Re: [gentoo-user] Problem with revdep-rebuild

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

On Monday 16 August 2010 11:38:17 Dale wrote:
> Peter Humphrey wrote:
> > On Monday 16 August 2010 09:13:29 Dale wrote:
> >> Massimiliano Ziccardi wrote:
> >>> # equery belongs /usr/lib/libxfce4util.la<http://libxfce4util.la>
> >>> [ Searching for file(s) /usr/lib/libxfce4util.la
> >>> <http://libxfce4util.la>  in *... ]
> >>> #
> >>> "
> >> 
> >> Equery doesn't give any results because it is not installed.
> > 
> > If it weren't installed it wouldn't be able to announce what it was
> > searching for and where   :-)
> 
> Some new people think it knows where things come from even if it is not
> installed.  It can't do that so I posted that in case the person didn't
> know.  Then I posted a way to find out even if a package is not
> installed.  I didn't know about that website until someone pointed it
> out to me many ages ago.
> 
> It would be neat if it could do that tho.  Just have no idea how it
> could.  ;-)

It would have to consult a database of file->package mappings. For already 
installed packages, it simply looks in /var/ locally - an excellent high-
quality database of such already exists there :-)

For not already installed packages, it would have to look out on the 
intartubes for the site you mentioned or something similar. A portage dev 
would have to be batshit insane to even try that as the results are "fuzzy". 
There are filename collisions to deal with, plus the fact that you don't know 
what a package installs till someone builds it. And then there's the carnage 
caused by USE flags - my list of installed files for a package is likely 
different to yours.

A hallmark of portage is that it deals in definitive data - results are always 
exact, unambiguous and deterministic - especially deterministic.

Google for instance, is none of these things. Google results are "good 
enough". Mixing portage's view of data with google's view of data will break 
portage is many many horrible ways and make your life (as someone who helps 
others on this list) miserable - users *will* trust such a lookup tool to be 
definitive.

Which all goes to say you should resist the creation of any such lookup tool 
with every fibre of your being :-)


-- 
alan dot mckinnon at gmail dot com