[Aptitude-devel] How to get two-stage install marking into the GUI?

[Daniel Burrows]

  Say I have two packages A and B.  A depends on B, but I the user want
to install both packages.  So I select A and B and mark them for
installation.  Some time later, I'm tired of A so I remove it.  Now what
happens?  At the moment, B gets removed.  I don't think we can do
anything about this (aside from exposing automatic status in the GUI) if
the user picks A and B separately.  But at the command-line, aptitude
handles this correctly when both are installed in the same shot:

$ aptitude install A B
 ... neither A nor B is marked as automatic ...

  The difference is that the command-line version installs packages in
two passes.  First it just turns on the "install" flag for everything
being installed (and the "remove" flag for everything being removed),
then it does a second pass where it asks apt to greedily resolve
dependencies (by setting the "autoinst" flag to true).  In the GUI,
this is made a bit more complicated by the fact that the install /
remove code is broken up and hidden behind virtual interfaces.

  Another place where you'd see this is when A depends on "C | B": with
a two-pass solution, only A and B end up being installed, but the
current code will also drag in C (because B isn't being installed when
A is selected).

  My current plan is to add a flag to the virtual interface indicating
whether to turn autoinst on, or perhaps make it more generic and have
it say whether we're in the first pass.  This feels a little hacky, but
I can't see any better resolution.  Does anyone see a better approach?

  I've attached my current solution as a patch.

    Thanks,
  Daniel
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