He's not dead, he's resting
A Glimpse Into cave: Resolving Purges and Dependents
What happens when you upgrade a package, and the new version no longer uses a library that the old version did, and now nothing else uses that library either? In primitive distributions, you’re stuck with that library forever; in Gentoo and Exherbo the package manager will be able to tell you that the library is no longer used by any package in world. Until now, this has been a “do this once in a while, and try to remember what the heck all those things are” kind of affair. However, cave is cleverer:
And you can easily decide to take it as part of the upgrade process (safely, since cave supports mixing installs and uninstalls with dependencies etc):
This can also work with slots — however, doing so safely requires accurate slot information from packages, which sadly can’t take place in Gentoo until EAPI 4 is implemented in Portage.
Similarly, cave will tell you if you’re about to do something dangerous:
And if you decide to remove the packages that would be broken, rather than allow breakage to occur, you get to see more nice examples of purges:
This all works for downgrades too, as well as upgrades (although upgrades rarely break things, and when they do it’s time to yell at someone):
And finally, if you’re about to do something immensely stupid, you’ll be told:
All of this happens automatically, so there’s no need to remember to turn it on.