The hard problems with Collections: (Was: tuxracer & chromium move to Extras_

[Tim Daly]

Alan,

>When you have too many repositories especially of critical stuff you
>end up in a gigantic dependancy disaster. That is one reason core has
>to be well controlled and why extras is defined in terms of building on
>core and extras only. This at least pulls the core libraries into a single
>place and form.

There aren't dozens of repositories. There are dozens (one per maintainer)
tag-lists feeding off the same repository. Core is just another taglist.
And core's taglist has one maintainer so we know who to shoot.

There may be a few repositories (e.g. some tag lists draw from a
binary proprietary location) but in general all a maintainer is trying
to do is satisfy his target audience (the computational mathematicians).

>Equally the original definition recognized people would want to do things
>that broke compatibility with core components and that users should be able
>to tell this would happen - Fedora Alternatives being the tag name we used
>for such packages. That might be as mundane as a gnome-libs variant with
>new features or as significant as using the FreeBSD kernel or Hurd as the
>core kernel.

Lets suppose there are two incompatible libraries, like libc6 and glibc.
A maintainer will have to choose one for his taglist. He'll also have to
ensure that all of the packages he chooses work with his lib choice. A
similar problem occurs with the choice of desktop, KDE vs GNOME. 

If we continue to use Core+Extras as concepts we'll have endless looping
discussions about why tuxracer must be in Core and even the kernel. It is
clear that the lagged-worldwide-free for all discussion is never going to
converge to consensus. At least the maintainer concept allows fedora to
support diverse communities that don't agree on "fundamentals".

>There does seem to be an O(N^lots) co-ordination requirement between main
>repositories and we must be careful of that. Maybe Conary will, once half
>of it has stopped being armwaved, solve that.

Repositories don't have to coordinate. Getting the distribution correct
and working is the maintainer's job. If the Computational Mathematics
taglist creates a bad build we know who to blame and who has to fix it.
If Core+Extras is broken there is nothing but finger pointing. 

Are you the Alan Cox of -ac fame? If so, surely you know about maintainers
in the kernel. 

Tim Daly
daly at idsi.net