It seems that MacPorts installs Python27 in /opt/local, but that MacPorts QGIS updates and uses the Apple Python27 in /Library. The result is that MacPorts additions to Python27 such as OpenCV don't work because they are added to the /opt/local Python27 whereas with QGIS installed all Python links point to the /Library Python27 so things like OpenCV can't be used. Has anyone found a way of keeping QGIS working while either 1. making it use the MacPorts Python27 at /opt/local, or 2. enabling MacPorts to add things to the /Library Python27?
The MacPorts people agree it's a problem, but are focussed on finding a 100% MacPorts solution (none yet after 5 months); they aren't interested in cooperating with the native QGIS or Apple Python. I've no response from the OpenCV people as to whether it can be linked to the /Library Python27. (Not being a Unix guru, I'd prefer to stay with MacPorts if that's possible.)