Re: [gentoo-user] Question about difference between emerge --update world and emerge vigra

[Alan McKinnon <alan.mckinnon@gmail.com>]

On Thursday 25 September 2008 17:51:42 Hilco Wijbenga wrote:
> On Thu, Sep 25, 2008 at 03:27, Daniel Pielmeier
>
> <daniel.pielmeier@googlemail.com> wrote:
> > Also make sure you have a clean world file, which means if there is an
> > entry which is already needed by something else it should normally be
> > removed as this could cause problems.
>
> I can understand that if I have both package P and dependency D in
> world, and I remove P then depclean will not remove D. I assume that's
> not what you're talking about, though, as it's harmless and probably
> intended (since I listed D in world).
>
> Moreover, I would think this is quite common. You might have
> Java/Perl/Python/Ruby/* explicitely listed in world (because you write
> programs/scripts) and several packages that are either
> Java/Perl/Python/Ruby/* based or provide bindings. I *want* to be
> explicit here as I don't want Java/Perl/Python/Ruby/* removed should I
> remove those other packages.
>
> So what kind of problems are we talking about?

Most probably the "problem" that arises is when a mere dep cannot be removed 
by --depclean anymore because it is in world. It is a problem because of the 
unnecessary clutter it creates.

Also, sometimes deps come and go, and libs get split into two packages. Say 
you have libA which is a dep of some package Z. The dev sees that libA can 
benefit from USE flags in some way and this in turn benefits package Z. So 
libA gets split into libAa and libAb, both of which block the old libA. 
Package Z can install libAa or libAb or both depending on USE. If the user 
put the old libA in world (incorrectly), portage will not uninstall it to 
replace it with the new split libA. Instead it will display the blockers, 
which has to be resolved manually - and we all know how much mass hysteria 
and confusion blockers seem to cause amongst users...

This of course is the exact opposite of what you describe above

-- 
alan dot mckinnon at gmail dot com