“...I've been working since 2008 with Ruby / Ruby on Rails, love a bit of Elixir / Phoenix and learning Rust.
I also poke through other people's code and make PRs for OpenSource Ruby projects that sometimes make it. Currently working for InPay who are based in Denmark...”
This year my main festive gift from the mighty Kat was a long awaited Raspberry Pi. Just never seemed to have the funds to nab one myself and I am pretty chuffed. If you’ve not heard of one then you’ve been living under a rock for the last year. The Raspberry Pi is basically just a very small, barebones computer. In fact its so minimal that it doesn’t even come with a case.
You can see on the board that the mounted interfaces are a dual USB port, micro-USB power supply, HDMI output to monitor, audio out, video out, GPIO pins.
You might have enough bits and bobs lurking in your cupboard full of cables and old hardware to get going but alas I do not. So in order to get started I need some way of hooking this up to a monitor, keyboard and powering the thing.
USB Keyboard
No PS2 ports so its all USB, so a USB Keyboard is needed. Relatively cheap, I’ve spotted a great wireless one with a touch pad for £25 but for now this one will do.
While the Raspberry Pi can be easily used with a modern television I can’t see myself sitting in the front room while I’m playing with it for the time being. You can use any monitor or television with an HDMI or DVI connection. So you’ll need a cable
My spare monitor is a VGA which won’t work without an adapter to convert the signal. £30 for an adapter is a bit much really. I’ve secured a DVI monitor from a friend for £10, so I’ve opted for the HDMI to DVI while I’m playing.
SD Card / Operating System
You’ll need an SD Card to install the operating system on. Fortunately we have an old 4Gb card from a Camera. So cost £0. Yay. average cost on Amazon about £6 so not bad.
Install it yourself
You can follow the tutorial on the Raspberry Pi Downloads page to copy an OS onto a card.
Pre-installed
You can get an 8Gb (and upwards) SD Card from ThePiHut with one of two distributions from £8.99.
Raspbian – pre-installed Raspian is an optimised version of Debian, containing LXDE, Midori, development tools and example source code for multimedia functions.
OpenElec / XBMC – pre-installed Open Embedded Linux Entertainment Center, or OpenELEC for short, is a small Linux distribution built from scratch as a platform to turn your computer into a complete XBMC media center.
That’s a start I’ve ordered what I need so now I have to sit and wait. I’ve got a few ideas about what I’d like to build.
MAME centre
Media centre
Spotify streaming straight into the HiFi
So I’ll do a bit of research and buy a book or two.
Resources
There’s plenty of resources out there as well as some physical publications to get started with.
Robs-iMac:testapp rl$ gem install therubyracer
Building native extensions. This could take a while… ERROR: Error installing therubyracer: ERROR: Failed to build gem native extension.
extconf.rb failed *
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers. Check the mkmf.log file for more
details. You may need configuration options.
Gem files will remain installed in /Users/rl/.rvm/gems/ruby-1.8.7-p370@thebevy/gems/libv8-3.3.10.4 for inspection.
Results logged to /Users/rl/.rvm/gems/ruby-1.8.7-p370@thebevy/gems/libv8-3.3.10.4/ext/libv8/gem_make.out
It seems that libv8 requires Gem to exist, however rubygems is not available by default in Ruby 1.8.7. Ruby 1.9.x it is.
Robs-iMac:thebevy rl$ RUBYOPT=-rrubygems gem install therubyracer
Building native extensions. This could take a while...
Fetching: therubyracer-0.10.2.gem (100%)
Building native extensions. This could take a while...
Successfully installed libv8-3.3.10.4
Successfully installed therubyracer-0.10.2
2 gems installed
Installing ri documentation for libv8-3.3.10.4...
Installing ri documentation for therubyracer-0.10.2...
Installing RDoc documentation for libv8-3.3.10.4...
Installing RDoc documentation for therubyracer-0.10.2...
I seem to use Apache less and less these days, so every year or so I have to try and remember the syntax for VirtualHost configs, redirects and the like.
When you’ve got lots of temporary files on a unix server and you never clean them out this might help. Remove files that were created more than 14 days ago like so…
“www.” for the most part is a pointless idea. We all know what a web page is. The “www.” prefix is outdated although necessary evil. I guess the same could be said of http:// and https:// for web requests …we all know what it means.
Here’s a quick snippet of my apache config to push all traffic from www.loathso.me to loathso.me
<VirtualHost *>
ServerName www.loathso.me
ServerAlias loathso.me
DocumentRoot /var/www/loathsome/current/public/
RackEnv production
RewriteEngine on
RewriteCond %{HTTP_HOST} ^www\.loathso\.me
RewriteRule ^/(.*)$ http://loathso.me/$1 [R=permanent,L]
CustomLog /var/log/apache2/loathsome-access.log common
ErrorLog /var/log/apache2/loathsome-error.log
</VirtualHost>
MySQL doesn’t have a built in type for an IP Address, PostgreSQL does though. You’ll find that ip addresses are often stored as an integer. You can translate between an integer and ip address and vice versa with a built in MySQL functions. In a recent piece of work we had to detect a user’s country code based on their incoming IP via against a range of IPs (stored as integers).
mysql> SELECT INET_ATON('192.168.0.1');
+--------------------------+
| INET_ATON('192.168.0.1') |
+--------------------------+
| 3232235521 |
+--------------------------+
1 row in set (0.00 sec)
mysql> SELECT INET_NTOA('3232235521');
+-------------------------+
| INET_NTOA('3232235521') |
+-------------------------+
| 192.168.0.1 |
+-------------------------+
1 row in set (0.00 sec)
Wouldn’t it be nice to get a Rails model to accept an ip address and store it as an integer. Well its basically serializing the ip address and using Rails 3.1’s new serialization api we can do the following.
class IpEncoder
#
# Converts IP to number
# inet_aton
#
def load(n)
return unless n
[n].pack("N").unpack("C*").join "."
end
#
# Converts number to IP
# inet_ntoa
#
def dump(n)
n.split(/\./).map(&:to_i).pack("C*").unpack("N").first
end
end
Basicially a class with two methods IpEncoder#load encodes its input, and IpEncoder#dump decodes it. Then you simply add the following to your model.
require 'ip_encoder'
class Log < ActiveRecord::Base
serialize :ip_address, IpEncoder.new
end
And there you have it.
Rob-Laceys-MacBook-Pro:loathsome roblacey$ ./script/rails c
Loading development environment (Rails 3.1.2)
>> Log.create(:ip_address => '192.168.0.1')
SQL (0.5ms) INSERT INTO "logs" ("ip_address") VALUES (?) [["ip_address", 3232235521]]
=> #<Log id: 1, ip_address: "192.168.0.1">
I was mulling at the end of last year that while I’ve been programming for far too many years now its been for the most part web development and databases. But I don’t know how to build a GUI, and least of all one that would be cross platform. Time to learn.
I’ve just picked myself up a copy of O’Reilly Java Swing 2nd Edition which, while its old, should help me get to grips with building my first GUIs.
As an interesting learning process I’ve decided that while of course this is all about Java that I am going to read the book in Java, I shall translate it all into JRuby since I use Ruby as my programming language of choice. So I’ll learn three skills in one;
GUI Development
Java
JRuby
I think the best way to pick it up is to go through every last example until it becomes second nature so all the Java AWT and Swing examples I come across in the book I shall be adding in a new jruby-swing github repository are here as JRuby.
