On Wed, Dec 09, 2009 at 07:19:22PM +0200, Eugene V. Lyubimkin wrote:
> > We have to tell dpkg remove this package/install this package, and not
> > "bring us to the following state". Thus, I think that receiving those
> > actions from the solver makes things easier, and not more complicated.
> No. Consider the variant when some package is in the stage 'unpacked'. You'll
> have to pass all the installed packages' states before scheduling actions
> anyway. And the external resolver has nothing to do with dpkg.
Well, even in that case, you _eventually_ need to split up the universe
into actions/transactions/... or whatever the low-level package manager
calls them. For instance, in the full state you will always have some
(usually a lot) of the currently installed packages and you will
eventually need to recognize that you will not need to do anyhow with
them, because they are good as they are.
So it is definitely true that someone/somewhere/at some point needs to
compute the diff between the new status returned by the dependency
solver and the former status currently known by the high-level package
manager.
That's to say that I'm more or less convinced by Julian's arguments
about a "diff like" format, as long as actions are only install and
remove (as discussed in a separate sub-thread, already ack-ed) and on
specific packages. How to group/order such actions is a matter that the
high-level package manager will need to decide by itself.
Now, Eugene, would that make things harder for cupt?
Otherwise stated, would you accept to "outsource" the computation of the
diff to the external solver?
If not, I can support a kind of protocol that I anticipated already: in
the "preamble: " of the request to the external solver we add a
"requested-format" or something such to choose among "new state" and
"diff" styles.
Cheers.
--
Stefano Zacchiroli -o- PhD in Computer Science \ PostDoc @ Univ. Paris 7
zack@{upsilon.cc,pps.jussieu.fr,debian.org} -<>- http://upsilon.cc/zack/
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