Some previous problems with the Python 2.5 installed by MacPorts made me think it could be some dependency with the native library called by the Python module; that is what I think that was also happening with py25-hashlib, which caused an error about being unable to find _md5 or some such, and which got fixed by uninstalling MacPorts' openssl 0.9.8g and installing 0.9.8h (and reinstalling py25-hashlib afterwards).
(and I say "think" because maybe that problem was unrelated to openssl, and in fact could be related to python_select, which I maybe had or had not run. Read on for more on that. Anyway, there was also some report online of problems between Pythons' hashlib and openssl because of the exact version used, and mentioned Python being a bit fragile in that respect — although it didn't say if that was because of a not-too-robust build/installation process, or because of Python's design.)
But here the problem was different. Reinstalling Qt 4 and PyQt4 did not help. After some googling, I found someone (thanks jherm) with the same problem... and who in some chat log is told by some MacPorts developer (?) the anticlimactical solution: follow the instructions at the end of the installation of MacPorts' Python 2.5. That is,
$ sudo port install python_select $ sudo python_select python25Looks like this has to be run "to complete the installation". Sheesh. So that was a hard requisite? Shouldn't that have been told pretty explicitly then? (I'm seeing a number of reports about this kind of problem, so yes, I think the warning should be quite more explicit... I should start some bug reporting, I guess.)
So the problem seems to be that PyQt4 uses Python in its build process, assuming that it is the same in which it will be run afterwards. But in my case I had not run python_select after installing MacPorts' python25, because it seemed optional, and I didn't want to use it as the default… so PyQt4 was building against OS X's default Python.
So, after python_select, PyQt4 builds OK. It doesn't manage to get fully installed, mind you, but I guess that this other problem has more to do with MacPorts. Anyway, with a
$ sudo port -f install py25-pyqt4it finally gets installed (although something remains to be finished, like the MacPorts' database getting properly updated; that can be checked with -d).
All of this was in the process to try to make Anki run from source. I was trying to test some modifications before sending the patches, but making sense out of the tortuous source and setting up the environment have required much more time than expected. I should be studying Polish instead! The exam is coming! :P