Gentoo Archives: gentoo-pms

From: Ciaran McCreesh <ciaran.mccreesh@××××××××××.com>
To: gentoo-pms@l.g.o
Subject: Re: [gentoo-pms] Do we want an EAPI 5?
Date: Fri, 01 Jul 2011 06:15:32
Message-Id: 20110701071238.17dee2b8@googlemail.com
In Reply to: Re: [gentoo-pms] Do we want an EAPI 5? by Sebastian Luther
1 On Thu, 30 Jun 2011 20:48:46 +0200
2 Sebastian Luther <SebastianLuther@×××.de> wrote:
3 > > Portage's behaviour is already broken there -- think what happens
4 > > when ebuilds get removed.
5 >
6 > I know. I'm not opposed to this change, but the needed work flow
7 > change for ebuild devs has to be communicated.
8
9 Shouldn't be a workflow change. It's already policy to do a revbump if
10 dependencies change.
11
12 > >> Could you please give a summary (or point me to one) of the
13 > >> discussion about :=/:*?
14 > >
15 > > See the original EAPI 3 discussion. It's all there.
16 > >
17 > Yeah, the whole discussion is there, but not a summary. I don't have
18 > the time to wade through all these mails.
19
20 Part of the reason EAPI 3 dragged on for so long was that rather than
21 reading the discussion, people would say "I've not read the entire
22 thread, but it seems to me that ...", and then the entire discussion
23 would have to be repeated all over again.
24
25 If you're just looking for a summary, not details: say a user has
26 cat/dep:1, cat/dep:2 and cat/dep:3 installed, and wants to uninstall
27 cat/dep:1 and cat/dep:2. Say there's cat/pkg installed which has a dep
28 upon cat/dep. Then there's no way for the package mangler to know
29 which cat/dep slots are still 'needed', and which can be safely
30 removed. Thus, to be safe, it has to assume that all three slots might
31 be needed.
32
33 Nearly all packages that dep upon a slotted dependent have one of two
34 behaviours: they're ok with any slot that matches the rest of the spec
35 (including switching at runtime), or they need the best slot that was
36 present at install time. The former is :*, the latter :=.
37
38 There are a few perverse cases that don't fit these. Those need special
39 fancy handling, and they're sufficiently fiddly that we shouldn't be
40 holding up solving the large number easy cases to deal with one or two
41 weird packages.
42
43 > Isn't it desirable that different PMs handle the "no operator" case in
44 > the same way (independently of the question of having one or both
45 > operators available)?
46
47 The problem is that every way of handling the "no operator" case is
48 wrong for many real situations. You can assume either "any slot" or
49 "best slot", both of which will allow packages to be removed unsafely,
50 or you can assume "all slots", which is excessively paranoid for many
51 packages.
52
53 --
54 Ciaran McCreesh

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Re: [gentoo-pms] Do we want an EAPI 5? Sebastian Luther <SebastianLuther@×××.de>