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Piers Cawley Practices Punditry

Work with us

If the last post about our Javascript issues didn’t put you off, then you might be interested to know that we’re hiring. If you’re an experienced, test infected Ruby on Rails programmer with some Javascript and a real world consumer website or two under your belt, and you’re happy to work in Newcastle upon Tyne, then we definitely want to hear from you. I’d probably be interested in at least hearing from you if you’re an experienced dynamic language programmer who has only recently made (or is considering making) the switch to Ruby and Rails. It’s only syntax after all.

The money’s decent, the work is interesting, the people (well, apart from me, obviously) are great, and Newcastle’s a fantastic city. Drop me a line, ping me on AIM/gTalk/Twitter or just send your CV to the jobs@amazing-media.com.

Published on Thu, 03 Jul 2008 06:00:00 GMT by Piers Cawley . Tags , , ,

Usability testing (throws) rocks

Usability testing is wonderful. But wow, its humiliating.

I’ve spent the last few weeks working on the Amazingtunes in page player. Amazingtunes is a music site, so we need to play music. However, we don’t like the way that most music sites work; either the music stops as you go from one page to another, or the player is a huge Flash app running in its own window. There has to be a better way. There needs to be a popup window if you want to eliminate stop/start behaviour, but there’s surely no reason not to keep the controls on the main page.

So, we set about writing somthing that did just that. We settled on using Jeroen Wijering’s excellent flvPlayer, which handles the media formats we need and has good Javascript control and communications. This sits in the child window and we use Javascript cross-window communication to have a player controller in the main window that looks something like:

Piers Cawley on amazingtunes.com
Uploaded with plasq’s Skitch!

This is all done in HTML and and Javascript, the progress bar does the Safari trick of running behind the tune data links, the buttons do their AJAX magic and the whole thing is rather slick, though I say so myself.

At least, we thought it was slick until we pointed the usertesting.com legions at it. Without exception, they ignore the in page player, foreground the popup and use the teeny weeny controls on the flash player. Originally, the popup window didn’t even display any transport controls, it just had a picture of some speakers and some text asking the user not to close it because it was playing the tunes. We added transport controls as a stopgap while we made the in page player work properly.

I sound like I’m whinging don’t I? It’s certainly a blow to the ego to see something we spent so much time and attention on being ignored by our sample users. On at least one occasion, while watching the screencasts I found myself boggling at the things the users did, and if I didn’t shout “Just play some bloody music!” at the screen, then I came worryingly close.

It would be easy to retreat into a state of denial: “They’re not our target users! They’re stupid! They’re American! If they would only magically intuit the way we think they should use the site!”. And maybe it would be comforting to do so, for a while. The right thing to do is to suck it up – take away from those videos the sure and certain knowledge that bits of the site don’t work and do something about it.

We may dislike the ‘popup window for transport controls’ model of controlling music playback, but users are cool with it. And it’s not as if the work we did on making the in page player work is going to be wasted – widget is straightforwardly event driven so it’ll work just as well in the popup window, and the communication protocol will be much simpler. Having the player in its own window means we’ll be able to extend its interface in ways that would be hard when the player had to share window space with the rest of the page. In the end, it’s all good.

But… damn that in page player was sweet. I learned Javascript as I wrote it (mostly by pretending it was Perl with odd syntas) and I’m bloody proud of it. I’ll happily replace it with the next iteration (which I’m already working on), but it’ll be with a pang of remorse all the same.

Published on Thu, 03 Jul 2008 04:55:00 GMT by Piers Cawley . Tags , , ,

Announcing Announcements for Ruby

I’ve just pushed a just about usable (but horribly untested) port of Vassili Bykov’s very lovely Smalltalk Announcements framework onto github. It’s a very raw port at the moment (the interface isn’t what you’d call idiomatic ruby yet), but I shall be working on that soon. Documentation (beyond a synopsis in the readme file) is nonexistent, but I reckon that there’s the core of something useful there (I’ve got plans for using it in Typo as the basis of a Wordpressesque plugin architecture and I need it for my Sooper Sekrit Project too…).

Expect some more details on the whats and whys in this blog soon, but if you want to have a play, you’ll find it at http://github.com/pdcawley/announcements. Enjoy.

Published on Sun, 29 Jun 2008 04:46:00 GMT by Piers Cawley . Tags

git is the monads

When, in the course of learning about Haskell, I reached the point where I thought I understood what Monads were for, I wrote about it. In the comments, Seth Gordon observed that:

There are two kinds of people who try to learn Haskell: the people who give up because they can’t figure out monads, and the people who go on to write tutorials on how to understand monads.

I remembered this today as yet another git tutorial rolled by in my newsreader. Maybe git is the monads of version control.

What other ‘monads’ are there out there? RESTful routing in Rails seems an obvious candidate, but I’m sure there’s more.

Published on Thu, 15 May 2008 01:57:00 GMT by Piers Cawley .

Rails tip: Dealing with out of sync migrations

Sometimes, for one embarrassing reason or another (usually involving chaotic branch merges…) a database migration can get leapfrogged. When this happens, it’s tempting to renumber the leapfrogged migration, but that breaks any servers where the migration didn’t get renumbered. Here’s how I dealt with it recently:

class MaybeOldMigration < ActiveRecord::Migration
def self.up
unless old_migration_applied?

def old_migration_applied?
# Checks that the schema looks as it should
# if the old migration got applied

Yeah, it’s a hack, but it’s a fairly robust hack.

Published on Wed, 07 May 2008 10:09:00 GMT by Piers Cawley .

A quick Javascript formatting tip

IE’s a pain. The particular pain I want to write about is its pickiness about Javascript object literals. Consider the following Javascript object:

{ success: function () {…},
failure: function () {…},

If you’re used to programming in Perl or Ruby, that trailing comma’s perfectly fine, in fact leaving it there is sometimes considered good practice because it makes it easy to extend the hash, just add a new row and leave another trailing comma.

The trouble is, it’s not strictly legal to do that in Javascript. Pretty much every implementation out there will allow it though.

Except IE.

So, I’ve taken a leaf out of Damian Conways Perl Best Practices and writing my object literals as:

{ success: function () {…}
, failure: function () {…}

By sticking the comma at the beginning of the line, I’m never going to make an object that breaks IE, and adding a new line to the hash is straightforward too. Just stick the cursor in front of the }, type my leading comma, space, attribute name, and hit return when I’m finished.

I’ve also started using the same practice pretty much everywhere else that I’ve got a comma separated list of things:

var foo
, bar
, baz
$.each( anArray
, function () { … }

It looks weird at first, but trust me, it grows on you.


In the comments, I make reference to tweaking Steve Yegge’s excellent js2-mode to handle leading comma style a little more gracefully. Since then, I’ve made it work and attached a diff to this issue on the project’s issue tracker.

Published on Wed, 16 Apr 2008 04:01:00 GMT by Piers Cawley under . Tags , ,

Ads are gone

Back when I was writing the occasional “How do you find me?” article, I would get some weird ads showing up. On one occasion, I commented that the searcher had obviously just typed a homework question into google and expected an answer. All the ads on that page ended up being for sites that would write your essays for you.

“Hmm…” I thought, “That’s not good.”, and set about adding those advertisers to the block list.

Then, in another article, I ranted about those, ah, bastions of democracy (thank you, Tom Lehrer) who indulge in comment spamming and found myself advertising them.

Rolling back the enlightenment which discussed, amongst other things, my Uncles’ marriage after 36 years together (yay!) attracted some pretty dodgy ads too.

To my shame, none of these made me rethink the advertising, I just extended the filter and shook my head at the unpleasantness of it all.

The straw that broke the camel’s back was the advertising around Fat is an economic issue ran utterly counter to the spirit of the of the article, and they were like “whack a mole”. Every time I extended the filter, another ad for another bloody health insurance leech or some other snake oil peddler popped up.

So, screw that, the Google ads are gone – it’s not as if they were making me a huge amount anyway. I’ll continue with the left margin Amazon links though – nobody ever buys anything I recommend, but I like the pictures.

Published on Tue, 15 Apr 2008 01:33:00 GMT by Piers Cawley .

Fat is an economic issue

Terry Pratchett once observed that a character of his was anorexic because every time they looked in a mirror, they saw a fat person. By that measure, I’m anorexic, though I tend to avoid mirrors. By more objective measures, I’m morbidly obese – 6’ tall, 346 pounds; the Body Mass Index calculation is never going to give a good number.

To listen to some sections of the press, I might as well be public enemy number one. A drain on the public purse, a morally bankrupt insult to the eye of the right thinking, Daily Mail reading healthy public. Apparently, I have the self control of an incontinent puppy and spend my time sat on my arse in front of the TV or looking at child porn on the internet, constantly stuffing my face with lard and chocolate.

Mmm… lard and chocolate…

Now, everyone’s entitled to their opinions of the morality of others. Catch me on another day, and I can rant for ages about the ugliness of the way diet and beauty industries stoke insecurities to sell product. Today I want to talk about the cost issue.

Fat people aren’t cheap to keep – we tend to die younger, and in the process of our dying we cost a lot of money. But dying can be an expensive business and however we go, we all do sooner or later. Fat people’s healthcare costs may well be higher than those of healthy people of the same age, but those healthy people could end up waiting ‘til they are 80 before dying of something horribly expensive like cancer, or Alzheimer’s.

When you add up the net lifetime healthcare costs of the average healthy person, and those of the average obese person, the healthy person costs more.

This is analogous to the “Long Tail” idea – the idea that the long tail of low sales of ‘specialist’ books/records/services adds up to being of greater value than the total sales of the top 100 or whatever. Obvious when you think about it, but running counter to traditional thinking in this area.

We’re really good at spotting the big things, but rather less good at spotting the slow accretion of small things. Each drop of water that falls from a stalactite to a stalagmite doesn’t appear to contribute anything. Nevertheless, the stalactite and stalagmite got there somehow.

I find this knowledge rather heartening. Okay, so as a fat git with diabetes, I’m likely to die young, but that’s my business. The pernicious idea that the broader population of tax payers is somehow suffering because of me and that because of that I should be denied access to health care isn’t just morally repugnant, it’s economically illiterate.


Lifetime Medical Costs of Obesity: Prevention No Cure for Increasing Health Expenditure from PLoS medicine. The paper describes a mathematical model rather than something which does the arithmetic on a real population, so it’s only as good as the assumptions, but it does seem compelling that the driver for high total healthcare costs over a lifetime is the length of that life. But, as I fat git, I might be expected to say that. Ho hum.

Published on Sat, 12 Apr 2008 01:41:00 GMT by Piers Cawley under . Tags ,

Code is data, and it always has been

I’m just back from the first Scotland on Rails conference, and a jolly fine conference it was too. Much kudos is due to Alan, Graeme, Abdel and Paul. It was hard to believe that this was the first conference these guys have run and I think all my fellow delegates hope it won’t be the last. As I said in the Pub on Saturday night, I’d had a talk proposal knocked back and, in that situation, it’s terribly easy to find yourself sitting in a session thinking “Bloody hell, my talk would have been better than this!”, but not at this conference.

A phrase that cropped up a couple of times was the old saw that “Data == Code” – it’s very hard to avoid the idea once you start talking about code generation or Domain Specific Pidgins, parsing… I first came across the idea in The Structure And Interpretation of Computer Programs where it’s elegantly phrased as “Data is just dumb code, and code is just smart data”. Traditionally, the idea seems to be attributed to John McCarthy, the inventor of Lisp. But it’s older than that. Way older than that. The idea is actually older than Computer Science. It lies at the core of Turing’s original paper On Computable Numbers, with an Application to the Entscheidungsproblem in which invents computer science on the way to proving that it’s impossible to decide algorithmically whether a given statement of arithmetic is true or false.

In the course of the paper, Turing posits what has become known as the Halting Problem:

Given a description of a program and a finite input, decide whether the program finishes running or will run forever, given that input.

Turing’s proof runs something like this:

Suppose we have a subroutine halts?(code,data) which solves the halting problem. Let’s use that to write something like:

def counter_example(code)
if halts? code, code
for (;;)


and ask the question “What happens when we run counter_example.rb < counter_example.rb”? If halts? reckons that counter_example would halt, given itself as input, then counter example will enter an infinite loop, but if halts? reckon that it would enter an infinite loop, then it would halt. Which is a contradiction. Which means that there can be no subroutine halts?, which means that maths is hard enough to be interesting and occasionally undecidable.

Look at how the proof works – it’s built around the idea that code can be treated as data. In fact, you could say that the Turing Machine looks like it does because Turing was working backwards from this core idea to describe a sufficiently powerful machine that could obviously treat it’s own description as data. Certainly when you compare the clarity of his proof that the halting problem is undecidable (given the idea of the universal Turing machine) with the contortions required to make mathematics swallow its own tail in similar fashion so that Gödel could prove his Incompleteness Theorem.

So, if you want to know who the idea that code is data is due to, the answer (as is so often the case in our field) is Turing.


Incidentally, Turing is also responsible for the first ever bug – his original implementation of a Universal Turing Machine has a couple, one of which is probably a dumb typo (which even I could spot when I read the paper). Another is more subtle, but still fixable. Somewhat delightfully, a young grad student, (Donald W Davies, who invented packet switching) spotted these bugs and told Turing:

I … found a number of quite bad programming errors, in effect, in the specification of the machine that he had written down, and I had worked out how to overcome these. I went along to tell him and I was rather cock-a-hoop … I thought he would say ‘Oh fine, I’ll send along an addendum. But in fact he was very annoyed, and pointed out furiously that really it didn’t matter, the thing was right in principle, and altogether I found him extremely touchy on this subject.

Nearly fifty years later Davies wrote and published a debugged version of the code, which you can find in The Essential Turing. One lesson to draw from the above is that getting annoyed at people pointing out trivial bugs in example code is also at least as old as computer science. Rather splendidly, there’s also a story of the chap who wrote the first ever assembler getting a serious telling off from Turing because the computer’s time was too valuable to waste it on converting symbols into machine code when humans were perfectly capable of doing it themselves. Who knows, maybe Turing’s contention was actually true back in the days of the Manchester Baby…

Published on Mon, 07 Apr 2008 00:12:00 GMT by Piers Cawley under , . Tags , , ,

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