Subclassed

09 March 2010

The joys of Python and Qt

I'm currently working on a tutorial regarding MeeGo, the new Linux-based embedded platform born by the merging of (Nokia-sponsored) Maemo and (Intel-adopted) Moblin. MeeGo is probably the closest thing we'll ever get to a real "Linux for the masses": differently from Android, where Linux is just a kernel for Java to run on top, here we'll have the full GNU toolchain, X display, desktop technologies based on FreeDesktop standards, RPM packages, etc etc.

The main development toolkit for MeeGo, from now on, will officially be QT. This seems to fly in the face of reason, having two existing GTK-based codebases from both "parent" systems which have already been deployed on production devices, but it's actually a very smart choice, as I was reminded just today.

This morning, I was working on a laptop running Windows XP. I built a couple of forms with Qt Designer, then fired up my trusty IDE and wrote the main code, about 150 lines of Python that will download some files, manage a few controls and then display a web page.

After completing a full set of tests on the local machine, I copied it to my (Maemo) phone, and again it was working perfectly -- without any change, recompilation, deployment, anything. Then I went home and copied it back to a different laptop running Kubuntu Linux, and again it was running just fine. Had I had a Mac (or iPad?) laying around, I'm confident it would have run there as well without any change. Consider that the version of QT and PyQt was slightly different on all machines, just to give it a further twist.

Obviously this level of portability has a price. I had to write my code using constructs like QSettings and QNetworkAccessManager rather than messing directly with the Windows Registry or HTTP_PROXY variables. I have yet another (leaky) abstraction layer on top of the OS, which may or may not be to everyone's taste, and the program runs in a sandboxed runtime, which might be slower than natively-compiled code (although this is debatable, these days); but I didn't have to write three different codepaths for each and every interoperation with the OS. I didn't have to worry about having a $HOME or a %HOME%. If I have to worry about packaging is just because I have to write about the ins and outs of a particular platform; in other circumstances I could have simply relied on python tools to do the right thing.

Python and QT could finally deliver the dream of portability that Java promised, if only we give them a sporting chance.

Labels: GeekDiary, maemo, meego, PyQt, python