Posts Tagged ‘python’
Packaging, testing, pypi and my Pycon Russia adventures
Besides the good feedback and discussions around my talk, i just had a great few days. It was my first time to Russia and i saw and learned a lot. One unexpected event was going to a russian Sauna with Amir Salihefendic, Russel Keith-Magee and Anton, a main conference organizer. Between going into the Sauna we had glasses of nice irish Whiskey or walked outside to the snowy freezing cold. Afterwards some of us went to the conference party and had good (despite being somewhat drunken) discussions with people from Yandex, the biggest russian search engine and several russian devs. All very friendly, competent and funny. The party lasted until 5:30am – with my fellow english-speaking talkers Armin Ronacher, David Cramer (a weekend in Russia) and me being among the very last.
David, Amir, Russel, and our russian hosts
The next days evening saw Amir, David, Armin and two russian guys visiting an Irish pub past midnight. It turned out there is no such thing as a “russian pub”, the concept of “pub” was imported in the last decade mostly in the form of english or irish ones. And it seems IT/Python guys can meet everywhere on the planet and have a good time 
Ice, Ekaterinburg at night, and an anonymous shop
Going back to content, i felt particularly inspired by Jeff Lindsay’s talk on Autosustainable services. He described how he tries to provide several small web services, and how to organize cost sharing by its users. As services need resources, it’s a different issue than Open Cource collaboration which does not require such to exist.
I heart several good sentences from my fellow talkers, for example one from Russel Keith-Magee describing a dillema of open source communities: “There are many people who can say ‘No’ but few who can say ‘Yes’ to something”. Amir Salihefendic desribed how the “Redis” database solved many problems for him, and some interesting concrete usages of “bitmaps” in his current endeavours like bitmapist.cohort. And of course Armin Ronacher and David Cramer also gave good talks related to their experience, Advanced Flask patterns and scalable web services respectively. With Armin i also had a good private discussion about the issue of code-signing and verification. We drafted what we think could work for Python packaging (more separately). With David, i discussed workflow commands for python packaging as he offered some good thoughts on the matter.
Around the whole conference we were warmly cared for by Yulia’s company it-people.ru who overtook the physical organisation, and by Anton and his friends who organized the program. Maria Kalinina in particular had cared for the keynote speakers and many other aspects of the conference, and without her, i wouldn’t have made it. Anton drove us to the Asian European geographic border, and Yulia to the skyscraper of Ekaterinburg, overlooking the third largest city in Russia. Russel and me also took the opportunity to walk around Ekaterinburg, looking at Lenin sculptures, buildings made of ice, frozen lakes, and the many shops and noises in the city.
Iced lake, Lenin forver, The Asia/Europe border
Lastly i went to the university with Russel to talk for two hours to students about “How Open Source can help your career” and we had a lively discussion with them and the lecturer who invited us. I offered my own background and stated that the very best people in the IT world are today collaborating through open-source. It’s a totally dominant model for excellence. (Which doesn’t mean there are not some good proprietary projects, they are just fewer i’d say).
So i can join the many russian participants who thought Pycon Russia was a very good conference. It’s of course mostly interesting for people speaking russian, as only seven talks were in english. For my part, the intense time i had with both the russian hosts and developers and the english talkers was verymuch worth it – i think there might be a few new collaborations coming from it. More on that in later blog posts hopefully
Two days ago i left Ekaterinburg and felt a bit sad because of the many contacts i made, which almost felt like the beginning of friendships.
metaprogramming in Python: What CPython, PyPy, Pyramid, pytest and politics have in common …
Metaprogramming in Python too often revolves around metaclasses, which are just a narrow application of the “meta” idea and not a great one at that. Metaprogramming more generally deals with reasoning about program code, about taking a “meta” stance on it. A metaprogram takes a program as input, often just partial programs like functions or classes. Here are a few applications of metaprogramming:
- CPython is a metaprogram written in C. It takes Python program code as input and interprets it, so that it runs at a higher level than C.
- PyPy is a metaprogramm written in Python. It takes RPython program code as input and generates a C-level metaprogram (the PyPy interpreter) which itself interprets Python programs and takes another meta stance by generating Assembler pieces for parts of the interpreation execution. If you like, PyPy is a metaprogram generating metaprograms whereas CPython and typical compilers like GCC are “just” a metaprogram.
- Pyramid is a metaprogram that takes view, model definitions and http-handling code as input and executes them, thereby raising code on a higher level to implement the “Pyramid application” language.
- pytest is a metaprogram written in Python, taking test, fixture and plugin functions as input and executing them in a certain manner, thereby implementing a testing language.
- metaclasses: in Python they allow to intercept class creation and introspect methods and attributes, amending their behaviour. Because metaclass-code usually executes at import time, it often uses global state for implementing non-trivial meta aspects.
Apart from these concrete examples, language compilers, testing tools and web frameworks all have metaprogramming aspects. Creating big or small “higher” level or domain-specific languages within Python is as a typical example of metaprogramming. Python is actually a great language for metaprogramming although it could be better.
In future blog posts i plan to talk about some good metaprogramming practise, particularly:
- keep the layers/levels separate by good naming and API design
- define a concise “language” for the programs you take as input
- avoid creating global state in your metaprograms (and elsewhere)
which can easily happen with meta-classes executing at import time
Lastly, i see metaprogramming at work not only when coding in a computer language. Discussing the legal framing for executing programs on the internet is some kind of metaprogramming, especially if you consider licensing and laws as human-interpreted code which affects how programs can be written, constructed and executed. In reverse, web applications increasingly affect how we interact with each other other, thereby implementing rules formerly dealt with in the arena of politics. Therefore, metaprogramming and politics are fundamentally connected topics.
have metafun, i. e. take fun stuff as input to generate more of it holger
