EAPI 3: A Preview

Gentoo is shuffling its way towards EAPI 3. The details haven’t been worked out yet, but there’s a provisional list of things likely to show up that’s mostly been agreed upon. This post will provide a summary; when EAPI 3′s finalised, I’ll do a series of posts with full descriptions as I did for EAPI 2. PMS will remain the definitive definition; I’ve put together a a draft branch (I’ll be rebasing this, so don’t base work off it if you don’t know how to deal with that).

Everything on this list is subject to removal, arbitrary change or nuking from orbit. We’re looking for a finalisation reasonably soon, so if it turns out Portage is unable to support any of these, they’ll be dropped rather than holding the EAPI up.

EAPI 3 will be defined in terms of differences to EAPI 2. These differences may include:

• pkg_pretend support. This will let ebuilds signal a lot more errors at pretend-time, rather than midway through an install of a hundred packages that you’ve left running overnight. This feature is already in exheres-0.
• Slot operator dependencies. This will let ebuilds specify what to do when they depend upon a package that has multiple slots available — using :* deps will mean “I can use any slot, and it can change at runtime”, whilst := means “I need the best slot that was there at compile time”. This feature is already in exheres-0 and kdebuild-1.
• Use dependency defaults. With EAPI 2 use dependencies, it’s illegal to reference a flag in another package unless that package has that flag in IUSE. With use dependency defaults, you’ll be able to use foo/bar[flag(+)] and foo/bar[flag(-)] to mean “pretend it’s enabled (disabled) if it’s not present”. This feature is already in exheres-0.
• DEFINED_PHASES and PROPERTIES will become mandatory (they’re currently optional). This won’t have any effect for users (although without the former, pkg_pretend would be slooooow).
• There’s going to be a default src_install of some kind. Details are yet to be entirely worked out.
• Ebuilds will be able to tell the package manager that it’s ok or not ok to compress certain documentation things using the new docompress function.
• dodoc will have a -r, for recursively installing directories.
• doins will support symlinks properly.
• || ( use? ( ... ) ) will be banned.
• dohard and dosed will be banned. (Maybe. This one’s still under discussion.)
• New doexample and doinclude functions. (Again, maybe. Quite a few people think these’re icky and unnecessary.)
• unpack will support a few new extensions, probably xz, tar.xz and maybe xpi.
• econf will pass --disable-dependency-tracking --enable-fast-install. This is already done for exheres-0.
• pkg_info will be usable on uninstalled packages too. This is already in exheres-0 and kdebuild-1.
• USE and friends will no longer contain arbitrary extra values. (Possibly. Not sure Portage will have this one done in time.)
• AA and KV will be removed.
• New REPLACED_BY_VERSION and REPLACING_VERSIONS variables, to let packages work out whether they’re upgrading / downgrading / reinstalling. exheres-0 has a more sophisticated version.
• The automatic S to WORKDIR fallback will no longer happen under certain conditions. exheres-0 already has this.
• unpack will consider unrecognised suffixes an error unless --if-compressed is specified, and the default src_unpack will pass this. exheres-0 already has this. (Maybe. Not everyone’s seen the light on this one yet.)
• The automagic RDEPEND=DEPEND ick will be gone.
• Utilities will die on failure unless prefixed by nonfatal. exheres-0 already has this.

Unless, of course, something completely different happens.

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