I wrote my first open source ruby gem today. It's a pretty simple idea - supply a Gemfile or Gemspec and the gem tries to determine which license each included library falls under, and thus whether you have any requirements you must abide by with your own project. Here's an example output:

>> deriving_license ~/Code/rails_sample_app/Gemfile
Determining license for rails:
Trying from_gem_specification strategy...FAILED
Trying from_scraping_homepage strategy...SUCCESS
Determining license for adt:
Trying from_gem_specification strategy...FAILED
Trying from_scraping_homepage strategy...FAILED
Trying from_license_file strategy...CUSTOM
Determining license for app_constants:
Trying from_gem_specification strategy...FAILED
Trying from_scraping_homepage strategy...SUCCESS
Determining license for bcrypt-ruby:
Trying from_gem_specification strategy...FAILED
Trying from_scraping_homepage strategy...FAILED
Trying from_license_file strategy...CUSTOM

...
    
Detected 4 known licenses:
MIT: Expat License (14 instances)[http://directory.fsf.org/wiki/License:Expat]
Ruby: Ruby License (6 instances)[http://www.ruby-lang.org/en/about/license.txt]
BSD: FreeBSD Copyright (2 instances)[http://www.freebsd.org/copyright/freebsd-license.html]
GPL: GNU General Public License (2 instances)[http://en.wikipedia.org/wiki/GNU_General_Public_License]
The following dependencies have custom licenses: adt, bcrypt-ruby, bootstrap-sass, rack-protection, sqlite3

You can grab it from https://rubygems.org/gems/deriving_license or just by running 'gem install deriving_license'. Let me know if it's useful to you, and feel free to fix it up and submit a pull-request!

In an effort to add more content to this blog without having to stay up until midnight writing (see my last two verbose posts), I'm going to start adding my better Quora answers here too. This is one of my favourites!

When I was 12 and professed an interest in computers and programming, this was the advice my friendly neighbour offerred. Being 12, I can't remember if I had a clever retort to this line, but it certainly struck with me.

The neighbour in question was an engineering manager, running a large enterprise team delivering various aspects of online voting systems for government (amongst other things.) That Australia still does not have online voting available to most of the population probably goes some way to explain his view. (For what it's worth, it's now available in NSW to disabled voters who can't reach a poling booth as a trial run of the service, which has been in development for over a decade. It is a complicated system due to all the negatives ramifications of stuffing it up, but this is still a stupidly long time!)

As I grew up, studied engineering, then physics, then robotics, and then ultimately ended up working as a software engineer (not a programmer? Here's why...), I've thought back to this line more often than you'd expect for such a throwaway remark. But the question that really bugs me is; was the remark engendered by his management of a large team of varying talents on a long, complicated, and tedious project? Or is there actually some truth to it?

I've been reading Michael O. Church's latest blog series on the Macleod hierarchy of worker types in modern corporations lately, in addition to musing over my own role following a series of ennui and recruiter induced interviews. It's a great read (though lengthy!) and I agree with his analysis for the most part.

The short summary is that he's added a fourth class to Macleod's hierarchy (Losers, Clueless, and Sociopaths); the Technocrat. Losers (only in the sense that they realize corporate grunt work is a losing proposition) put in minimum effort for decent pay, and don't bother striving beyond this as their life is predominantly outside work. The Clueless believe that with dedication they'll be promoted into the upper echelons of the corporation, and take on more work for less reward than a rational approach would suggest. Sociopaths manipulate the system for their own ends rather than those of the corporation. They work hard only on projects likely to result in recognition or reward, and ignore, delegate, or sabotage work that doesn't.

Church's addition is the Technocrat, who operates like the Sociopath on the surface, but whose intent is to generate positive sum rewards for herself and the corporation. Where Losers are strategic, team-players, but not dedicated, the Clueless are dedicated team-players who lack strategy. The Sociopaths are dedicated strategists, but definitely not team-players. Technocrats are somewhat more pragmatic; they're strategic at all times, but only dedicated team-players when they sense their efforts will be positive sum and result in a better workplace for everyone. When this isn't the case, they bugger off somewhere else.

Humans being what they are, most people's first reading of this sees them side instantly with the good guy Technocrat, but I tried to analyse myself a bit more rationally. Bailing out of my robotics role because I didn't think it was teaching me enough or my efforts were improving the organisation may well have been characteristic of a Technocrat, but not enough for a strong classification (after all, a Sociopath would have done the same having realized the chances of promotion were negligible.)

I hope it's clear enough that I'm not Clueless. I'm incredibly lazy when I don't think something is worth doing, and I certainly won't due it just for the brownie points. I turned down a job offer only last week because the manager described the promotion prospects as being "Brilliant! After four or five years you'll have a really good chance of making team lead." (And Adrian, if you're reading this and thinking "I didn't say that?", that'd be because I actually turned down two jobs last week and I'm referring to the other one... #humblebrag)

I think I have some traits of the Loser, and not just my haircut. I generally work 9 to 5 only, and frequently take a pleasantly long lunch break. Whilst this is partly laziness, it's also that I'm well aware management is satisfied with my performance, and I don't see any reason to make them realize I'm capable of more effort or hours unless there's a kicker in it for me. I'm not a fan of delayed gratification, and don't fall for it when people suggest reward will come only after all the hard work is given. So this is strategic laziness then; lazy when the effort required to advance isn't justified by the reward offerred. I'm also not entirely referring to money either - recognition, interesting work, and an opportunity for learning are all alternative forms of persuading me to work harder. (And in my defence, I did stay late the last three nights because I had something interesting to work on!)

So, maybe I'm a Sociopath. Let's see now. I'm clearly strategic. I've clearly made several medium sized organisations think I'm a team-player. I've clearly bailed out on a great bunch of people because dedication to the organisation didn't pay. I've used a very positive sounding history of my startup failure to simultaneously leverage both title and salary inflation, and jumped straight into the most interesting chunk of available work in the organisation without having any experience of it. Seems pretty clear that if Church is wrong and there's no silver lining Technocrat class with which to paint myself, then I'm the number one contender for filling the office nerf guns with live ammunition.

Perhaps it's time to analyse my intent. Am I strategic, manipulative, and successful because I'm an asshole? Or is it because getting myself to the right position leaves me better able to deliver value to the organisation? That's certainly what I'd say in a salary review, but is that because I'm a cynical bastard with an affinity for telling people what they want to hear, or because I actually believe it? To answer this, I think we have to analyse the organisations I've worked in (which is a) simple, because there's only three, and b) fun, so just indulge me, ok?)

Academia (caveat - in Australia! This can be quite different in the USA.) is the home of a moderate number of satisfied Losers who love research for its intellectual freedom and accept the low salaries for this and a flexible lifestyle. There are numerous Clueless post-docs and joint-co-Chief Senior Principal Lecturers who for some strange reason never quite get that final title that'll give them stability and an excuse to slack off. Lording it above them all are the few Sociopaths who played the game well enough to grab tenure or switched tack into the bureaucratic arm instead. It's most definitely a rank culture and Technocrats are the strange bunch who've achieved exit velocity and left the gravitational pull of a satisfying Loser existence in the intellectual bubble of an otherwise parasitic and decaying organisation. Ouch.

My next role was in a fully industry funded research group within the same university, but the situation was unique enough that it can be thought of as an external consultancy simply renting space from the uni. That's certainly how it was sold to me, but proximity breeds homogeny, and the pull of the university hampered the success of what was otherwise a thriving self-executive culture with some guild aspects. Both the technical and academic staff had excellent mentoring from senior colleagues, the work was sufficiently interesting to breed dedication and a strong team spirit, and the pay and lifestyle flexibility were nothing to sneeze at. Its main downside was the division between academics and technical staff, both in monetary terms, and for interesting work and recognition. For a flat organisation with a surprising absence of Sociopaths at the top, it still managed to have a fair share of Clueless hoping for change that could never come. Fortunately it has a large number of happy and content Losers who've accepted the trade-off of increased comfort and interesting (if sometimes ignored) work, for a slower career progression and lower pay. There's a big part of me that wishes I could be happy in that position, but I can't.

Which brings me to my current employer, which for a startup is an absolutely canonical example of a tough culture frantically paddling back towards the guild from which it purports to have come, and truly wants to believe it can return. (Whether it can or not is a question for another day, and my thoughts on the matter have flipped a few times already in my short tenure here. Likewise whether it'll have a billion dollar exit or devolve into a semi-bankrupt zombie corporation. My odds are closer to 50/50 than I'd like, and I sometimes wonder if it's merely that e-commerce itself is growing so fast that's keeping us afloat.)

Without intending disrespect, most of my colleagues are Clueless (remember lads, this is a category label, not a derogatory term. You all know your memes better than any other group I've met). As is typical in many startups, they've been sold a dream, and blinded from any sharp realities by shiny toys and the 'culture club'. It also pays well, which the Clueless think is because they're irreplaceable and important, but in reality is because their output is important and probably a positive return on investment. Too few of my colleagues have considered that we're only recently profitable, and the number of business-destroying risks we face (mainly due to technical debt) is flabbergastingly high. Too many think that working hard and being seen to jump into the triage response when shit hits the fan will result in promotion and reward, without realizing that there isn't anywhere to be promoted to, our engineering spend is already too high to raise salaries any more, and fixing the fan mostly just covers you in crap.

There's a small number of Losers. For the most part, these people have been around the block a few times, recognise the high salary and low expectations available here, and happily meet them. They work hard only on the interesting problems (of which there are fortunately a decent number) and the most strategic of them have found their way into roles that avoid working with the legacy technical debt or too much triage. There are definitely a few strategic lurkers, waiting for more information on what the future holds, and who could morph into Clueless if they predict optimistically and incorrectly, or Sociopaths whatever the future as long as they predict correctly. (If it's a sinking ship, they'll bail. If it's a rocket ship, they'll find a path into upper management.)

There are Sociopaths scattered across the organisation, but due to its rapid growth, most have yet to reach upper management, and are effectively Sociopaths-in-waiting. Fortunately, there a number of truly positive-sum individuals who manage to be strategic (at least somewhat), team-players, and dedicated all in one. Their strategic efforts are aimed at projects that reduce technical debt, open up new areas of interesting work, and enhance the team itself. They don't always succeed, but it's clear that they're trying, and that they're not interested in playing politics like the Sociopaths are. It is largely due to these people that I'm still here.

And, it is because of these people that I think O'Church is right, and that Technocrats do exist. Which is lucky for me because otherwise I'd have to call myself a Sociopath, and I like to think I'm not quite that mercenary. If my trajectory looks like that of a Sociopath, I claim it's only because I haven't succeeded yet. I would love to be in a situation where I'm making my own life better at the same time as the corporation lots of money and a better place to be. I believe the best place for me to do this is in a guild culture, but in the absence of them in my field, in this city, at this point of time, I'm pretty happy in an organisation that's at least trying to be one.

So after a long and roundabout trip, I can now declare that I am actually a Technocrat. Relax. I'm not going to kill you after all.

These notes are mostly for my own reference, but will hopefully be useful to other people too.

Get homebrew:

• ruby -e "$(curl -fsSkL raw.github.com/mxcl/homebrew/go)" (this only works because Lion ships with a built in ruby)

Get ruby version manager (rvm) plus rails: 

• \curl -L https://get.rvm.io | bash -s stable --rails

Install gcc42 with which to build ruby (because XCode 4.2 now uses clang):

• brew update
  
• brew tap homebrew/dupes
  
• brew install autoconf automake apple-gcc42
  
• brew link --overwrite apple-gcc42 (you may or may not need this line, and should probably try without the --overwrite first)
  
• brew install libksba (some other library needed to by rvm to build ruby from homebrew sources)
  
• rvm pkg install openssl

Set rvm to use a recent ruby version by default:

• rvm use 1.9.3-p327 --default
• rvm alias create default ruby-1.9.3-p327
  

Install postgresql:

• brew install postgresql
• initdb /usr/local/var/postgres -E utf8

Get postgresql to start automatically login with:

• mkdir -p ~/Library/LaunchAgents
  
• cp /usr/local/Cellar/postgresql/9.1.5/homebrew.mxcl.postgresql.plist ~/Library/LaunchAgents/
  
• launchctl load -w ~/Library/LaunchAgents/homebrew.mxcl.postgresql.plist
  

Or start manually with:
  pg_ctl -D /usr/local/var/postgres -l /usr/local/var/postgres/server.log start
And stop with:
  pg_ctl -D /usr/local/var/postgres stop -s -m fast

This is a quick demo showing how you can use a $100 inertial measurement unit and a light weight laptop as a rough version of the Oculus Rift VR headset. A friend and I have a game idea we wish to build for the Rift but since units won't start coming until around December, and neither of us ordered one (since we didn't have the idea during the Kickstarter campaign), this is our "close enough" workaround.

Sample code for driving a Unity3D camera using an IMU is available on my GitHub page. [edit: 02/07/2013, now updated for the TinkerForge protocol 2.0]

Yesterday I finally received my inertial measurement unit (IMU). This is a tiny unit containing a gyroscope, accelerometer, and magnetometer. The gyroscope measures angular rotational velocities - how fast the unit is rotating around three axes. The accelerometer measures the accelerations along each axis - how fast the unit's speed is changing along each axis. The magnetometer measures the effect of prevailing magnetic fields on the unit - assuming the magnetic fields around the unit are non-changing, this provides a coarse measure of the unit's orientation.

All of this information is mashed together in a Kalman Filter (more specifically, Seb Madgwick's implementation of Rob Mahony's Direction Cosine Matrix (DCM) filter.) This filter integrates the gyroscopic information to determine orientation, and minimises error via feedback from the double-integration of the accelerations and the magnetometer information. This page at TinkerForge describes the IMU unit in detail, and the underlying equations can be found in Madgwick, S. O., An efficient orientation filter for inertial and inertial/magnetic sensor arrays, University of Bristol, April 2010. Overall, and especially considering it costs less than $100, this unit is awesome!

This particular IMU is actually built around a 32bit ARM processor, which does all the filter calculations onboard and processes USB commands to access the API. You simply run a daemon on your PC which translates TCP/IP commands to USB, and this then allows the manufacturer to have very simple APIs in a variety of languages, since they all just talk TCP/IP. Personally, I'm using Python because this project also makes heavy use of OpenCV which has Python bindings.

Ok, so what am I doing with it?

Well, first up, I stuck it to a laser projector. With tape.

Then I wrote some Python code to rotate and translate the image given the IMU's readings for orientation. In the image above, I'm taking my laptop's camera as the input image. I record a base orientation and then measure differences compared to this. The image gets rotated by the opposite of the change in roll. It gets moved left or right by the change in yaw, divided by the horizontal field of view angle, multiplied by the projector's horizontal number of pixels. Likewise, it's moved up or down by the change in pitch, divided by the vertical field of view angle, multiplied by the projector's vertical number of pixels.

For those readers who've not done IMU to sensor frame transformations before, this is one of the dodgiest hacks known to mankind. Despite this, it kinda sorta works.

This picture was awkward to take: My laptop is filming me. The projector is drawing the output on my wall. And I'm struggling to take the photo with my phone.

You know what - I'll just make a video... Stay tuned for part two! :-)