On Tue, Mar 13, 2012 at 07:30:22AM +0000, Ciaran McCreesh wrote > EAPI is special. You need to know EAPI to be able to get the rest of > the metadata. > > > 2) Any potential ebuild processor that's incapable of looking for > > regex "^EAPI=" in a textfile, amd parsing the numbers that follow, > > has no business being used to process ebuilds. > > That doesn't get you the EAPI.
On Tue, Mar 13, 2012 at 12:03:34AM -0700, Brian Harring wrote > Perfectly valid, if stupid, bash: > > EAPI=3 > EAPI=4 > > Which is the PM to choose? Because if your answer is "the first", > then you need to keep in mind that any following code (including > eclasses that test eapi) will be seeing the second during sourcing. > Nice little gotcha, that one. > > I'm aware people have suggested "make EAPI readonly" to try and deal > w/ this; that however means it'll break any PM that uses eval for > loading the ebuild, and means that every ebuild sourcing for phase > running will throw a complaint about EAPI being readonly. > > I don't hugely expect PMs to screw up the ordering of which to chose, > although it exists; trying to ban secondary settings is also an > approach... but all of it points to the fact it's a fricking hack and > isn't really worth doing. I'm answering Ciaran's and Brian's posts together, because the answer is the same for both... namely, we need a 2-pass processor, regardless of whether it's bash/perl/python/whatever. Pass 1 checks for syntax errors and retrieves "special" variables, answering Ciaran's concern. Today, it's EAPI. In future, there may be others. Pass 2 does the build, assuming no errors detected in pass 1. Under the heading of "syntax errors", I would include multiple EAPI declarations. My response to Brian is that portage should not try to outguess or fix or override an obviously broken ebuild. It should return an error message (in this case "Multiple EAPI declarations not allowed") and then halt. It is the ebuild-writer's job to come up with a syntactically correct ebuild. -- Walter Dnes <waltd...@waltdnes.org>
