Code should communicate intent

In a previous post I advocated the principle of designing for readability. One of the ways you can achieve a higher degree of readability in your code is making sure it clearly shows what it is supposed to do. If your code communicates intent, it will be much easier for others to grasp the general idea by glancing over it.

An example please

I have been meaning to write about this for a while, but I couldn’t think of a good example. That’s one of the problems you face when you want to illustrate something with code. You don’t want the example to be overly abstract by limiting it to Foo’s and Bar’s, but at the same time, you want it to be understandable without having to provide too much context.

When I received a ‘Nice answer’ badge earlier this week for an answer I posted on Stack Overflow 5 years ago, I stumbled on a great example I wrote myself. What a happy coincidence!

The person asking the question had a simple class that looked like this:

public class MyObject
    public int ObjectID { get; set; }
    public string Prop1 { get; set; }

The question was how you could remove duplicates from a list of MyObject instances. Two instances were considered to be a duplicate of each other if they had the same value for the ObjectID property.

The answer that got accepted as the correct one suggested this solution:

var distinctList = myList.GroupBy(x => x.ObjectID)
                         .Select(g => g.First())

What this does is it groups the list based on the ObjectID and creates a new list with first instance from every group. You probably have to read the entire code block before you realise what it is doing.

My solution was to let the MyObject class implement the IEquatable<T> interface so you can use LINQ’s built-in Distinct method.

public class MyObject : IEquatable<MyObject>
    public int ObjectID { get; set; }
    public string Prop1 { get; set; }

    public bool Equals(MyObject other)
        if (other == null) return false;
        else return this.ObjectID.Equals(other.ObjectID); 

    public override int GetHashCode()
        return this.ObjectID.GetHashCode();

Just by looking at this class you know that the ObjectID property defines the identity of the class’s instances and that it’s used when checking for equality. This can now be used by LINQ’s Distinct.

var myObjects = new List<MyObject>();
myObjects.Add(new MyObject { ObjectID = 1, Prop1 = "Something" });
myObjects.Add(new MyObject { ObjectID = 2, Prop1 = "Another thing" });
myObjects.Add(new MyObject { ObjectID = 3, Prop1 = "Yet another thing" });
myObjects.Add(new MyObject { ObjectID = 1, Prop1 = "Something" });

var distinctObjects = myObjects.Distinct();

Even though my solution requires more code, I believe it is a lot better because of the intents it communicates:

  1. When you look at the class you know how instances will be compared for equality;
  2. The use of Distinct clearly show that you want to remove duplicates.

Some pointers

There a quite a few ways you can make the intent of your code more obvious.

Good naming

Use clear and descriptive names. This counts for everything: classes, variables, properties, methods, functions, … Don’t try to come up with shorter names just to save a few keystrokes. Something like numberOfAttendees is longer but far more readable than attndCnt. Why do developers seem to have a tendency to leave out vowels? What’s up with that?

Split things up

If it’s hard to come up with a clear and descriptive name for a class, a function or a method, that might be a sign that you’re trying to do too much in that part of the code. When you split things up it will be easier to name them and if you give them good names people can get away with only reading the names and skipping the implementation.

/* Hard to read */
var myString = "The quick brown fox jumps over the lazy dog.";
var vwls = "aeiou";
var tmpList = new List<Char>();
foreach(var c in myString)
    if (!vwls.Contains(c))
var myString2 = new string(tempList.ToArray());

/* Easier to read */
var sentenceWithoutVowels = RemoveVowels("The quick brown fox jumps over the lazy dog.");

I know there are better ways to remove vowels from a string, but I wanted to show some bad code that’s way too long and confusing on purpose. Imagine the better implementation is inside RemoveVowels. You don’t really need to know how it’s implemented when glancing over code. You know that that function removes vowels and that’s more than enough at that point.

Use built-in features

If you’re trying to do something that’s built into the language, framework or library you’re using, don’t reinvent the wheel. Use built-in features not only for performance reasons, but for recognisability as well. If people reading your code are familiar with the language, framework or library they’ll have an easier time understanding your code if they see things they recognise and know.

Wrapping things up

Making sure your code communicates intent is one of the ways you can design for readability. Naming things is one of the key concepts and it can be surprisingly hard sometimes. Let’s end with a famous and relevant computer science joke.

There are only two hard things in computer science: naming things, cache invalidation and off-by-one errors.

The daily stand-up is not dead

The other day, Jan, one of my awesome colleagues, wrote an interesting blog post on his vision of daily stand-ups. While I agree with him for the most part, there are a few things I have a slightly different opinion about. I also think the way we do stand-ups in the team I’m in is worth sharing. I wanted to reply with a comment to Jan’s blog post, but because of the finite amount of keystrokes I have left, I thought a blog post would be better than a comment.

The same time each day

First off, the same time each day thing. Every team that starts doing stand-ups does so at a designated time. But not everybody starts at the same time, neither might they be at the same location. People that start early will have to do a context switch and thus most likely lose productivity (between you and me, they will). If you need to be present from a distant location, this can also have an impact on the productivity of the stand-up, even in 2016. Technology is a bitch.

Our development team (Jan is in the app team, which is a separate team) is split up into three subteams: Ministry of Code, Fellowship of Code and Cabinet of Code. Every subteam has its own separate stand-up and they start at the same time every day. The Cabinet starts at 9:50, the Fellowship at 10:00 and the Ministry starts at 10:10.

The big advantage of starting at the same time is predictability, which makes it easier if you want to be a silent observer at another team’s stand-up. If we at the Ministry are working on a feature that touches code that someone from another team has written in the past, that person can set a reminder and join our stand-up to see if there’s something they can assist with. Or, if I know that I’ll need to build on a feature currently in development at the Fellowship, I can join their stand-up to learn how things are going and what decisions are being made.

I don’t believe the context switch has a negative impact on productivity, exactly because we always start at the same time. This way you can schedule your work a bit around the stand-up. Besides, in an office where NERF darts are almost eligible for frequent-flyer air miles, you learn to recover quickly from context switches.

Development teams only

Another annoying thing, but not directly related to this, is what is sometimes defined as a team that does a stand-up. Some companies tend to have stand-ups for development teams only. I don’t really see the point if you are closely working together on projects. You should know what’s going on, at least I do. If you have no idea what the guy next to you is doing, you have other problems. Stand-ups should be done with all those involved in a project. Talking to each other about code related issues is easy, the problems usually occur because of unclear or changing requirements.

The number 1 reason to go down the development-team-only road usually is that we assume the business side of things does not have time to participate or that they don’t care.

The Ministry, Fellowship and Cabinet stand-ups are all developer-only stand-ups, although everyone is free to join as a silent observer. A stand-up is basically a mini-meeting. That’s why I like to handle stand-ups the way all meetings should be handled. Only people that actually need to be present should be present. There’s no reason to have project leads, business leads, marketing members, copy members, customer care members and operations members present in every stand-up. If you need the entire project team, that’s probably a sign the scope isn’t suited for a stand-up. Book a separate meeting with a predefined agenda and a fixed start and end time. This will give everyone involved time to prepare which will make things more efficient.

The way we do stand-ups

We started using a Kanban system in our development team a few months ago. After a few weeks we already started seeing benefits, which might be food for another blog post. Before we were using Kanban, our stand-ups were like Jan described them in his post: 15 people in a big circle and everyone got one minute to talk. Someone held up a timer so you could see your time ticking away. It even beeped at 30, 50, 55 and 60 seconds in. That really created some sort of pressure because when your minute was up, you had to stop talking, mid-sentence or not. As a result of the timer and the size of circle, you typically heard things like “Yesterday I worked on feature X, today they same”. Not really valuable information.

Use the board Luke

That all changed when we started using the Kanban system. The most important thing is our Kanban board. Everything starts from the board, even our stand-ups. Instead of talking about what we did yesterday and what we’re going to do today, we talk about the state of the board. We go over each column, start downstream and work our way upstream.

  • Any blockers in ‘To launch’? No? Good! Yes? How could we help Operations? Let’s go check after the stand-up.
  • Hmm, that ticket has beens stuck in ‘Testing’ for four days now. Let’s go check with QA after the stand-up to see what causing them problems.
  • Is ‘Ready for Testing’ full? Yes it is. Is there anything further upstream that could move there but can’t because the WIP limit is reached? Ok, no problem, we’ll take that up with QA as well.
  • Anything waiting for a code review? Ok, I’ll handle that one.

When we get to the ‘In progress’ column (which means ‘In progress’ from a development viewpoint) we briefly go over what everyone is working on, check if the estimated due date is still realistic and discuss blockers or issues. If there are blockers or other issues, we take them up with the relevant person after the stand-up.

Finally we also have a glance at the ‘Todo’ column to see if there’s anything that’s more urgent than what we’re working on now.

Being late for a stand-up or working remote

If you can’t make it to the stand-up, that’s not really an issue since everything you need to know is perfectly visible on the board. We don’t have fulltime remote workers, so we only need to cover for people working from home now and then. And, the same applies there, actually. The board tells you what you need to know and if necessary you can always give the rest of the team a short update on Slack.

Not including people from other teams

This isn’t causing us problems either because we know from the board and from our stand-up when to go to other project members. Besides that we also keep the project leads up to date in an informal way. That information ends up in more formal planning meetings and from there it trickles down to the relevant teams and/or team members. This isn’t perfect yet, but it seems to be working pretty OK for now.


I do agree with the general sentiment of Jan’s blog post, but using Kanban and changing our stand-up accordingly has really been an eye-opener for me and changed the way I think about stand-ups. Our stand-ups have decreased in time and increased in efficiency. That’s always a nice combination!

Oh, if you wan’t become a member of the Ministry, the Fellowship or the Cabinet, have a look at our jobs page. We’re always on the lookout for new talent!

Design for readability

Surprisingly enough, one of the hardest things to do when you’re writing code is to keep things simple. There are many causes why we often make code more complicated than it should be:

  • Reducing line count. Even when the “gain” is small we tend to focus on this. It’s hard to resist turning three lines of code into one line.
  • Trying to be clever. Why keep things simple if you can prove you understand lambdas, monads, recursion, reflection and parallelism? Your colleagues will be so impressed!
  • Frameworkitis. You can’t resist the urge to try out the latest JavaScript framework, even though what you’re doing is far to simple to justify the use of it.
  • Design pattern hypochondriasis. An unnecessary concern about missing out on design patterns. You think your code resembles something that’s covered by a certain a design pattern and start refactoring your code in order to shoehorn in the pattern.

I try to be conscious of this whenever I’m coding. When you’re writing “clever code”, the short term high it gives you, makes you forget about the long term consequences. Unnecessarily complex code that you haven’t written yourself is hard to grasp. I’ve often had a feeling that I got the general gist of it, but I felt like I was missing something deeper, on a fundamental level. Why is this code so complex? What am I missing here? I’ve even had that happen with code I had written myself only months before.

Code is read much more often than it is written. Design for readability.

Try to keep things simple when writing code. That doesn’t mean you don’t have to think about what you’re writing though! Like I said, writing simple code isn’t always easier than writing complex code. When you keep things simple it will usually save you time when writing it, but not always. What is almost guaranteed, is that it will save everyone who has to read your code (including the future you!) a lot of time. So even if it would take you longer, it’s an investment well worth the effort.

Mocking properties in Python

It doesn’t happen all that often, but sometimes when writing unit tests you want to mock a property and specify a return value. The mock library provides a PropertyMock for that, but using it probably doesn’t work the way you would initially think it would.

I had this exact problem earlier this week and had to explain it to two different people in the two days after that. So why not write it down in a blog post?

Suppose you have this silly implementation of a class that takes a file path and reads the file’s content into a variable that can be accessed through a property:

class SillyFileReader(object):
    def __init__(self, file_path):
        self._file_path = file_path
        self._content = self._read_file()
    def _read_file(self):
        with open(self._file_path, 'r') as f:
    def content(self):
        return self._content

You also have this equally silly function that takes an instance of the silly file reader and returns the reversed content:

def silly_reverse_content(silly_file_reader):
    return silly_file_reader.content[::-1]

Of course you want to test this silly function. Maybe you come up with something like this:

import mock
import unittest

class SillyTest(unittest.TestCase):
    def test_silly_reversing(self):
        mock_reader = mock.MagicMock()
        mock_reader.content = mock.PropertyMock(return_value='silly')

        assert silly_reverse_content(mock_reader) == 'yllis'

Unfortunately, that won’t work:

TypeError: 'PropertyMock' object has no attribute '__getitem__'

The thing with a PropertyMock is that you need to set it for the type of an object, not for the object itself. To get things working, you need to do it like this:

class SillyTest(unittest.TestCase):
    def test_silly_reversing(self):
        mock_reader = mock.MagicMock()
        type(mock_reader).content = mock.PropertyMock(return_value='silly')

        assert silly_reverse_content(mock_reader) == 'yllis'

That’s it!

Running Jekyll locally with Docker

This website is built with static site generator Jekyll and hosted on GitHub pages. There are a number of reasons why this combination is awesome:

  • I can write everything in Markdown
  • The workflow has source control baked in
  • The website is automatically updated by pushing to master

If you want to give Jekyll a go and you’re running Linux or OS X, you have to make sure you have the correct version of Ruby and some gems installed. Running it on Windows isn’t officially supported, but it can be done using Chocolatey and it also requires Ruby and some gems. Regardless of your operating system, there is an easier way to get Jekyll running on your machine. This is where Docker comes into play.

When you run Jekyll from inside a Docker container, you won’t have to bother with installing a specific version of Ruby or with different versions of gems you already had installed potentially clashing. You could of course use the Ruby Version Manager, but working with Docker really is a breeze.

The rest of this post assumes you have Docker and Docker Compose installed and have some basic knowledge of working with it. Docker has some great getting started guides for Linux, Mac and Windows.

The easiest way to get started is probably to download a theme for Jekyll. This website uses a slightly modified version of the Hyde theme. It’s hosted on GitHub, so you can download or clone it from there.

The friendly people of Jekyll have already made a Docker image available on Docker Hub. Let’s take advantage of that! Suppose you have downloaded or cloned the Hyde repository into ~/jekyll-site/. To use the Jekyll image without having to pass in the required options every time to create a container, we can make use of Docker Compose. Create a file called docker-compose.yml in ~/jekyll-site with these contents:

    image: jekyll/jekyll:pages
    command: jekyll serve --watch --incremental
        - 4000:4000
        - .:/srv/jekyll
  • With image: jekyll/jekyll:pages you indicate you want to use Jekyll’s Jekyll image tagged with “pages”. This is a specific image suited for GitHub pages.
  • The part after command: is the command to execute in the container. The jekyll serve command starts Jekyll’s builtin development web server. The options --watch and --incremental instruct Jekyll to automatically regenerate the HTML when a file is changed.
  • 4000:4000 forwards port 4000 of the container to your local port 4000.
  • Finally, on the last line you map the current directory (~/jekyll-site/) to /srv/jekyll/. That’s where the images is configured to go looking for a Jekyll site.

That’s all! You can start your Jekyll site by browsing to your site’s directory using a terminal and doing docker-compose up. You will see something like this:

jekyll_1  | Configuration file: /srv/jekyll/_config.yml
jekyll_1  |             Source: /srv/jekyll
jekyll_1  |        Destination: /srv/jekyll/_site
jekyll_1  |  Incremental build: enabled
jekyll_1  |       Generating...
jekyll_1  |                     done in 0.343 seconds.
jekyll_1  |  Auto-regeneration: enabled for '/srv/jekyll'
jekyll_1  | Configuration file: /srv/jekyll/_config.yml
jekyll_1  |     Server address:
jekyll_1  |   Server running... press ctrl-c to stop.

If you go to (or the IP of your VM if you’re running Docker on OS X or Windows) in a browser you’ll see your Jekyll site. Easy, right?