We Don’t Need No Enums (in Python)

Last weekend I attended the PyGrunn conference, back in the good ol’ Netherlands. It was a very enjoyable and instructive event, featuring not only a few local speakers but also some prominent figures from the Python community – like Kenneth Reitz or Armin Ronacher. Overall, it was a weekend of some great pythonic fun.

…Except for a one small detail. As I’ve learned there, Python will apparently get to have enums in the 3.4 version of the language. To say that this was baffling to me would be a severe understatement. Not only I see very little need for such a feature, but I also have serious doubts whether it fits into the general spirit of Python language.

Why so? It’s mostly because of the main purpose of enumeration types, derived from their usage in many languages that already have them as a feature. That purpose is to turn arbitrary data – mostly integers and strings – into well-known, reliable entities that can be safely manipulated inside our programs. Enums act as border guardians, filtering out unexpected data and converting expected data into its safe representation.

What’s safety in this context? It’s type safety, of course. Thanks to enumeration types, we can be certain that a particular value belongs to specific and constrained set of elements. They clearly define all the variants that our code should handle, because everything else was already culled at the conversion stage.

Problem is, in Python there is nothing that would guarantee those safety promises are actually fulfilled. True, the basic property of enum types is retained: given an enum object, we know it must belong to a preordained set of entities. But there is nothing that ensures we are dealing with an enum object at all – short of us actually checking that ourselves:

How this is different from a straightforward membership check:

except for the latter looking cleaner and more explicit?…

This saying, I do not claim enums are completely out of place in Python. This is untrue, if simply because of the fact they are easily implemented through a rather simple metaclass. In fact, this is exactly how the proposed enums.Enum base is supposed to work.
At the same time, it is also possible to provide some of the before-mentioned type safety. Just look into various libraries that enhance Python with support for contracts: a form of type safety which is even more powerful than what you’ll find in many statically typed languages. You are free to use them, and you should definitely do, if your project would benefit from such a functionality.

Incidentally, they fit right in with that new & upcoming enumeration types from Python 3.4. It remains to be seen what it means exactly for the overall direction of the language design. But with enums in place, the style of “checked” typing suddenly became a lot more pythonic than it was before.

And I can’t say I like it very much.

Here Be Dragons: Game from IGK Compo

Last weekend I had the pleasure to attend the game development conference IGK in Siedlce, Poland. Although gamedev is not something I normally do, it was a fun experience.

One thing I was especially looking forward to was the one day-long game programming contest called Compo. Like last year and the one before, I formed a team with Adam “Reg” Sawicki and Krzysztof “Krzysiek K.” Kluczek, guest starring Kamil “Netrix” Szatkowski. That’s four coders in total, so we kinda had some problem with, say, more artistic part of the endeavor :)

Nevertheless, the result was pretty alright: we scored 4th place out of about dozen teams. The theme this time was an “artillery” game with few mandatory features: two types of energy-like resources (HP & MP), achievements and multiplayer gameplay.
We nailed the last one by implementing support for two mice at once. This allowed us to come up with an interesting idea inspired by the Atari game Rampart: two castles that expand and attack each other in a fast-paced duel full of frantic clicking. And because the attackers, or guardians of each castle are dragons, hence the game’s title: Here Be Dragons.

  [2013-04-07] Here Be Dragons (3.2 MiB, 1,725 downloads)

In retrospect, we should probably have narrowed the scope of our project more. Doing it 3D was ambitious in itself, but packing it with all the features we planned the night before turned out to be slightly too much :) In the end we didn’t even have time to code any sound effects or music!… That’s certainly a lesson to learn here.

But all in all, it was great fun. It certainly inspired me to maybe try and brush up my gamedev skills a bit more :)

Slides from My Talk at Name Collision

Last Friday I had the pleasure of attending the Name Collision hackathon in Warsaw. I haven’t actually taken part in the competition but I served as a mentor, trying to help the teams get stuff done as much I could. It was really fun experience.

Before that, though, I gave a short lightning talk about the Git version control systems. I showed a few (hopefully) lesser known tricks that may prove useful both in everyday workflow and in some exceptional situations.
The slides from this talk are available here. They might be a bit uninformative on their own but I suppose the liberal use of memes can make up for this somewhat ;-)

Ego-Driven Technologies

Last week – while still on the other side of the pond – I attended a meet-up organized by the local Google Developers Group. The meeting included a presentation about Go, aimed mostly at newcomers, which covered the language from the ground up but at very fast pace. This spurred a lot of survey questions, as people evidently wanted to assess the language’s viability in general and fitness for particular domain of applications.
One of them was about web frameworks that are available to use in Go. Answer mentioned few simple, existing ones, but also how people coming from other languages are working to (re)build their favorite ones in Go. The point was, of course, that even though the language does not have its own Django or Rails just yet, it’s bound to happen quite soon.

And that’s when it dawned on me.

See, I wondered for a while now why people are eager to subject themselves to a huge productivity drop (among other hardships) when they switch from one technology, that they are proficient in, to a different but curiously similar one.
Mind you, I’m not talking about exploratory ventures intended to evaluate language X or framework Y by doing one or two non-trivial projects; heck, I do it very often (and you should too). No, I’m talking about all-out switching to a new shiny toy, especially when decided consciously and not through a gradual slanting, in a kind of “best tool for the job” fashion.

Whenever I looked for justification, usually I’d just find a straightforward litany of perks and benefits of $targetTechnology, often having a not insignificant intersection with analogous list for the old one. Add the other, necessary part of risk-benefit calculation – drawbacks – and it just doesn’t balance out. Not by a long shot.

So, I notice that I am confused. There must some be other factor in play, but I couldn’t come up with any candidates – until that day.
As I speculate now, there is actually a big incentive to jump ship whenever a new one appear. And it seems to be one of dirty secrets of the hacker community, because it directly questions the esteemed notion of meritocracy that we are so eager to flaunt.

Prison Escape: Game from IGK Compo

Yesterday I came back from IGK conference (Engineering of Computer Games) in Siedlce. Among few interesting lectures and presentations it also featured a traditional, 7-hour long game development contest: Compo. Those unfamiliar with the concept should know that it’s a competition where every team (of max. 4 people) has to produce a playable game, according to particular topic, e.g. theme or genre. When the work is done, results are being presented to the public while a comittee of organizers votes for winners.

As usual, I took part in the competition along with Adam Sawicki “Reg” and Krzystof Kluczek “Krzysiek K.“. Topic for this year revolved around the idea of “escape” or “survival” kind of game, so we designed an old school, pixel-artsy scroller where you play as a prisoner trying to escape detention by running and avoiding numerous obstacles. We coded intensely and passionately, and in the end it paid off really well because we actually managed to snatch the first place! Woohoo!

A whopping amount of 15 teams took part in this year’s Compo, so it might take some time before all the submissions are available online. Meanwhile, I’m mirroring our game here. Please note that it uses DirectX 9 (incl. some shaders), so for best results you should have a non-ancient GPU and Windows OS. (It might work under Wine; we haven’t tested it).

  [2012-04-01] Prison Escape (5.8 MiB, 1,911 downloads)

Prezentacja o C2DM

Zamieszczam slajdy z prezentacji, którą wygłosiłem dzisiaj w ramach Polidea Talks. Dotyczy ona androidowego wynalazku znanego jako Cloud to Device Messaging (C2DM) i będącego odpowiednikiem apple’owych Push Notifications z systemów iOS i OSX. Dla nie do końca zorientowanych spieszę z wyjaśnieniem, iż jest po prostu dość sprytny sposób na to, by urządzenie mobilne mogło “natychmiast” otrzymywać informacje ze zdalnego serwera – bez konieczności regularnej synchronizacji, która zużywa baterię i nie tylko.

  Push! - Instant notifications on Android through C2DM (591.7 KiB, 1,974 downloads)

Slajdy są tym razem w klasycznym PDF-ie. Chwilowo nie mam żadnej lepszej alternatywy dla starego, dobrego PowerPointa :)

GDD w Pradze

Miałem ostatnio okazję wzięcia udziału w jednej z lokalnych edycji konferencji Google Developer Day. Na to wydarzenie składa się cykl wykładów prowadzonych przez przedstawicieli Google, traktujących o technologiach webowych, mobilnych i tym podobnych tematach. GDD, w którym akurat ja uczestniczyłem, odbywał się wczoraj w Pradze.

Przyznam, że nigdy wcześniej nie brałem udziału w podobnym wydarzeniu, więc było to bardzo interesujące doświadczenie. Większość z prezentowanych tematów wydawała się niezwykle ciekawa, a ze względu na to równoległy przebieg aż pięciu ścieżek wykładowych należało dokonać bardzo trudnego wyboru, których sesji chcemy posłuchać. Miejmy nadzieję, że wszystkie tak czy siak wkrótce trafią na YouTube :)

Od siebie dodaję kilka zdjęć. Ich jakość nie jest aczkolwiek powalająca, bo zostały wykonane sprzętem, którego główne przeznaczenie jest zgoła odmienne ;)

Update: Oficjalna galeria zdjęć z imprezy jest już dostępna.