[RFC] Software management API proposal

[imobachgs]

This PR implements a tentative API for software management. It is still a WIP, but it serves as an indication of the direction we are following.

• The entry point to the API is the SoftwareManager class, which offers an API to initialize the software stack, query for "resolvables" (packages and products), etc.
• Potentially, it supports multiple backends. Support for libzypp is implemented as any other backend.
• Classes like Package or Product should be backend-agnostic (not implemented yet).
• It implements a rich query API (see SoftwareSearch), although it is far from being finished.

An example

require "y2packager/software_manager"
require "y2packager/libzypp_backend"

manager = Y2Packager::SoftwareManager.new
manager.probe # Initialize the software stack
query = manager.search.with(kind: :product)
query.each do |product|
  puts product.name
end

# you can extend the query later
query.with(name: "SLES")
query.first&.name #=> "SLES"

Pending

• [ ] PackageSearch:
  • [ ] Load all the attributes, including custom ones. See the existing Y2Packager::Resolvable class.
  • [ ] Allow searching for multiple states.
  • [ ] Offer a better way to define conditions (?)
• [ ] Ad-hoc installation of packages/products
• [ ] Implement the SoftwareProposal class and the corresponding SoftwareManager#commit method.

[coveralls]

Coverage increased (+0.01%) to 41.23% when pulling 6af7e8b8b5d165619df2a4d9749b06f06be38dd7 on packager-ng-model into 25a8bb990c4b9e81d2af2c4a699288dd95f90900 on master.

[imobachgs]

We are following a more conservative approach.