Displaying suggested packages about appstream

[ximion]

Short version: We discussed that in-depth about a year ago, and a suggests/enhances/recommends system will not happen.

Long version: We have addons to indicate extensions to enhance a certain software component. If a software requires certain stuff to be present, or recommends it to be there, it should depend on it, bundle it, or let the package manager handle the details. AppStream is no place for this packaging logic.

If an application finds out that it needs a specific addon to perform a task, it can request any AppStream-capable software center to prompt the user to install a missing module, or just use AppStream directly to install the piece.

The package manager should manage the complicated dependencies and allow the fine-grained verbose mode of handling dependencies, including very technical bits. AppStream is not set to replicate and duplicate the logic and metadata a package manager provides.

It could be that you want some kind of reverse-addon logic here, so something that allows an app to suggest other apps which go well with it (e.g. "if user has KDevelop, they might also want cmake").
This logic is already defined and available in AppStream, both for upstream projects to define (type="upstream") and machines to select (type="heuristic"). See https://www.freedesktop.org/software/appstream/docs/chap-Metadata.html#tag-suggests and https://www.freedesktop.org/software/appstream/docs/chap-CollectionData.html#tag-ct-suggests