[pacman-dev] Option Depency Ideas

Jeff 'codemac' Mickey jeff at archlinux.org
Fri Nov 2 18:02:39 EDT 2007

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 

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.

* 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 
    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.)
    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.
    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%

* 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 
    o Something else I haven't thought of.

* 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.

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.

    //  jeff
.: [ + carpe diem totus tuus + ] :.
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