[pacman-dev] Option Depency Ideas

[Roman Kyrylych]

2007/11/3, Jeff 'codemac' Mickey <jeff at archlinux.org>:
> Hello all.
>
> I figure I should start flexing my "zomg coding" muscles a little more for
> the benefit of arch.  What interests me the most right now is optional
> dependencies.  In my local git tree I have added pactest support for
> testing option dependencies, but I only have one joke of a pactest that
> checks.
>
> Thanks to Dan, a lot of the work that I really would have a harder time
> getting right has all ready been done, in adding the right lines to
> makepkg, libalpm, and pacman so that the optional dependencies are recorded
> in the db.  Right now they are only recognized as simple strings, not as
> packages with dependency resolution or any of that fun stuff (correct me if
> I'm wrong here Dan).
>
> The next steps appear to be the following:
>
> * makepkg should recognize the 'pkg:reason for package being option' format
>   I've seen thrown around.

Yes.

>
> * When a package is installed with optional dependencies, we can do a
>   couple different things.
>     o Ask the user right there with the "Install package foo for xyz
>       support?"

Yes.

>     o Ask the user to explicitly install the optional deps themselves (I
>       don't think this is good at all.  This wouldn't keep them listed as
>       "installed as a dependency" and we could just have echo statements in
>       the .install then.)

Could be useful with --noconfirm.

>     o Check for some kind of /etc/pacman.conf var that lists what packages
>       users don't mind having as optional dependencies, otherwise ask them
>       to install them.

Nah, that will turn into Gentoo's USE flags.

>     o Something else I haven't thought of.
>
> * When an optional dependency is installed through one of the 3 ways listed
>   above, we need to install it as a dependency, and add it to %DEPENDS%,
>   leave it in %OPTDEPENDS%, and not put it in %REQUIREDBY%

Leave it in %OPTDEPENDS% and do not put it in %REQUIREDBY% and %DEPENDS%.

>
> * When an optional dependency is uninstalled that was only ever installed
>   as a dependency, we can do several things.
>     o We warn the user that they are losing functionality, and remove it
>       from the %DEPENDS% array in the parent.
>     o We let pacman handle it like it does dependcies, this is what we get
>       when we add the optional dependency to just %DEPENDS% and not
>       %REQUIREDBY%
>     o Something else I haven't thought of.

IMO Pacman should handle optdepends not in the same way as depends,
so it should be removed from %OPTDEPENDS% array of there parent.
About %REQUIREDBY% - probably there should be %OPTREQUIREDBY% ?

>
> * When a package with optional dependencies is removed, it should also
>   remove all other packages that have been moved into %DEPENDS% haven't
>   been explicitly installed.  I believe this is funcitonality that we get
>   by adding it to the %DEPENDS% array anyways.

Then any optdepends that doesn't have other packages in %REQUIREDBY%
and %OPTREQUIREDBY% should be asked for removal.

>
> I just wanted to get these thoughts out there.  I thought I was just going
> to implement basic -Qi functionality and then address these.. but Dan is a
> beast and jumped the gun on me.
>
> I would like to hear all of your thoughts on the above ideas, and let's
> flesh out what action we'd like to see pacman take based on these
> difference scenarios.
>

References:
  http://bugs.archlinux.org/task/4845#comment10357
  http://archlinux.org/pipermail/pacman-dev/2006-October/005999.html
  http://archlinux.org/pipermail/pacman-dev/2007-September/009426.html

-- 
Roman Kyrylych (Роман Кирилич)