the summer of busy

So far this summer is being much busier than usual.

A couple of weeks ago I attended the html 5 hack-a-thon organised by the Dublin GTUG guys. It was real fun and got to meet some very interesting people and to hack on a browser multi-user whiteboard based on WebSockets and canvas. All the projects were really good, and the effort during the two days paid off big time.

Last week we were busy working on a rails mountable engine to add feedback forms to your web during the Ruby Project nights at amworks. Only a few hours there but it's great to be able to learn and share socially out of work hours, at least from time to time!

In the meantime all is good to go for the code retreat we are organising for September the 17th. Location and sponsorship is pretty much all we needed, and we are looking forward to the day. Tickets flew in less than 3 days, so hopefully people will turn up on the day. If you are reading this, have a ticket, and know for sure that you cannot attend, please let us know cause we have a growing waiting list.

And finally, all is ready for the dublinjs meet up tonight in which Wiktor will tell us all about CoffeScript and Dom has prepared a Kata for us to go through. Great fun ahead!!!

Dublin JavaScript Group July meet up -- Kata Reloaded!

We are organising another Kata session for the Dublin Javascript meetup this month, which will happen tomorrow Tuesday the 19th at 6.30pm @amworks. You can sign up here.

These are my slides for the event, which are pretty much the same as the ones I used last month.


The initial idea was to have a presentation on Processing.sj although that has been postponed, but I'm sure Nigel will come up with something. And in any case we are going ahead with uncle Bob's Prime Factors Kata.

The solution, in the form of a powerpoint document, can be found here so you don't really have to worry about the solution itself and can focus on practising the Kata instead.
A couple of interesting points I've noticed after practising it a couple of times are the differences between his Java implementation and a JavaScript one, and my mixed feelings to his last refactoring, which I find a bit contrived. I prefer to stop at the level of 'while' structures because I believe it preserves the intent of the algorithm a lot more than if you go the whole way and replace them with 'for' structures. The result has more lines of code but in my head it's clearer. But as usual, this is a personal preference and everyone will have their own, which is a good thing!

The format for this part of the meetup will be the following:
I will go through the slides, which will take me about 3 minutes. Then we will set about 20 minutes for people to work on the Kata. Working in pairs using ping pong pairing would be highly recommended. The idea is that one person writes the first test, the other person makes that test pass and writes the following test, and this goes on until the Kata is solved. If you don't want to pair, that is fine. If you don't want to program at all, that is fine too!
During those 20 minutes I'll be available to help out, especially to any new faces that are not familiar with the concept of a Kata or with Jasmine. At then end of this period we will project one solution and have a short retrospective about it.

And that is all, please feel free to join us from 6.30pm at amworks. See you there!

Dublin JavaScript Group June meet up -- jQuery and Jasmine

In a couple of hours the JavaScript Dublin Group will meet up for the second time. The first meetup was last month, and it was basically a gathering to get to meet other people and talk a bit about organisation.
So this will be the first time for a technical session. Nigel Kelly will be talking about jQuery apps, and I will run a Kata session in JavaScript using Jasmine. I hope people will follow along. We will use the standalone version of Jasmine and the kata chosen for the session is Fizz Buzz.

I came up with the following 4 slides (yeah, want to keep it short!):



The slides will not make much sense on their own, so you better come to the meet up!


This means that I will miss the P2PU SICP study group session on IRC (freenode #sicp room) today at 7pm GTM, 3pm EST, but it's for a good cause, right? :)

learn, laugh and move on!

There's been a lot going on lately and as a professional procrastinator I couldn't let go the chance of putting off writing a new blog post, but with things going back to normal (hopefully!) it's about time for a bit of reflection.

It's been a very social few weeks, ending May with a double bill: The software craftsmanship conference in Bletchley Park, and a coding day with the chaps of codingday.org here in Dublin.

What can I say about scuk11? it was a great day with fantastic sessions and I got to meet a great bunch of Spaniards in red t-shirts. Happy faces all over... yeah, the bar was already open!

The Dublin event was also fantastic and although it was first thought as a coderetreat, the addition of scientists and their real problems changed the nature of the session itself and made of it a fantastic coding day. The group I was working with got a spinning cube in the browser, with three different lights and three particles lighting up the cube with different colours. Great fun using the Three.js library!

The month of June started with @silverspoon organising hack nights in a café near the city centre, that I sadly missed because I was in Barcelona for a conference. Spain was great, as usual, although it was raining most of the time, but that didn't really have an impact on things such as meeting old friends, the great conversations we had, and of course, the fantastic food!

On Tuesday the 14th we had the first meet up for the SICP study group at P2PU. You can see what happened in the new wiki. This is an open group which basically means that you can join in anytime that suits you. We will meet twice a week for the next couple of months, Tuesdays and Sundays at 7pm GMT, 3pm EST. We are hoping to finish a section every two weeks, including exercises. As chapter one of the book has 3 sections, we are hoping for a 6 week period to be done with it. Wish us luck!!! or even better, join in!!!

Last night the first Ruby Project Night happened in armworks. The space is absolutely great and I want to thank Alan for hosting it. We didn't really know what to expect at first, and after a bit of chat and trying to get the projector going, we started hacking away in a rails 3 gem, something that none of us had done before. We didn't get too far but at least we got it packing and installing fine. As soon as the @theirishpenguin pushes it publicly I will share the link here. It was great to meet a bunch of enthusiastic people and looking forward to meeting them again!

This morning I read this 'Help Wanted' message from @oisin in the ruby Ireland list. If you are looking for contract Ruby work you should definitely get in touch with him. His last talk at ruby Ireland was really interesting.
In the thread he mentions that they like egoless programming which brought me back to the this old post of mine. Weingberg's book is a very recommended read even if as myself, you were not even born when it was written!

An finally, more to look forward to as the first 'technical' meet up of the Javascript Dublin group will be next Tuesday 21st at 7pm. A presentation about jQuery for web apps and a kata with Jasmine are in the menu. Are you really going to miss that???

Mutant-Java and the KataLonja

Another month and another Kata with the 12meses12katas crowd. This time the kata is in Spanish, and it was created by the agilismo.es guys for the professional track of XGN2011. If anyone needs/wants a translation, do get in touch and I'll produce one. You can find the original version in github: KataLonja.

The Kata is about a Galician chap who wants to make some money by selling Scalops, Octopus, and Spider Crabs in a hired van. We are given a series of prices that markets in different cities will pay for the goods, alongside with distances, transport costs, and depreciation rates for the food, and we need to provide the most interesting route to get a best sale for our intrepid entrepreneur.

As a Galician immigrant myself, this is the simplest kata ever: I would drive the van right into my garage and the goods straight into my fridge; as easy as that!

Sadly this is not going to happen so let's get back to the kata. I'm certainly nowhere near finishing it, I only gave it a first go last night before bed but some cool stuff is already coming up out of it.
As I mentioned in a previous post, I use Katas to refresh some concepts that I haven't seen in a while, or that although I might use them in my day job, I've never gone deeper at them than the old getting the job done.
Last month I choose JavaScript for the bowling kata, and because I started way too late (the last day of the month!), that was the only implementation that I practised on the day. I will try and get this one practised in both Java and JavaScript, starting with the former.

Java has no associative arrays and it's generally accepted that you will use Maps instead. Maps can be very straight forward if you are using an immutable object as the key for your pair, but can get tricky if you decide to use your own class. So that's exactly what I did. It might not be the best fit for the problem at hand, or yield the leaner and cleaner code possible, but no one will have to maintain this code and it's going to be thrown away anyway so better have a bit of fun with it!

So I have created an immutable class for Seafood that I will be using as a key for at least two maps I'm using in other classes. That means overriding equals() and hashcode(), and being careful with state and escaping references to this. But as I said above, the code is nowhere near written, so what's the point of the post you will be asking yourself? I just wanted to share 3 links that have been helpful in digging a bit deeper in the adventure so far. They are:

• Hashing it out!
• To mutate or not to mutate?
• How to write an equality method in Java

In them you will find good advice on stuff such as when to create immutable classes and how, uses of immutability including the flyweight pattern, overriding equals() and hashcode(), and a great discussion on how to keep the equals() contract on extended classes, adapted from the book Programming in Scala into Java.

I will be digging a bit more, hopefully in the next couple of days, in topics such as choosing the right map implementation and a couple more things that I want to try (I'd like to write my cucumber step definitions in Ruby instead of Java but I'm not sure I can do that, so will have to find out!).
I also intend to write another post if I ever get to practise the Kata in JavaScript. Comparing both implementations would be cool so let's hope for that!

Roman Numerals Kata

Last month I joined an initiative by a group of Spanish Agile followers called 12 meses 12 Katas. The idea is that each and every month during 2011, we will be practising a Kata, and sharing our code through github, and for those adventurous enough to record themselves, also through this vimeo channel.

There is a ton of resources in the net about what a Kata is and why are they important so I will not get into that, but I would like to stress the last bit of pragmatic Dave's definition:

"[...] remember that the point of the kata is not arriving at a correct answer. The point is the stuff you learn along the way."

After having practised the February Kata a bunch of times, I wanted to write a bit about the process and reflect on my own deliberate practice and learning journey during these last couple of weeks.

When I first saw the Kata, I thought it was going to be easy peasy. Yes, totally missed the point; it's not about the problem but about practising it, but in any case, I was so very wrong! It turned out to be a lot more complex than anticipated, and I even thought for a couple of days that I was having some type of programmers block. Sticking to strict TDD didn't help much either, when you are not as used to use it as you first thought!

I went through 3 different solutions:

The First solution was very complex and it was very influenced by Maths. I was tracking all this positions for different numbers, and had a ton of if branches and all that. Messy!

Then I saw a recursive solution to the Kata. YES, I SAW IT; call it cheating if you want to, I couldn't care less. When I saw the simple solution, it made me think...Why did I start coding without thinking a bit about the problem itself. I should have a look at the relations among numbers, which ones are the special cases, and so on. In a nutshell, the Domain is very important, even in small projects. That was Lesson one for me, hope it sticks!

I'd say it has to do with our nature or background as scientists. That initial thought of 'I can do this with a bit of math', yields an answer, but it is too complex, not so difficult to write, but long, and difficult to maintain. A quick but thorough look at the domain shows that the cases can be simplified if you play a bit with them. Special cases such as 4, 9, and all numbers terminating in any of the two, can be easily automated.

So I started working on a recursive solution. At first I wrote a recursion with a wonky base case, and it worked anyway on one direction (arabic to roman), but it did not for the opposite. There was a mix here of problems with copy by value in Java, and objects and primitives. If it hadn't been for the primitive case, I wouldn't have noticed the flaw in the recursion. Which leads me to think that test are great, but obviously not a silver bullet! You still have to get the algorithm right! Another example of this can be seen in my video, when I mix up L and D in the tests themselves! So Lesson two is: no silver bullets. 

Recursion can feel easy at times, but when it is easy to write, it makes you wonder if there is another way. And in fact there was. In this case a simple loop could yield the same results as the recursion, and that was my last solution.

I feel that I have a better understanding of what Katas are good for, after practising them deliberately for the last couple of months. When you are in the job, you just go to the point, and choose a collection, or refactor to an iterative process, but you don't get to dig out more information. Doing the kata in my own time, I consider that spending some of it in the details of how to choose that collection, or when to refactor is far more beneficial. This is something I had read about before, but never experienced by myself. Lesson three: deliberate practice is necessary.

What else did I learn/review this month?

- review of Maps in Java (mainly due to the fact that I needed order in my collection). Although I started the kata with arrays (some people will say that it was faster and all that), I decided to go for a map in the end, cause having two different arrays (one for arabic numbers and one for their roman counterparts) was not expressing the intent of the mapping. 

- review of recursion and refactorings applied to the recursion itself. Interesting to find out that most newish compilers will automatically substitute a tail recursion for an iteration for you, so if the intent of the algorithm is clearer with the recursion, I will definitely go with that form from now on.

- I wanted to use cucumber for acceptance testing so finally got to set up cuke4duke to run cucumber features on Java programs. It is so much fun!

- Writing cucumber features has reminded me (yet again) of my little knowledge of regular expressions. Also brings up the fact that writing features is a lot harder than reading somebody else's. Hopefully if I use them more, both things will stick in my brain, at least the basics anyway!

- Lastly, it has been quite strange to watch my kata after recording it. Does not feel like it is me (especially due to my supersonic typing up speed! Nah, it's fake, I've doubled up the speed cause the Kata was far too long!). It's definitely the case that what you think you are doing and what you actually do are two different things. The more I see it, the more I'd like to change things. But I think that that is good anyway!

As I mentioned earlier, the kata was a bit long for a video so I have sped it up! Generally katas are recorded with a piece of classical music as background. I've chosen a piece from my extensive collection, which pretty much means that it was the only 1 out of 6 classical tracks in my itunes that was long enough for the video!!! Hope you enjoy it!


Roman Numerals Java + cuke4duke (Double speed) from Josmas Flores on Vimeo.