Re: [gentoo-dev] Reliance upon || ( use? ( ) ) behaviour

[Paul de Vrieze]

On Saturday 24 February 2007, Jason Stubbs wrote:
> On Saturday 24 February 2007 12:34, Ciaran McCreesh wrote:
> > On Sat, 24 Feb 2007 12:27:35 +0900 Jason Stubbs <jstubbs@g.o>
> >
> > wrote:
> > | For the 14 cases you mentioned that were making a mistake, they
> > | probably can be rewritten so as to force an install of the first
> > | matching package, but when that isn't what is wanted it becomes a bit
> > | of a headache.
> >
> > That should *always* be what's wanted. Packages should only alter
> > dependencies / build parameters based upon USE flags, not based upon
> > what else happens to be installed.
>
> Okay, I must be missing something here. If package foo can work with either
> bar or baz equily as well but not both, why should it force an artificial
> preference? Also, if packages should not specify dependencies based on
> what is installed, the semantics of || ( ) would need to be changed such
> that the first non-masked packages is always installed.
>
> The only reason I can see for the above is to be able to have non-broken
> binary packages. However, that can be addressed by replacing *DEPEND in
> binary packages with their resolved forms.

That is something that needs to be done anyway. In general a binary package 
has SLOT dependencies on the libraries it uses. It is also unwise to use it 
with an older version of a dependency.

So

RDEPEND=">=libfoo-1.2"

Against libfoo-1.3.5(SLOT=3) (where 1.4(SLOT=4) exists too

becomes something like:
BDEPEND="&& ( >=libfoo-1.3.5 libfoo[SLOT=3] )

I know this is not valid syntax, but it is just to convey the idea.

Paul



-- 
Paul de Vrieze
Gentoo Developer
Mail: pauldv@g.o
Homepage: http://www.devrieze.net