> On Fri, 18 March 2016, at 6:07 am, Alan McKinnon <alan.mckin...@gmail.com> > wrote: > > … > USE flags enable and disable features of software at compile-time. Take > for example a music player. Maybe it can store the metadata about your > music in flat files, in sqlite, in mysql or postgres. Now you must make > a choice where to put the flag. Maybe your music collection is HUGE and > postgres is the best fit. > > If you add it to make.conf it becomes global and every piece of software > that supports postgres will now be rebuilt to give postgres support. > Maybe you don't need or want that. > > A flag like that is best put into package.use where it applies only to > the package you list there. So postgres gets installed, the music player > gets support and your MTA does not.
To expand on this example, if `emerge -p` showed your music player had flags for mp3, mp4 and aac files, I would probably set those in /etc/make.conf, because I want all music and video players and converters to support these common file types. Stroller.
