/devel

It’s been a while since I used Python for anything larger than scripts few tens lines long, so it feels really great to do it again. I did discover however that I became a bit rusty. Not so much in not being able to achieve what I want as not being sure that I do it in a sensible and pythonic way.

I’ve been working on a private project where I came to a following problem. API calls can trigger various responses, somewhat like HTTP, containing status codes together with a short description. Every faulty response should trigger its own exception, which led me to my first implementation:

class Unauthorized(Exception):
    status = 101
    value = "Unauthorized."

I didn’t like it even though it looks and behaves like it should. What I wanted was a better overlook of possible responses in a way where I have to make any possible changes easily and only at one place.

My second attempt was auto-generating exception classes using type. Since class definition took only a line instead of three, it certainly achieved better transparency, but I still had to make changes at two places.

Final step was to auto-generate classes in a loop. To do this I attached them to module namespace using globals() dictionary. Actually I used __builtin__ one at first, but it obviously didn’t work that great.

So this is what I have now. It works and achieves my goals. I only need to change dictionary to add a new response or change existing one and it could hardly be more readable.

But is it pythonic enough? If not, what would be, apart from traditional way described in first step?

EuroPython 2008 is over. I packed and now I am waiting to leave for the airport to catch afternoon flight back home. Sadly I don’t have time to attend sprints and since I only recently started to write python again, I probably wouldn’t be of much use anyhow.

Conference itself was great. Smaller than web conferences I usually attend with a more friendly, homey feeling, but with plenty of excellent talks where I learned a lot. I also met a bunch of friendly interesting people and had in general a wonderful time.

It was also interesting to compare the whole experience with other conferences I go to. Apple is popular, but there are fewer Macs than at web events. Ubuntu seems to completely dominate Linux crowd (me included), since it was the only distribution I actually have seen and Windows is in minority. Everyone is much more willing to participate to the point, where sadly not all who wanted to present a Lightning talk on last day had the opportunity to do so.

I certainly hope to attend EuroPython 2009, which will be in Birmingham around this time next year. At the end I also have a present. Yesterday I got a license for Wing IDE Professional and since I don’t need one, I’ll give it to the first person who expresses a wish to have it in comments and leaves his/her email address in relevant part of comment form.

Update: License is gone, sent to a new owner.