[Interest] Qt 5.3 vs Qt 5.4 (etc)

[René J.V. Bertin]

On Monday January 12 2015 14:10:12 Andreas Pakulat wrote:
Hi,

> not sure wether it was intentional to reply only to me, but I'm replying in
> private too just in case.

No, it wasn't, so I'm replying publicly.

> > I must say I haven't yet tried to build all the Qt5 packages, so I cannot
> > even be sure if 5.2 and 5.3 are packaged exactly the same way. It would
> > stand to reason that Qt 5.x packages have tighter dependencies among
> > themselves, I suppose?
> >
> 
> Yes, package changes especially in the earlier versions of a new major qt
> release are of course something which may have influences on other packages
> and hence dependencies might be stricter.
> 
> I haven't looked at the Qt5 packages in debian too much yet since I don't
> use qt5 most of the time, but I see for example libqt5qml5 having a rather
> loose dependency on libqt5network5 (>= 5.0.2). So its likely that the
> debian developers have ways (as the page posted by Alejandro) to figure out
> what the exact needed ABI is for a given qt module and depend on the first

FWIW, Debian packaging allows to create a list of expected symbols for each or some of the created packages.

> version where this ABI was introduced. In other cases like the opengl
> module dependencies are tighter to the core/gui/widgets module, presumably
> because more ABI is used and hence its affected more by changes in that API
> (the modules are more tightly integrated with each other).

Yes, that must be it. OpenGL isn't the best example though; it's in qtbase, meaning below the level where the "split-up" occurs. At least in Debian/Ubuntu.
I created a PPA for qtbase 5.4, and could only install 3-5 packages from there if I didn't want to uninstall way too many packages, and of course that broke Qt5 function. Fortunately I had created a new PPA for this and there's ppa-purge to roll-back and reinstall packages that were updated after adding that PPA :)

R.