[arch-general] can you only test certain packages?

[Jim Pryor]

On Thu, May 20, 2010 at 06:04:42PM -0400, Daenyth Blank wrote:
> On Thu, May 20, 2010 at 18:05, Jeroen Op 't Eynde <jeroen at xprsyrslf.be> wrote:
> > There is a number 3.
> >
> > 3. Add [testing] and do a pacman -Sy package-you-like. It will install the
> > latest package from testing and its dependencies. Remove [testing] again and
> > you can go on using your non-testing system. I don't know if it is
> > fail-proof but it worked for me with xorg-server (to 1.8). When I'm doing a
> > pacman -Syu it just says that the packages installed are newer and therefore
> > doesn't update these certain packages.
> >
> This will only work if the package uses versioned depends, which is
> not always the case.

Also, suppose you want package Z from testing, which depends on libfoo
also in testing. And suppose that the libfoo update also mandated
rebuilding package W, which depends on libfoo and is also in testing. If
you just do "pacman -Sy Z", even if you *are* lucky enough to pull in
libfoo too (as you will if Z has a versioned depends on libfoo), you'll
probably still miss the update to W. So when you try to run the *old* W
still on your system, with the newer libfoo installed, boom.

That's why I said that the only reliably safe choice for binary installs
is to update everything in testing which is connected by any chain of
depends/requires relations to Z.

Of course, in many cases you'll get away with doing less. And if you
know what's in testing and why, you'll be able to better predict when
doing less will suffice. But I think the only reliably safe general
recipes are the two I stated.

-- 
Jim Pryor
profjim at jimpryor.net