require('fs'), path = require('path');

	// Load all exported objects into a single module.
	fs.readdirSync(__dirname).forEach(function (filename) {
	var fullpath = path.join(__dirname, filename), resource,
	module;

	if (fullpath !== __filename && 'js' === fullpath.split('.').pop() && '.' !== fullpath[0]) {
	module = require(fullpath);
	exports[filename.split('.')[0]] = module;

	"use strict";

	// `f` is assumed to sporadically fail with `TemporaryNetworkError` instances.
	// If one of those happens, we want to retry until it doesn't.
	// If `f` fails with something else, then we should re-throw: we don't know how to handle that, and it's a
	// sign something went wrong. Since `f` is a good promise-returning function, it only ever fulfills or rejects;
	// it has no synchronous behavior (e.g. throwing).
	function dontGiveUp(f) {
	return f().then(
	undefined, // pass through success

	// Matraka's source code decoded and beautified
	// by @tlack
	//
	// Matraka is a 1005 byte Javascript "demo" by p01. It includes an 'evolving animation'
	// and great dirty synth music. View here:
	//
	// http://www.p01.org/releases/MATRAKA/matraka.png.html
	//
	// I fondly recall the demo scene of my youth, puzzling over the work of Future
	// Creators and those guys. I was puzzled by this worked so I had to figure it

	function round(num, decimalplaces){
	return Number(num.toFixed(decimalplaces));
	}

	function randomInt(length){
	return Math.ceil((length \|\| 2) * Math.random()) - 1;
	}

	function randomRange(min, max){
	return Math.random() * (max - min) + min;

	// e.g. scrollToTarget(document.getElementById('foo'));

	function offset(target){
	var left = 0,
	top = 0;

	while (target && target !== document.body){
	if (target.offsetLeft){
	left += target.offsetLeft;
	top += target.offsetTop;

	#! /bin/bash

	x=`identify -format "%w" $1`
	y=`identify -format "%h" $1`
	data=`openssl base64 < $1 \| tr -d '\n'`
	type=`file --mime-type -b $1`

	echo "display:block;
	font:0/0 a;
	color:transparent;

	Leave a comment if you'd like to speak at the Async International Show and Tell on Thursday 8th November.

	http://asyncjs.com