From: Massimiliano Mirra <list@...>
Date: 2002-09-17T22:56:34+09:00
Subject: Re: Dependency "trees" - suggestions?

On Tue, Sep 17, 2002 at 10:36:36PM +0900, Paul Brannan wrote:
> On Tue, Sep 17, 2002 at 10:30:30AM +0900, Massimiliano Mirra wrote:
> > Yes.  This means that for each node I add, the entire graph has to be
> > traversed again looking checking for cycles.
> 
> OIC, you aren't interested in protecting against a corrupted database;
> you just want to prevent the user from specifying a cyclic
> dependency.

Actually, the user just specifies the starting package.  rpkg looks at
the package names in its `Depends:' field, queries the database for
them, looks in turn at the packages in their `Depends:' fields... and
so on, until it gets to the `leaf' packages (those who don't depend on
any).

There is so much information to keep track of, that it's possible for
a package's maintainer to specify a dependency that in some cases
causes a cycle.  That happens seldom in Debian (I've only seen it
twice or thrice in more than a year, and Debian has over 7000
packages), but it's not impossible, plus we'll all be novices in
distribution management. :-)



Massimiliano