Unpacker eclass has been in the tree since 2012-02-01 (see bug #399019). This eclass makes it easy to get consistent behaviour across different package managers (see bug #384147 for inconsistency example). It also allows to add support for new formats in a day (see bug #432214). Suggestion: In some future EAPI unpack should be replaced by unpacker from unpacker.eclass.
How would this work? Package mangler code can't require eclasses.
Bug #380391 is more realistic IMO, but people will never approve this. Or just have a Gentoo policy to always inherit some kind of common eclass.
(In reply to comment #2) or inherit it whenever you use .deb or a new format. if you want to enforce the .deb part, you could make it into a repoman check.
In the current form, this can't work. Since there's no new replies from OP, I'm closing it as CANTFIX.
@mgorny: OP ?
(In reply to comment #5) > @mgorny: OP ? Original Poster, so that would be you ;).
Due to comment #1 this is CANTFIX.