Currently KDE4 uses some abstraction layers such as Phonon (multimedia) and Solid (hardware, and stuff?). However, there is no package control layer. Although there is GetHotNewStuff2 and possible PackageKit integration (KPackageKit, etc) they are separate things (or so I assume...).

Should KDE4 have a more unified API for all kinds of package control, even for more advanced features (compile from source/git, etc)? discuss...

Use cases:

In some distributions there is this feature where if you try to play a multimedia file and you don't have the required codecs installed it does a small pop-up requesting permission to download those packages.

Now imagine something like that for the whole desktop:
- trying to install some ruby plasmoid would ask for permissions to fetch the necessary dependencies,
- selecting a new language for the spell checker would download and install any needed dictionaries,
- extracting an unknown compressed file would not cause an error but instead request permission for those formats (if available).
- etc.
It would also be nice if you could install things from source just as transparently as binaries (so it would fetch the build tools, do make install, or even extract from svn/git, etc).

I think PackageKit already serves that purpose, it is an abstraction layer for package managers. But stronger integration with packagekit would probably be a good idea. I assume your dependency and file-handler checking operations could be done using PackageKit, and if it can't it might be more efficient to improve packagekit rather than making an entirely new abstraction layer from scratch.

The problem with this is:

1) Distributions cannot integrate codec support fully ( even links ) due to legal issues ( DVD for instance )
2) Distributions have different package naming schemes.

Until these issues are resolved ( particularly issue 2 ) then this functionality will be difficult to implement

bcooksley wrote:1) Distributions cannot integrate codec support fully ( even links ) due to legal issues ( DVD for instance )

If the package for the codec isn't available the package manager should tell you that.

bcooksley wrote:2) Distributions have different package naming schemes.

Most package managers have a "provides" component for each package that tells you the programs and libraries that each package contains. I think it should be possible to use that to find the package that contains the library that provides the capability you are looking for, since the library names should be much more consistent than the packages that contain them (I think).