On Thu, Feb 01, 2018 at 03:36:28PM -0500, Eli Schwartz via aur-general wrote:
[...] Well, lots of people already do this, via urlwatch or pkgbuild-urlwatch. I think the idea was supposed to be, finding a way to do this without introducing complex tricks that need to be manually added to the PKGBUILD and then fragilely parsed.
-- Eli Schwartz Bug Wrangler and Trusted User
Repology has taken the approach of comparing the versions in various repositories (as well as some other sources like PyPi).
Their parser collection could maybe be a source of inspiration.