On Sun, 16 Oct 2011 10:46:33 +0300 Eugene V. Lyubimkin wrote:

> On 2011-10-15 17:27, James Vega wrote:
> > Well, I currently don't have any libclutter-1.0-0 versions installed,
> > which is why the pin is for any version.  Also, I tried changing the
> > Pin-Priority to -2000 and that didn't change the outcome any.
> 
> Even -2000 is too big for this case (using the current system).
> Something like -20000 would probably work for most cases. But,
> obviously, editing pin priorities by hand after tools is not a solution
> at all.

Hi Eugene!   :-)

I can change the default Pin-Priority that apt-listbugs uses to prevent
the installation of any version of a package from -40 to -20000 , if
this can work for most cases with Cupt...
For Apt/Aptitude, any negative Pin-Priority is equivalent: the
apt_preferences(5) man page says that any P < 0 will prevent the
version from being installed.

> 
> > Hmm, I would find that unfortunate in this instance since apt-listbugs
> > is a very useful tool.
> 
> Indeed it is. Once/if the Cupt-specific system is rolled out, I hope
> it's possible to generate a snippet for Cupt as well.
> 
> Hi Francesco, would it be possible for apt-listbugs also place a snippet
> like, say,
> 
> -8<-
> Comment: <explanation of reason>
> [ more comment lines ]
> Package: <package name>
> Version: 1.2-1 1.3-4 (optional line, if concerns only specific versions) 
> Priority: -<number>
> ->8-
> 
> to, say a file /etc/cupt/version-priorities.d/apt-listbugs, given that a
> proper wishlist bug with technical details is filed a couple of months
> later?

Mmmmmh...
This looks like much more work than it would appear at a first
glance...   :-(

Currently, apt-listbugs has to perform several actions
with /etc/apt/preferences: not only it has to generate one stanza
for /etc/apt/preferences, when the user requests a package to be pinned,
but also:

 (A) it has to check whether a given package is already pinned in
     /etc/apt/preferences, in order to make the interactive command-menu
     work correctly

 (B) it has to parse /etc/apt/preferences in a cron.daily job (see
     /etc/cron.daily/apt-listbugs and
     /usr/share/apt-listbugs/aptcleanup) and drop stanzas if the
     corresponding bugs are fixed in the unpinned candidate version

 (C) maybe it has to do something else that I don't remember now...

I am under the impression that adding support for a distinct pinning
mechanism would require adding a lot of code, if at all possible.
As far as (B) is concerned, I think an entirely new additional and
independent check would need to be implemented
for /etc/cupt/version-priorities.d/apt-listbugs
This would not make me happy!
But what about (A)? What if a package is pinned for Apt, but not for
Cupt? Or vice-versa? Please remember that configuration files may be
edited by hand by the (super-)user, hence it may always happen that a
package is pinned for one package manager, but not for the other one...

In conclusion, I am not happy to hear that you are considering the idea
to make Cupt use a distinct pinning mechanism, and stop sharing pinning
preferences with Apt/Aptitude.
I think it would be much better, if Cupt could continue using the same
pinning preferences as Apt/Aptitude (that is to say the ones found
in /etc/apt/preferences). I can understand that Cupt implements a
different resolver, and has therefore different needs, but, IMHO, it
should try hard to re-use the settings found in /etc/apt/preferences .

At least, this is what I think about this issue.
I hope my contribution to the discussion helps.

Bye.

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