/[gentoo]/xml/htdocs/proj/en/glep/glep-0021.txt
Gentoo

Contents of /xml/htdocs/proj/en/glep/glep-0021.txt

Parent Directory Parent Directory | Revision Log Revision Log


Revision 1.4 - (show annotations) (download)
Sat Apr 21 03:13:16 2007 UTC (7 years, 7 months ago) by antarus
Branch: MAIN
Changes since 1.3: +3 -3 lines
File MIME type: text/plain
Two gleps are Rejected, a bunch moving from Draft -> Deferred since no one is working on them

1 GLEP: 21
2 Title: User-defined Package Sets
3 Version: $Revision: 1.3 $
4 Last-Modified: $Date: 2006/09/04 03:06:32 $
5 Author: Tal Peer <coredumb@gentoo.org>,
6 Alec Warner <antarus@gentoo.org>
7 Status: Deferred
8 Type: Standards Track
9 Discussed-To: gentoo-portage-dev@lists.gentoo.org
10 Content-Type: text/x-rst
11 Created: 22-Feb-2004
12 Post-History: 6-Mar-2004, 3-Sep-2006
13
14 Status
15 ======
16
17 Taken over by antarus.
18
19
20 Abstract
21 ========
22
23 In Portage, package sets (formerly known as 'classes' or 'targets')
24 are mere groups of packages, grouped together to allow easier updating
25 and handling of them. Currently it is impossible to define sets further
26 than the two default ones: "system" and "world".
27
28 Motivation
29 ==========
30
31 Over the months, quite a few requests for user-defined sets were
32 made by users and developers, either by posting bugs, messages to
33 mailing lists or on IRC. Usually the response is that this is an
34 awesome idea, but no one ever took the time to actually define it
35 properly and implement it.
36
37 This document offers a specification for the implementation of
38 user-defined sets using configuration files similar to the current
39 world/system sets use.
40
41 Specification
42 =============
43
44 The proposed implementation uses a one file per set approach, meaning
45 each package set is defined in a single file. All set definition files
46 will reside in a directory ``/etc/portage/sets/`` and each set's name
47 will be its file name. Therefore, if one defines a set in
48 /etc/portage/sets/foo-set, the set name will be 'foo-set'. Usual
49 package naming rules [#NAME-RULES]_ also apply to sets.
50
51 As it is impossible to create two or more files with identical names
52 in the same directory, a theoretic conflict between two different sets
53 sharing the same name is impossible. However, users may define a
54 package set whose name conflicts with one more or packages (for ambiguity
55 resolution, see below).
56
57 Syntax for the package list file is the same as the world file syntax,
58 as described in the Portage manpage [#PORTAGE-MANPAGE]_, with one
59 addition: sets may not be 'inherited' by other sets, only packages may
60 be listed. There is no limitation to the number of packages in a set
61 or to the number of sets a package may belong to.
62
63 Using User-defined Sets With Emerge
64 --------------------------------------
65
66 The user-defined sets will be available either directly or using
67 the --package-set option, As in::
68
69 # Basically the same:
70 emerge foo-set
71 emerge --package-set foo-set
72
73 The --package-set option is introduced to bypass ambiguities, as
74 illustrated in the next example::
75
76 emerge foo # Where foo is both a set and a one or more
77 # existing packages. This will cause emerge to show
78 # the ambiguity, ask us to be more
79 # specific, and stop.
80
81 emerge --package-set foo # So we specify that what we actually
82 # meant was the package set.
83
84 emerge cat-bar/foo # Or we specify the exact package name.
85
86 When running emerge with the --pretend option, sets will be
87 expanded to the packages they are comprised off in the output, as with
88 the current system-defined sets.
89
90 Only one set may be passed to portage at time, and sets can not
91 be mixed with ordinary packages. Thus, the following snippets are
92 all invalid and will result in an error (assuming ``foo-set`` and
93 ``bar-set`` are defined as sets)::
94
95 emerge foo-set glibc
96 emerge bar-set system
97 emerge world foo-set gcc
98
99 Compatibility With Other Portage Features
100 -----------------------------------------
101
102 * Dependencies:
103 Package sets (both system-defined and user-defined) may not be
104 depended on by ordinary packages and eclasses.
105
106 * package.mask:
107 Masking a package set through the ``package.mask`` file is forbidden.
108 In order to 'mask' a package set, one should move it away from the
109 sets directory.
110
111 * package.use:
112 USE flags may not be defined for sets in the ``package.use`` file.
113
114 Implementation
115 ==============
116
117 The implementation of the package sets concept in Portage should be
118 mostly done in portage.py, and only the interface parts should be
119 added to emerge itself, to keep the separation between interface and
120 logic.
121
122 The amount of work needed for implementation is not trivial, but not
123 huge either.
124
125 Rationale
126 =========
127
128 The one file per set approach makes it easy to list the sets which are
129 defined on a system by just listing the ``/etc/portage/sets``
130 directory contents. Additionally, it makes the set lookup process more
131 efficient as it only requires to check if a file exists.
132
133 I chose the --package-set option over the --set option for explicitly
134 telling portage to emerge a set mostly because --set implies setting
135 an environment variable, or such.
136
137 Allowing sets' USE flags to be manipulated through the ``package.use``
138 file would have done more harm than good, for several reasons:
139
140 - If a USE flag is turned on (i.e. 'foo') for a set and the same USE
141 flag is turned off (i.e. '-foo'), for a package which is part of
142 the set, it is unclear which setting should take precedence.
143
144 - Similarly, if a USE flag is turned on for a set and the same USE flag
145 is turned off for a set that is a subset of the original set, it is
146 unclear which setting should take precedence.
147
148 - If a USE flag is defined (either off or on) for a set and a package
149 that belongs in the set is to be emerged, it is unclear whether the
150 USE flag should be defined when emerging the package in question.
151
152 Therefore, I have decided it would be better to disallow setting USE
153 flags for sets.
154
155 Backwards Compatibility
156 =======================
157
158 Backwards compatibility with the current situation, in which only two
159 system-defined sets exist can be kept in one of two ways:
160
161 1. Leaving the situation as is - the 'world' and 'system' sets are
162 hard-coded in Portage.
163 2. Distributing default 'system' and 'world' files under the
164 ``/etc/portage/sets/`` directory.
165
166 Other than that, there are no other backwards compatibility concerns
167 involved.
168
169 References
170 ==========
171
172 .. [#NAME-RULES] Gentoo Linux Development Policy - Ebuild Policy
173 (http://www.gentoo.org/doc/en/policy.xml#doc_chap3)
174
175 .. [#PORTAGE-MANPAGE]
176 http://www.gentoo.org/cgi-bin/viewcvs.cgi/portage/man/portage.5?root=gentoo-src
177
178 Copyright
179 =========
180
181 This document has been placed in the public domain.

  ViewVC Help
Powered by ViewVC 1.1.20