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DPM § 7.2 and proposal for Pre-Recommends



Hey list,

Guillem and I were discussing a design issue I was having today with an
upstream package. There may be various workarounds, but I think the
scenario I am confronted with may have presented itself to others. I
believe I may have a generalized solution I would like to propose for
peer review.

Currently under DPM § 7.2 packages may contain a Recommends stanza in
their d/control files:

   "This declares a strong, but not absolute, dependency. The
   Recommends field should list packages that would be found together
   with this one in all but unusual installations."

Consider the scenario where there may be a package A that recommends a
package B (say, a local database instance instead of a remote one).
Perhaps A is a system service that does not require B. But if B is
configured A may need to do something during its postinst hook as a
convenience to leverage B immediately.

The problem, however, is that if B was selected for installation at the
same time as A then there is no guarantee that B will be configured
prior to A.

I propose a Pre-Recommends stanza. It would be a blend of Depends and
Recommends such that anything listed in Pre-Recommends that is selected
for installation must be configured first. In other words it allows for
ordering constraints on a soft dependency.

Thoughts?

-- 
Kip Warner | Senior Software Engineer
OpenPGP signed/encrypted mail preferred
https://www.thevertigo.com

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