ACCU World of Code

is an excellent book by Tristan Gooley (isbn 978-1-473-61522-9). As usual I’m going to quote from a few pages: One of the universal truths of human observation is that we see more of what we expect to see and less of what we don’t expect to see…

is an excellent book by Niels Pflaeging (isbn 978-0-9915376-0-0). As usual I’m going to quote from a few pages: What Taylor pioneered was the idea of consistently dividing an organization between thinking people (managers) and executing people (w…

is an excellent book by Niels Pflaeging (isbn 978-0-9915376-0-0). As usual I’m going to quote from a few pages: What Taylor pioneered was the idea of consistently dividing an organization between thinking people (managers) and executing people (w…

My OpenMarket colleagues and I ran a workshop at TECH(K)NOW Day on how to write your own programming language: A big thank you to my colleagues from OpenMarket who volunteered to help: Rowan, Jenny, Zach, James and Elliot. An extra thank you to Zach …

Today I found I could not connect out through my proxy server with FileZilla It stopped working when I changed my password to something containing a double quote “. The solution? Change to use WinSCP.

I have been working on a prototype level editor for Rabbit Escape, and I’ve had trouble getting the layout I wanted: a toolbar at the side or top of the screen, and the rest a zoomable workspace. Something like this is very common in many desktop appli…

Today I was trying to make a simple tarball of a project + its dependent jar using the maven-assembly-plugin. I know this is a terrible way to do anything, but hey, just in case someone else wants to do something just as terrible, here are my pom.xml a…

I used to run Planet Code using Venus but that started breaking recently with 500 errors for SNI-enabled sites, and it looks very unmaintained. I considered some other static aggregators, but on shared hosting it’s hard to get the right Ruby version an…

is an excellent book by Miyamoto Musashi, translated by Thomas Cleary (isbn 1-57062-748-7). As usual I’m going to quote from a few pages: Preface: In common parlance, to do something with a real sword means to do it with utmost earnestness… The Bo…

is an excellent book by Miyamoto Musashi, translated by Thomas Cleary (isbn 1-57062-748-7). As usual I’m going to quote from a few pages: Preface: In common parlance, to do something with a real sword means to do it with utmost earnestness… The Bo…

If you want “tomorrow” in Python datetimes, don’t construct a datetime like this: from datetime import datetime, timedelta td = datetime.today() tm1 = datetime(td.year, td.month, td.day + 1, 14, 0, 0) # Don’t do this! Because it will work sometimes, b…

cyber-dojo now supports practising jQuery. Enjoy 🙂

cyber-dojo now supports practising jQuery. Enjoy 🙂

I have sent the following letter to LTS.Team AT oxfordshire.gov.uk in response to https://consultations.oxfordshire.gov.uk/consult.ti/OxfordRiversideRoutes/. &nbsp Hi, &nbsp I have submitted the following via the questionnaire: &nbsp The Oxpe…

I have sent the following letter to LTS.Team AT oxfordshire.gov.uk in response to https://consultations.oxfordshire.gov.uk/consult.ti/OxfordRiversideRoutes/. &nbsp Hi, &nbsp I have submitted the following via the questionnaire: &nbsp The Oxpe…

Today at the Egham Raspberry Pi Jam we did two things: 1. The Broken Levels Challenge Some nasty person came and broke our levels for our game Rabbit Escape and we need you to fix them! To play this game you will need a PC version of Rabbit Escape, ou…

C has a facility for checking dynamic assertions at run-time. It’s inside <assert.h> and its called assert. Now assert is a macro, so why isn’t it called ASSERT? I don’t know. Prior art no doubt. Anyway, assert is a dynamic runtime feature, you can only use it inside functions. /* not inside a function, won’t…

C has a facility for checking dynamic assertions at run-time. It’s inside <assert.h> and its called assert. Now assert is a macro, so why isn’t it called ASSERT? I don’t know. Prior art no doubt. Anyway, assert is a dynamic runtime feature, you can only use it inside functions. /* not inside a function, won’t…

Events are locked? Exist on stack or heap? Can cause garbage collection? Meaning of this? Always has a default constructor? Default construction triggers static construction? Can be null? Use with the as operator? Can be locked? Can have a destructor? Default field layout? Can be a volatile field? Can have synchronized methods? Can be pointed…

Events are locked? Exist on stack or heap? Can cause garbage collection? Meaning of this? Always has a default constructor? Default construction triggers static construction? Can be null? Use with the as operator? Can be locked? Can have a destructor? Default field layout? Can be a volatile field? Can have synchronized methods? Can be pointed…

HikingMaps is now also available in the Tizen Store for Tizen 3.

HikingMaps is now also available in the Tizen Store for Tizen 3.

On Wednesday 28th June 2017 a group of people from OpenMarket went to the Fora office space in Clerkenwell, London to run a workshop with the Women Who Code group, who work to help women achieve their career goals. OpenMarket provided the workshop “Wri…

More than twelve years ago Tim Joyce passed on some programming wisdom: With programs tell don’t ask, vice versa for people. This was a bit abstract for me at the time but last night it came back to me as what is wrong with the code I am currently …

More than twelve years ago Tim Joyce passed on some programming wisdom: With programs tell don’t ask, vice versa for people. This was a bit abstract for me at the time but last night it came back to me as what is wrong with the code I am currently …

For my attempt to improve the asyncio.as_completed Python standard library function I needed to build a local copy of cpython (the Python interpreter). To test it, I needed the aiohttp module, which is not part of the standard library, so the easiest w…

Series: asyncio basics, large numbers in parallel, parallel HTTP requests, adding to stdlib In the previous post I demonstrated how the limited_as_completed method allows us to run a very large number of tasks using concurrency, but limiting the number…

For when git status is not enough, I wrote git what: If you often have a few branches on the go, it could be useful.

Series: asyncio basics, large numbers in parallel, parallel HTTP requests, adding to stdlib Update: slides of a talk I gave at the London Python Meetup on this: Talk slides: Making 100 million HTTP requests with Python aiohttp. Update: see how Cristian…

By default, when you make a UTC date from a Unix timestamp in Python and print it in ISO format, it has no time zone: $ python3 >>> from datetime import datetime >>> datetime.utcfromtimestamp(1496998804).isoformat() ‘2017-06-09T09:00:…

Went for a walk from Berkhamsted to Tring, see GPS data and some pictures: here, here and here.

Went for a walk from Berkhamsted to Tring, see GPS data and some pictures: here, here and here.

Been to Galloway for a few days of (wild) camping (around Loch Dee, Loch Trool, Merrick, Loch Finlas, Loch Doon). Also stopped in Carlisle before returning back to London. See my digital photo album for a few pictures.

Been to Galloway for a few days of (wild) camping (around Loch Dee, Loch Trool, Merrick, Loch Finlas, Loch Doon). Also stopped in Carlisle before returning back to London. See my digital photo album for a few pictures.

Series: asyncio basics, large numbers in parallel, parallel HTTP requests, adding to stdlib I am interested in running large numbers of tasks in parallel, so I need something like asyncio.as_completed, but taking an iterable instead of a list, and with…

Series: asyncio basics, large numbers in parallel, parallel HTTP requests, adding to stdlib Update: see the Python Async Basics video on this topic. Python 3’s asyncio module and the async and await keywords combine to allow us to do cooperative concur…

Went for a walk in the Cotswolds from Kingham to Moreton-in-Marsh, see GPS data and some pictures: part 1, part 2, part 3, part 4, and part 5.

Went for a walk in the Cotswolds from Kingham to Moreton-in-Marsh, see GPS data and some pictures: part 1, part 2, part 3, part 4, and part 5.

Series: Iterator, Iterator Wrapper, Non-1-1 Wrapper Sometimes we want to write an iterator that consumes items from some underlying iterator but produces its own items slower than the items it consumes, like this: ColonSep items(“aa:foo::x”); // Prints…

My talk from ACCU Conference 2017 where I describe a tiny programming language I wrote: Slides: How to write a programming language Cell source code: github.com/andybalaam/cell

Series: Iterator, Iterator Wrapper, Non-1-1 Wrapper If you want to wrap an iterable range with another that transforms the underlying iterators in some way and allows looping or constructing other objects: for (auto ch : Upper(“abcdef”)) { // Print…

Series: Iterator, Iterator Wrapper, Non-1-1 Wrapper To make your own iterable range in C++ that you can loop over or make a vector out of (mine is called Numbers): // Prints: // 3,4, for (auto n : Numbers(3, 5)) { std::cout << n << “,”;…

By default, Gradle does not show you what happened when a unit test failed: $ ./gradlew test … MyTest > Black_is_white FAILED org.junit.ComparisonFailure at MyTest.java:6 ^^^ WHAT ACTUALLY FAILED???? … This is insane, and can be fixed (t…

The ACCU conference is one of the highlights of my year. I ran a brand new session, a C++ Pub Quiz with an emphasis on fun and interaction, based loosely on the popular UK TV game show Countdown. In the TV version, contestants play individually …

The ACCU conference is one of the highlights of my year. I ran a brand new session, a C++ Pub Quiz with an emphasis on fun and interaction, based loosely on the popular UK TV game show Countdown. In the TV version, contestants play individually …

I maintain an unofficial aggregator of blogs by people who are involved with ACCU and things they might be interested in. It’s called Planet Code. Today I made it look slightly less ugly, and added several new blogs after attending the excellent ACCU C…

For a lightning talk at the ACCU Conference I wrote a little story: A story about magic and how we treat each other It describes one person’s journey towards realising that we need to act to be kind to each other, and not to expect it to happen automat…

is an excellent book by Jeff Nickoloff. As usual I’m going to quote from a few pages. The docker stop command tells the program with PID #1 in the container to halt. Like most Docker isolation features, you can optionally create containers …

is an excellent book by Jeff Nickoloff. As usual I’m going to quote from a few pages. The docker stop command tells the program with PID #1 in the container to halt. Like most Docker isolation features, you can optionally create containers …

is an excellent book by Herman Hesse. As usual I’m going to quote from a few pages. He learned more from the river than Vasudeva could teach him. He learned from it continually. Above all, he learned from it how to listen, to listen with a st…

is an excellent book by Herman Hesse. As usual I’m going to quote from a few pages. He learned more from the river than Vasudeva could teach him. He learned from it continually. Above all, he learned from it how to listen, to listen with a st…

is an excellent book by Peter Wohlleben (isbn 1771642483). As usual I’m going to quote from a few pages. In forked trees, at a certain point, two main shoots form, they continue to grow alongside each other. Each side of the fork creates it…

is an excellent book by Peter Wohlleben (isbn 1771642483). As usual I’m going to quote from a few pages. In forked trees, at a certain point, two main shoots form, they continue to grow alongside each other. Each side of the fork creates it…

According to a 2010 WHO-backed study the cost of safe water for every human would be about 10 billion US dollars per year. The UK government revenue for 2010-2011 was about 639 billion US dollars. I would vote for a political party proposing to raise …

If you’re trying to write a standard command-line tool in Java you are going to experience pain. In Python, if we want to do something with each line on input to your program, we can do something like: import sys for ln in sys.stdin: print(ln) # (…

is an excellent book by Gene Kim, Jez Humble, Patrick Debois, and John Willis (isbn 978-1-942788-00-3). As usual I’m going to quote from a few pages. Make infrastructure easier to rebuild than to repair. The average age of a Netflix AWS ins…

is an excellent book by Gene Kim, Jez Humble, Patrick Debois, and John Willis (isbn 978-1-942788-00-3). As usual I’m going to quote from a few pages. Make infrastructure easier to rebuild than to repair. The average age of a Netflix AWS ins…

Raspberry Pi 1 + battery pack + Bluetooth USB dongle + i-racer bluetooth car + Raspberry Pi camera + some Python code + loads of sellotape = Chaos car! Here’s the code: #!/usr/bin/env python2 import os import random import bluetooth import sys import…

It was my pleasure to run a small workshop style session at the excellent NDC-London conference. I ran a fun C++ game which parodies the popular UK TV gameshow Countdown. In the TV version contestants take turns picking 9 random vowels/consonants…

It was my pleasure to run a small workshop style session at the excellent NDC-London conference. I ran a fun C++ game which parodies the popular UK TV gameshow Countdown. In the TV version contestants take turns picking 9 random vowels/consonants…

I recently fought the Android emulator a lot to get my UI tests to run automatically during the build of Rabbit Escape, so I thought I’d better write down what I did before I forget. I already have tests that drive the Android UI (see e.g. SmokeTest.ja…

Here’s what I needed to get a dev environment for F-Droid up and running on Ubuntu 16.10, using F-Droid server version 0.7.0 (commit id 8147f9235), so that I could submit a package for inclusion in the F-Droid repository. Doing this is apparently the b…

I have been introducing some year 6 (UK) teachers to coding by showing them how to lay out a simple web page by writing HTML. I promised I would find some links to resources for them, so here it is: HTML and JavaScript My examples of how to write HTML …

Today I have spent hours trying to get wrangle Maven into letting me set up a sane Java project. The hardest parts were enforcing warnings-as-errors, and getting Maven to shut up a bit. Some code that warns My first problem was writing some Java code t…

At the excellent Agile on the Beach conference in Cornwall I did a presentation outlining some of the history, design and implementation of cyber-dojo. The video has just gone live on youtube.

At the excellent Agile on the Beach conference in Cornwall I did a presentation outlining some of the history, design and implementation of cyber-dojo. The video has just gone live on youtube.

Series: Snake in Elm, Elm makes me happy, Elm Basics, Elm Unit Test, Elm JSON I’ve been having fun with Elm programming recently. Elm is a replacement for JavaScript that is pure functional and highly practical. Here’s how to go from nothing installed …

Series: Lexer, Parser, Evaluator. Finally, we get onto the actual magic of the little language I wrote (Cell) – the evaluator, which takes in syntax trees and finds their real value, in the context of the “environment”: the symbols that are defined aro…

To start a programming project, we need to be able to build, format code, and run unit tests. Here’s what I have found makes a sensible starting point for a Haskell project. Full code: hunit-example. To build and run tests, just do:make setup make test…

Series: Lexer, Parser, Evaluator My little programming language, Cell (Cell Elementary Learning Language) is designed to be simple. I want to use it to explain how to write a programming language. The parser is only 81 lines long, so hopefully it’s not…

I am learning about Elm and web apps by writing a little game called sootl. It’s all SVGs animated with requestAnimationFrame(), and you control your player by clicking or touch the screen. Everything seemed good on desktop browsers, but on mobile it t…

Series: Lexer, Parser, Evaluator I wrote a little programming language, Cell which is supposed to be simple enough to help explain how a programming language works. Here’s the explanation of the lexer, which is the first part of a compiler or interpret…

I feel the title of this post over-promises, since I was not able to make an example that seemed simple to me. Anyway, here is a near-minimal example of how to use Netty to make a server that shouts back at you whatever you say: NettyExample.java:impor…

I am toying with writing an SVG-based game in (exciting-looking JavaScript-replacement) Elm, and I wanted an SVG that filled the whole screen and resized when the screen resized. I found it harder than I expected, so here is what I came up with for you…

In Java and several other languages, identifiers (e.g. method names) are allowed to contain unicode characters. Unfortunately, some combinations of unicode characters are logically identical. For example, á (one character: Latin Small Letter a with Ac…

I normally have several Firefox profiles open, and when I log out without closing the Firefox windows I get the “session restore” dialog on my next login. This is because of Bug 336193 which says that Firefox should shut down gracefully when it receive…

Series: Groovy, Ruby, BASIC, Dart, Elm, Python3+Qt5 I’m writing the game Snake in lots of programming languages, for fun, and to try out new languages. Python 3 broke compatibility to fix some mistakes – was it worth it? Qt 5 continues to offer more an…

In late April we exhibited at the ACCU Conference (#accuconf), which in many ways is our conference home. The first time we went was all the way back in 2007, and believe it or not we’ve not missed a single year since then. The conference is a great ev…

In late April we exhibited at the ACCU Conference (#accuconf), which in many ways is our conference home. The first time we went was all the way back in 2007, and believe it or not we’ve not missed a single year since then. The conference is a great ev…

Update: my ideas have changed quite a bit since I recorded this, especially about the idea that “every crime requires a punishment”. If you’d like to explore more, try this sermon by my friend Jörg. As a Christian myself I thought it might be interest…