Re: [gentoo-dev] RFD: EAPI specification in ebuilds

[David Leverton <levertond@googlemail.com>]

On 7 March 2012 21:07, Alexis Ballier <aballier@gentoo.org> wrote:
> As i understand it, $PM will need to try the regexp tingy on any ebuild
> anyway, guess the EAPI then source the ebuild with the right sourcer
> to get the real EAPI and compare it.

Not exactly... the idea with proposal 2) is that the header comment
becomes the One True Way to set the EAPI, so it wouldn't be "guessing"
as such, and ebuilds wouldn't be allowed to change it during sourcing
any more than they can redefine PV or the like.  As mentioned, 2b)
still risks a mismatch between the header and the assignment, but
hopefully that would be temporary and the assignments could be dropped
eventually.  (And I'd suggest that the header EAPI is still considered
authoritative if present - the mismatch check should probably be a
hard error, or if not it should generate a warning and use the header
value.  There should be minimal if any risk of this changing behaviour
for any existing ebuild, since existing ebuilds almost certainly won't
match the chosen header syntax.)

As for my opinion, I would prefer 2a), or 2b) as a second choice.
IMHO it's much simpler and cleaner to come up with a strict,
well-defined header format than to try and work within (an arbitrarily
restricted version of) bash syntax.