You can do a lot of good stuff with the Python/C API. However, bear in mind that Python has exceptions and so you have to deal with them even when you’re using its C API. If you’re using the Python/C API and forget to check and handle exceptions I can say your program will probably crash with some weird exception at some weird place (believe me, been there). And what it’s worse: it won’t be easy to find where is the problem! (you can find how to do exception handling with Python/C API here).

If you are using h2def.py/codegen.py to generate Python wrappers for your GObjects do pay attention to these messages:

Warning: Constructor for <your GObject here> needs to be updated to new API.
              See http://live.gnome.org/PyGTK_2fWhatsNew28#update-constructors

That has the consequence that you’ll have problems subclassing the wrapped objects. That page doesn’t exist but you can see the explanation and how to solve it here.

So I was generating Python wrappers for some GObjects in C with h2def.py/codegen.py/scanvirtuals.py and I wanted to access a class variable in my classes (if you don’t know the difference between class and instance variables in Python, read the programmer’s note on this page). However, I couldn’t find an easy way of doing this until I found this function:

pyg_register_class_init(GType, PyGClassInitFunc)

It can add a function to be called when the class for that GType is initialized. That solved my problem because I only had to register a class init function for my base class. This function verifies if my python class has a specific variable and just uses it if it has or raises an exception if it doesn’t. Simple and to the point but if someone has a better way of doing this, just post a comment, please. :-)

After a long time with nothing new here I’ll try to post something at least once a month (I hope I can do it :-).

Now let me say a few words about what has happened in the first half of 2007. After being directly involved with BlueZ and CarMan development I went to Germany for three months to do a consulting work on Maemo and embedded Linux in general. Overall, it was a nice experience but I’m really glad to be back in Brazil among my friends and relatives.

I’m back in Brazil for over a month now and I’m working on the new version of Canola with the rest of the team. I’m working in the infrastructure of this new Canola in Python and also in the low-level integration of CarMan (see this post from Marcelo). I’ll try to post later some of the glitches and things I’ve been working on lately. Stay tuned, because we’re working hard to make this new Canola rock even more! :-)

If you ever wanted to know more about linear programming and how to use GLPK go check this article written by Rodrigo Ceron! He carefully explains some theory on linear programming and how to use GLPK to solve problems. I must say that linear and integer programming are very interesting topics. I should find some time to study these areas a little bit more. This article reminded me of PuLP, a nice linear programming modeler for Python that can use GLPK as its underlying solver.

Update: another GLPK article by Rodrigo Ceron! Go check it out!

I’ve recently bought a Linksys WRT54GS v4 wireless router and installed OpenWRT last saturday. OpenWRT is really neat and its web interface does exactly what you want. Another point worth mentioning is that ipkg seems to work flawlessly (so far). It’s nice to see projects like this one because we can see that Linux supports more hardware than anyone else (Greg KH is just right) and we can make very good GNU/Linux systems to fit whatever our needs are. Cool!

Yeah, I can hear you saying I should do one post for each one of the things I’ll comment here, but… I think it’s too late for that. :-)

Well, first of all, OLS was really fun. Meeting people, seeing some of the most famous persons like Alan Cox and Andrew Morton and getting to know what are the trends in Linux kernel development now was great. I can say that new file systems, virtualization and power management were the main topics. I’ve also met Iñaky Pérez-González and we’ve talked about contributing code to the UWB project. Let’s see if we can work that out. :-)

OLS itself was great, but going to Ottawa and coming back home turned out to be really painful. We missed a flight on our way to Ottawa and arrived there only 28 hours after we left Recife. However, coming back home was even worse. It took us 48 hours to come back home because United Airlines screwed us badly by overbooking our connection in Washington. Since they have only two flights to Brazil, we had to wait a whole day to fly to Sao Paulo. But this wasn’t enough for United, we weren’t confirmed for the next flight, we’re only waitlisted and that meant we could stay another day in Washington! This was really disrespectful. Arriving in Sao Paulo was another nightmare, because we’ve already lost our connection there (of course) and had to wait several hours to fly to Recife. After all this drama we’ve managed to get back home safe. United sucked big time. Grrrr…

Going to OLS was really good and now I have lots of things to do for BlueZ (thanks to Marcel Holtmann :-) and lots of ideas related to virtualization. I’m thankful that INdT sent me there. It’s time to work hard now..

I think it’s nice to travel but coming back home is even better! I really missed Dotty (my beautiful girl and future wife :-) while I was in Ottawa. Maybe we can go there together some other time.. :-)