Author: Andy Balaam

I have been fiddling with some git-related shell scripts, and decided to try and follow the same approach as git in their structure. This means using the Unix system where each piece of functionality is a separate script (or executable) that communicat…

Posts in this series: Syntax, Deployment, Metaprogramming, Ownership There is often a trade-off between programming language features and how fast (and predictably) the programs run. From web sites that serve millions of visitors to programs running on…

Series: Why git?, Basics, Branches, Merging, Remotes Git is a very powerful tool, but somewhat intimidating at first. I will be making some videos working through how to use it step by step. First, we look at how to track your own code on your own comp…

When I launch gnome-mplayer to play back radio over my TV card (DVB), it asks me whether I want to resume from where I left off, which doesn’t make sense for this kind of stream. I couldn’t find a way to switch this off, but a little hacking with gnome…

Today I attended two excellent talks by Bjarne Stroustrup at the ACCU Conference 2013. The first was an inspiring explanation of the recent C++11 standard, and the second, “C++14 Early thoughts” was an exciting description of some of the features that …

Some unit test frameworks provide methods (often called setUp and tearDown, or annotated with @Before and @After) that are called automatically before a unit test executes, and afterwards. This structure is presumably intended to avoid repetition of co…

Series: Why git?, Basics, Branches, Merging, Remotes Putting your code in git is fast, flexible and powerful. You can track versions on a single machine, or scale up to thousands of people working together, with sub-teams, reviews and cherry-picking of…

I am switching to LXDE, and enjoying it, but a few things require some manual config before it’s just how I like it. To control the sound volume with the volume buttons, the default LXDE config in ~/openbox/lxde-rc.xml contains an entry like this: <…

In the previous post we looked at how it is possible to write reasonable code in Ant, by writing small re-usable blocks of code. Of course, if you’re going to have any confidence in your build file you’re going to need to test it. Now we’ve learnt some…

If you’re starting a new Java project, I’d suggest suggest considering the many alternatives to Ant, including Gant, Gradle, SCons and, of course, Make. This post is about how to bend Ant to work like a programming language, so you can write good code …

I am working on the problem of writing Ant build files in a test-driven way. One thing I found myself needing was a “dry run” mode, like many Unix tools have. For example, make has the -n or –dry-run option, which shows what it would have done, but do…

Parts: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12. Writing your first ever computer program on the Raspberry Pi. Today, we finish! Our game is almost done. All we need to do now is let you play several times, and give you a score at the end. First, becaus…

Parts: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12. Writing your first ever computer program on the Raspberry Pi. We’ve nearly finished our game. Next on our list is to fix that bug where you can’t exit some of the time, and make our code a bit tidier in t…

Parts: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12. Writing your first ever computer program on the Raspberry Pi. We’re writing a really simple game – you have to press a key when you see green, and not press a key when you see red. I’ve been promising for…

Parts: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12. Writing your first ever computer program on the Raspberry Pi. We’re writing a really simple game – you have to press a key when you see green. This time we’re going to add lots of instructions on each pag…

Parts: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12. Writing your first ever computer program on the Raspberry Pi. We’re writing a really simple game – you have to press a key when you see green. Today we’re going to wait for a key press. If we get one, we’…

Parts: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12. Writing your first ever computer program on the Raspberry Pi. We’re going to write a game that tests your reactions – press a key when you see green, but don’t when you see red. Today we see some of what …

I am a total beginner on this topic, but here is what I have found so far. Please correct me, advise me etc. in the comments. A colleague has written a program based on OSGi, which is a framework for obfuscating everything “modular” software, which I t…

Parts: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12. Writing your first ever computer program on the Raspberry Pi. Today we wait, but better, while we show the ready screen we made last time. In the process we cover two of the most important things you need…

Parts: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12. Writing your first ever computer program on the Raspberry Pi. Today we will write some writing on that blank screen we made last time. But first, a couple of tricks (we are doing magic after all). We’re g…

Parts: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12. Writing your first ever computer program on the Raspberry Pi. Today we will get an actual window to appear, with nothing on it! Last time we wrote a magic spell describing the bare outline of what how our…

I have been choosing a license for my ficticious programming language, Pepper. One consideration is the complexity of the (combination of) license(s) used. Complexity may be related to length, so for your enjoyment, here are the lengths of some popular…

Parts: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12. Writing your first ever computer program on the Raspberry Pi. Today we will write the very basic outline of our game. When we’ve finished it won’t actually do anything. In fact, it won’t even run. Writing…

Parts: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12. Writing your first ever computer program on the Raspberry Pi. See Part 1 for how to get and set up the Pi. Today we will find out how to write a computer program, and how to run it. We’re going to write o…

Parts: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12. In this series I intend to guide you through writing your first ever computer program. We will write our own game on the Raspberry Pi, which is a cheap-as-chips computer designed for learning about comput…

Dojo’s DOH requires a web server to run tests in a browser. But never fear: $ cd ~/code/dojo $ ls docs dojo util $ python -m SimpleHTTPServer & $ xdg-open http://localhost:8000/util/doh/runner.html Note that you will see some test failures, beca…

Quick reference of things I discovered about how to use associative arrays in bash. Note: bash version 4 only. (See also Bash Arrays.) Basics $ declare -A MYMAP # Create an associative array $ MYMAP[foo]=bar # Put a value into an associative …

To run your own DOH-based unit tests on the command line using Rhino: NOTE: this is Dojo 1.7 and above. For 1.6, there was a whole other cryptic incantation. Project layout Imagine your code is somewhere different from dojo, and another library you use…

I did a talk at work about lambda functions (anonymous functions), and something possessed me to make a timeline of when they were introduced into various languages. Some languages were born with them, and some grew them later – in the latter case I gi…

Posts in this series: Syntax, Deployment, Metaprogramming, Ownership I’m going to use a word here – don’t stop reading: Metaprogramming. Does the language provide what you need to avoid repeating yourself? Repeating boilerplate code, algorithms and mos…

You can watch the Tail Call Optimisation in C++ lightning talk video, which I gave at the ACCU 2012 conference in April. You can also read the (clearer and more correct) writeup I did later: Tail Call Optimisation in C++ or the subsequent article publi…

Someone claimed that everyone who has a Raspberry Pi has done what I did with it: try it out then file it in a drawer marked “must play with later”. To try and debunk this claim, here are some cool projects I have seen. Update: I made some videos on ho…

Series: Feel the cool, Basics, Closures, Recursion, Quotation, Lambda, Macros. Continuing the series on Scheme, this video explains the ultimate alternative – when nothing else is flexible enough, we can create our own bits of lanugage using macros. …

Series: Feel the cool, Basics, Closures, Recursion, Quotation, Lambda, Macros. Continuing the series on Scheme, this video explains the lambda function, which allows you to define anonymous functions. It goes on to bend your mind with 2 examples of the…

You read it here first, but now you can have a paper version of “Tail Call Optimisation in C++”, published almost as-is, in Overload 109 the journal of ACCU.

Series: Feel the cool, Basics, Closures, Recursion, Quotation, Lambda, Macros. Continuing the series on Scheme, this video explains on of the most powerful and unfamiliar features of Scheme: quotation. Quoting allows us to talk about and manipulate cod…

Series: Feel the cool, Basics, Closures, Recursion, Quotation, Lambda, Macros. Continuing the series on Scheme, this video describes the way you write code in Scheme: recursion. Recursive functions can be pretty efficient in Scheme, if you structure th…

Series: Feel the cool, Basics, Closures, Recursion, Quotation, Lambda, Macros. Continuing the series on Scheme, this video describes an important feature of functions in Scheme: closures. Closures allow functions to carry their “environment” around wit…

Series: Feel the cool, Basics, Closures, Recursion, Quotation, Lambda, Macros. Continuing the series on Scheme, this video describes some of the things you will need to understand to be able to write real programs. I introduce pairs, lists, and navigat…

Series: Feel the cool, Basics, Closures, Recursion, Quotation, Lambda, Macros. Here’s me trying to persuade you to be interested in a 40-year-old programming language, called Scheme, which is a type of Lisp: Slides for Scheme 1: Feel the cool

This series: Lightning talk, Explanation, Performance, Generalisation. In previous posts I discussed the construction of some C++ that does the same job that the tail call optimisation does in some other languages. The example code given showed the cas…

I recorded some videos of my JavaScript WTFs presentations: You can get the JavaScript WTFs slides. Update: all six episodes: JavaScript WTFs 1 – The Global Object JavaScript WTFs 2 – Equality and Inequality JavaScript WTFs 3 – Syntax JavaScript WTFs…

Update: watch the video In this series on Scheme: Intro, Basics, Closures. Here’s a presentation I did recently, on Closures in the Scheme programming language. Closures are the way the environment in which a function was created hangs around with it a…

This series: Lightning talk, Explanation, Performance, Generalisation. After I wrote a version of tail-call optimised code in C++ I became interested in its performance relative to normal recursion. The tail call version can process arbitrarily large i…

This series: Lightning talk, Explanation, Performance, Generalisation. Some programming languages make recursive programming more practical by providing the tail call optimisation. For a tiny talk at the recent ACCU conference I looked at how we might …

This series: Lightning talk, Explanation, Performance, Generalisation. Update: watch the video Here’s the lightning talk I gave at the ACCU 2012 Conference: Tail Call Optimisation in C++ It’s about how you would generate C++ code that represents a recu…

Update: watch the video In this series on Scheme: Intro, Basics, Closures. Here’s a presentation I did recently, on the basics of the Scheme programming language. Scheme: pairs, lists and recursion

sudo aptitude install python-dateutil python -c “import dateutil.tz; import datetime; print datetime.datetime.now( dateutil.tz.tzlocal() ).tzname()”

Usually when the channel lineup changes, I just have to do this:$ scan /usr/share/dvb/dvb-t/uk-CrystalPalace > ~/.mplayer/channels.conf But this time it is failing with:>>> tune to: 505833000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_3_4:FEC_AUTO:…

Update: watch the video In this series on Scheme: Intro, Basics, Closures. Here’s a presentation I did recently, introducing the Scheme programming language (a dialect of Lisp). Scheme: feel the cool Metaprogramming is very powerful, but is usually so …

I recently did a presentation at work on “surprising” things you may encounter in JavaScript. I present it here for your delectation: JavaScript WTFs Sorting arrays was the one that wasted me the most time. Arrays in JavaScript are a neat hack on top o…

Posts in this series: Syntax, Deployment, Metaprogramming, Ownership The fancy word for what I’m talking about here is Deployment. How easy is it, once you’ve written your code, to get it running on someone else’s computer? What barriers are there to s…

I have recently agreed to take over development of the JSLint plugin for my favourite editor, jEdit. To start developing I decided to build jEdit and its plugins from source, which wasn’t as easy as I would have expected (thanks to deffbeff for some po…

In this series I will comment on what I like in some of the languages I use. I will cover things that I find convenient, things that might lead me to write correct code, things that tend to make my code more readable, and possibly other things that I j…

Thanks to rvdavid, the network on my new PC is now working, despite Ubuntu misrecognising it: How to Get Gigabit Speeds from RTL8111/8168B PCI Express Gigabit Ethernet controller on Ubuntu Linux. This is the kind of thing I had to do 10 years ago. I th…

A long time ago I mentioned I’d added some (opt-in) usage tracking for FreeGuide. Here are the latest stats. I think they’ve held up pretty well given how much I’ve neglected the project…

Last night my friend and I uploaded the first version of Baby Distraction, an Android app featuring charming cartoon animals, vibration and sounds. I helped almost exclusively in an advisory capacity, but still am inexplicably proud of the result: it’s…

The Linux remote desktop client rdesktop grabs all keyboard events by default, which is good, because it allows e.g. you to Alt-Tab between applications and Ctrl-Alt-Del as if you were in front of the remote machine. However, it is also bad because you…

For a long time I’ve customised GNOME to have a vertical task bar on the left and launcher buttons across the top. I’ve struggled with a long-standing bug with using a vertical panel, and I’ve sacrificed quite a lot of screen space to make enough room …

Ordinarily, my motivations for doing open source work are clear: peer recognition and the satisfaction of knowing people are using my work. However, I’ve been distracted from that stuff recently because of my desire to scratch my own itch, by re-writin…

I use rdesktop to connect to some Windows machines, and it works beautifully. I like to allow it to grab keyboard input so I can switch and close windows on my Windows desktop without fear of accidentally doing something to the rest of my Linux desktop…

Posts in this series: Lexer, Parser, Evaluator I’m still really enjoying writing my Scheme interpreter Subs, which can now succesfully run all the example code from SICP up to section 2.3.4. I’ve made the changes I mentioned I would in the Lexer articl…

In a healthy team performing a technical task, there will be a lot of questions. Those questions will sometimes be asked by those with less technical knowledge, but (in a healthy team) there will be plenty of questions going back the other way too. Que…

Posts in this series: Lexer, Parser, Evaluator Subs has reached version 1.3.4, which means that it can successfully run all the tests from chapter 1 of SICP. This is very exciting. Last time I explained a bit about the Lexer, which takes in a stream of…

Posts in this series: Lexer, Parser, Evaluator I have been having a lot of fun recently writing my Scheme interpreter Subs. I have never implemented a full programming language before, so I am learning fast (mostly through mistakes) and wanted to write…

Why would you write a Lisp interpreter? I find that question difficult to answer, but the joy of open source is that I don’t have to answer it. Subs is a Scheme interpreter written in C++, and growing out of the excitement I have felt while reading Str…

If you’re interested in dealing with large directed graphs of dependent objects and want some tips on how to process them in a way that scales in terms of memory usage, you may be interested in the article I wrote for Overload, which is a journal of th…

I recently upgraded 3 machines to Lucid. I don’t recommend it. Broken after upgrade 2 out of 3 machines did not boot after upgrade to Lucid. One, an upgrade from Hardy, crashed hard during the upgrade (the screen was frozen with a prompt about lmsensor…

I’ve made a new release of FreeGuide today, which contains minor bug fixes. I changed the stability rating on sourceforge to “Production/Stable” (previously it was “Alpha”). Maybe I should bump the version number next time to 1.0. Certainly all this 0….

There is a piece of ancient wisdom which states: Premature optimisation is the root of all evil This ancient wisdom is, like all ancient wisdom, correct. However. It appears to have been reinterpreted as essentially meaning: Don’t design for perform…

I have just changed to myopenid and can delegate to them from my own openid URL by following the instructions here: https://www.myopenid.com/help#own_domain. Google don’t appear to let you delegate to them (i.e. have your own url). I’m really glad I ch…

I’ve managed to get NNDB, my C++ data storage library which is almost, but not entirely unlike SQL, into a fit state for a release. You can create tables, set indices on columns, insert data, retrieve data using something like a SELECT, filter it using…

My latest project is called NNDB. I’ve worked with databases for quite a long time now, and for a while I’ve been thinking about how they work under the hood. I know very little about it, but I thought I could learn a bit by trying to implement somethi…

My original plan for Diffident, the side-by-side diff viewer and editor that works in a terminal, was to implement basic editing capabilities before making another release. Of course, that turned out to be quite ambitious. It involves essentially imple…

It turns out the scan command from the linuxtv-dvb-apps package (on Ubuntu Hardy Heron, anyway) isn’t writing the correct channels.conf, and this makes some channels not work for me, including CBeebies, CBBC Channel and CITV. The fix is to do as this p…

I often want to search the SGI C++ reference for a keyword. The best way I have found to jump straight to the page I want is to use Google’s “I’m Feeling Lucky” search limited to searching within sgi.com. You can create a Firefox keyword search to allo…

Note: I am in favour of patents on inventions. I believe the current software patents system has a number of flaws (in decreasing order of importance to me): They attempt to close off the use of knowledge rather than open it up. If we were not filing …

When you first hear about the Read-Eval-Print Loop you might well think “So what?” as I did. What’s so great about being able to type commands interactively? But the thing is that it creeps up on you. Everyone already knows programming is an interactiv…

I really like Beyond Compare, which is a proprietary diff program with all those little touches that make it a joy to use*. The way I write code at work generally involves a bit of hacking in jEdit, checking the code myself, and then reviewing the code…

I’ve written a little script to show a different random background in GNOME every day, by looking inside your Photos directory. It will rotate them to be the right way up, if you have exiftran installed. Get it here: Random Background.

I love this: C++ Multi-Dimensional Analog Literals. I quote: Have you ever felt that integer literals like “4” don’t convey the true size of the value they denote? If so, use an analog integer literal instead:unsigned int b = I———I; It goes on …

I have asked myself this question several times, so I thought it was about time I did a test and found an answer. If the user of your program can supply you with a list of regular expressions to match against some text, should you combine those express…

Finally the number of people in our family is prime again. Mum, baby, siblings etc. are all really well and enjoying ourselves.

Last week we had an extended discussion at work about how we were going to implement a specific feature. This discussion hijacked our entire Scrum sprint planning meeting (yes, I know, we should have time-boxed it). It was painful, but the guy who was …

For a long time now I’ve been bugged by GNOME Bug 86382. Recent versions of GNOME have featured a window list applet which behaves badly when situated on a vertical panel (which is where I like to have mine). Older versions were ok except the buttons w…

Of course, I am bound to get a bug report immediately I have posted this telling me my fix breaks everything, but for the moment I am chuffed that I found, tested, and fixed a genuinely difficult bug. I am particularly proud because I wrote an automate…

So let’s quietly forget FreeGuide 0.10.8, which basically didn’t work. I fixed the problem (which was some nasty threading thing) by making the initial “Choose Channels for XMLTV” call from the first time wizard not do the clever stuff of displaying er…

A few weeks ago my Nintendo Wii started not accepting any Wii disks (but was still fine for GameCube ones… interesting). It made a clicking noise for a bit and then declared “Bad Disk” or something like that. I need my Wii. I watch all my TV through …

Due in March. Very excited.

I am still working slowly on moving FreeGuide forward. Somehow it seems my itches for FreeGuide are all about making it less annoying for people who are trying it the first time. I guess this is motivated by my desire for world domination. Anyway, we a…

At work at the moment we are putting a lot of effort into making our program not crash. Sensible, eh? It’s crashing because a) it uses an enormous amount of memory and b) it tends to fragment your remaining memory. One of the characteristics of this pr…

Update: I should point out at the beginning that I love C++. Anything below which sounds bitter or critical is borne of a deep and growing love. C++ is a journey into worlds of beauty and strength. I assert that C++ is an expert language. What do I mea…

At work at the moment, as part of an initiative to get with the 21st century, we are waking up to testing our code. Thus, I am writing a lot of unit tests for old code, which can be soul-destroyingly repetitive and very pointless-feeling (even though r…

On the subject of distributed source code management, Dan Watkins has just informed me that the launchpad team have created a bazaar branch of FreeGuide’s code, so if you’re into that kind of thing, you can download the code from that instead of our ce…

Git is supposed to work when you upload your repository to an http server, but in reality, no-one except me seems to use it, and it’s nothing like as useful as having a proper repository that people can commit to etc. So, here it is: http://repo.or.cz/…

There was a weird bug in my last.fm support for GSSMP, where it would crash when run from the GNOME panel, but be fine when run from a terminal. After two bugs fixes from Charles Bailey, the problem seems to have gone away, so I’ve finally been able to…

I’ve decided to use lighttpd on my new machine (which was generously given to me and features a 700GB raid array). My main reason for choosing lighttpd was the FLV streaming plugin for it that will make my Wii TV viewing experience a lot better. (It wo…

Check out a release candidate here: http://freeguide-tv.sourceforge.net/rc/ . So far I’ve only uploaded an RPM, but hopefully there’ll be a Windows exe and some other packages soon. Update: Windows installer now uploaded too. Test it! It’s got better c…

I’ve finally released to the world the secret extra duckmaze levels. They’re contained in the 0.2 release, which is also faster, and doesn’t freeze time. (As far as I know.) It’s got 18 levels, and a level editor, which means you can make more. Do it….

Caution: numbers that feel prime may be divisible by 3. For example, 51 and 57. Conversely, numbers that feel divisible by 3 may be prime. For example, 61, 89 and 97. Nominations for least prime-feeling numbers that actually are prime: 89 and 101. Nomi…