Re: [gentoo-dev] perl eclass review - EAPI=3 + new helper eclass

[Zac Medico <zmedico@gentoo.org>]

On 04/06/2010 07:22 AM, James Cloos wrote:
>>>>>> "ZM" == Zac Medico <zmedico@gentoo.org> writes:
> 
> ZM> You can configure eclass override behavior via eclass-overrides in
> ZM> /etc/portage/repos.conf, as documented in `man portage`.
> 
> ,----< From that manpage >
> | When using eclass-overrides, due to bug #276264, you must ensure that
> | your portage tree does not contain a metadata/cache/ directory.
> `----
> 
> Which translates into "eclass-orderrides are completely and entirely
> useless, so don't bother.

Well, it's roughly equivalent to the old default behavior (which you
apparently preferred). However, the issue is now complicated by the
fact that FEATURES=metadata-transfer is disabled by default, so when
portage goes to pull cache directly from metadata/cache/, it won't
be able to validate eclass changes since there are no eclass
timestamps saved inside metadata/cache/. FWIW, there was some
discussion about extending the cache format to improve
the validation mechanism for eclasses here:

http://archives.gentoo.org/gentoo-dev/msg_cfa80e33ee5fa6f854120ddfb9b468b3.xml

> Portage used to used to search for eclasses starting in the top overlay;
> it should not have changed.

Well, the biggest caveat to that behavior is that it tends to
invalidate metadata cache as reported in this bug:

  http://bugs.gentoo.org/show_bug.cgi?id=124041

I'd be happy to work on resolving issues with eclass-orderrides to
make it more usable. However, due to the need to regenerate metadata
cache, I don't think that this is something that can ever again be
enabled by default.
-- 
Thanks,
Zac