Re: [gentoo-pms] Rephrasing *DEPEND

[Zac Medico]

On 06/12/2011 06:16 AM, Michał Górny wrote:
> On Sun, 12 Jun 2011 02:13:35 -0700
> Zac Medico <zmedico@g.o> wrote:
>
>> On 06/12/2011 01:18 AM, Ulrich Mueller wrote:
>>>>>>>> On Sun, 12 Jun 2011, Michał Górny wrote:
>>>
>>>> True. How about pkg_setup()? Shall we assume RDEPEND are there or
>>>> rely on @system only?
>>>
>>> IIUC, with Portage's breaking of dependency cycles there's no
>>> absolute guarantee that packages in RDEPEND will be available in
>>> pkg_*.
>>
>> It would be more accurate to say that it's guaranteed except for cases
>> in which circular dependencies make it impossible to guarantee.
>
> This or other words, this makes this an unreliable feature. So, right
> now, users can't assume anything specific about dependencies being
> installed in pkg_*?

In practice it's very reliable, although the specific behavior varies
depending on whether or not there are circular dependencies. So, it
would probably make sense to specify it like this:

(A) If there are no circular RDEPEND dependencies, then RDEPEND is
guaranteed to be satisfied.

(B) If there are circular RDEPEND dependencies, then RDEPEND is not
guaranteed to be satisfied.

> Doesn't this make it actually impossible to call
> the installed application in pkg_postinst()?

Only when case (B) applies. It may be possible to improve a situation
like this by making the circular dependency PDEPEND in one direction and
RDEPEND in the other:

  first RDEPENDs on second
  second PDEPENDs on first

This make it possible to guarantee case (A) for the first package, while
there is no such guarantee for the second package.
-- 
Thanks,
Zac