understanding relations between binary packages

[Ralf Treinen <treinen%pps.univ-paris-diderot.fr@localhost>]

Hello,

I am trying to apply tools from the EDOS and Mancoosi projects to the analysis
of relations between packages in pkgsrc. In the past, we have done this
successfully for binary distributions like Debian, Mandriva, and OSGi bundles.
After my presentation of our tools at pkgsrcCon 2013 (slides: [1]) I started
to look at the pkgsrc format for binary packages in order to understand how
we can apply our tools to pkgsrc BINARY packages.

Hubert Feyrer pointed me to [2] as a starting point. However, I have some
problems understanding the precise semantics of REQUESTS and PROVIDES as these
seem not to be documented (AFAICS). Is the following interpretation correct:

I can install a binary package iff:
1) all its DEPENDS are installed (yes, I know about alternatives in {..})
2) for every library that appears in REQUIRES, a package that PROVIDEs this
   library is installed.
3) None of it CONFLICTS is installed 

Any help would be appreciated. As you might have guessed I am not myself a
pkgsrc user.

Cheers -Ralf.

[1] http://www.pps.univ-paris-diderot.fr/~treinen/publi/slides/pkgsrccon2013.pdf
[2] ftp://ftp.netbsd.org/pub/pkgsrc/packages/NetBSD/i386/6.0/All/pkg_summary.gz
-- 
Ralf Treinen
Laboratoire Preuves, Programmes et Systèmes
Université Paris Diderot, Paris, France.
http://www.pps.univ-paris-diderot.fr/~treinen/
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