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12 <title>GLEP 21 -- User-defined Package Sets</title>
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28 <table class="rfc2822 field-list" frame="void" rules="none">
29 <col class="field-name" />
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32 <tr class="field"><th class="field-name">GLEP:</th><td class="field-body">21</td>
33 </tr>
34 <tr class="field"><th class="field-name">Title:</th><td class="field-body">User-defined Package Sets</td>
35 </tr>
36 <tr class="field"><th class="field-name">Version:</th><td class="field-body">1.2</td>
37 </tr>
38 <tr class="field"><th class="field-name">Last-Modified:</th><td class="field-body"><a class="reference" href="http://www.gentoo.org/cgi-bin/viewcvs.cgi/xml/htdocs/proj/en/glep/glep-0021.txt?cvsroot=gentoo">2004/03/07 23:20:54</a></td>
39 </tr>
40 <tr class="field"><th class="field-name">Author:</th><td class="field-body">Tal Peer &lt;coredumb&#32;&#97;t&#32;gentoo.org&gt;</td>
41 </tr>
42 <tr class="field"><th class="field-name">Status:</th><td class="field-body">Draft</td>
43 </tr>
44 <tr class="field"><th class="field-name">Type:</th><td class="field-body">Standards Track</td>
45 </tr>
46 <tr class="field"><th class="field-name">Discussed-To:</th><td class="field-body"><a class="reference" href="mailto:gentoo-portage-dev&#64;lists.gentoo.org">gentoo-portage-dev&#64;lists.gentoo.org</a></td>
47 </tr>
48 <tr class="field"><th class="field-name">Content-Type:</th><td class="field-body"><a class="reference" href="glep-0002.html">text/x-rst</a></td>
49 </tr>
50 <tr class="field"><th class="field-name">Created:</th><td class="field-body">22-Feb-2004</td>
51 </tr>
52 <tr class="field"><th class="field-name">Post-History:</th><td class="field-body">6-Mar-2004</td>
53 </tr>
54 </tbody>
55 </table>
56 <hr />
57 <div class="contents topic" id="contents">
58 <p class="topic-title"><a name="contents">Contents</a></p>
59 <ul class="simple">
60 <li><a class="reference" href="#abstract" id="id3" name="id3">Abstract</a></li>
61 <li><a class="reference" href="#motivation" id="id4" name="id4">Motivation</a></li>
62 <li><a class="reference" href="#specification" id="id5" name="id5">Specification</a><ul>
63 <li><a class="reference" href="#using-user-defined-sets-with-emerge" id="id6" name="id6">Using User-defined Sets With Emerge</a></li>
64 <li><a class="reference" href="#compatibility-with-other-portage-features" id="id7" name="id7">Compatibility With Other Portage Features</a></li>
65 </ul>
66 </li>
67 <li><a class="reference" href="#implementation" id="id8" name="id8">Implementation</a></li>
68 <li><a class="reference" href="#rationale" id="id9" name="id9">Rationale</a></li>
69 <li><a class="reference" href="#backwards-compatibility" id="id10" name="id10">Backwards Compatibility</a></li>
70 <li><a class="reference" href="#references" id="id11" name="id11">References</a></li>
71 <li><a class="reference" href="#copyright" id="id12" name="id12">Copyright</a></li>
72 </ul>
73 </div>
74 <div class="section" id="abstract">
75 <h1><a class="toc-backref" href="#id3" name="abstract">Abstract</a></h1>
76 <p>In Portage, package sets (formerly known as 'classes' or 'targets')
77 are mere groups of packages, grouped together to allow easier updating
78 and handling of them. Currently it is impossible to define sets further
79 than the two default ones: &quot;system&quot; and &quot;world&quot;.</p>
80 </div>
81 <div class="section" id="motivation">
82 <h1><a class="toc-backref" href="#id4" name="motivation">Motivation</a></h1>
83 <p>Over the months, quite a few requests for user-defined sets were
84 made by users and developers, either by posting bugs, messages to
85 mailing lists or on IRC. Usually the response is that this is an
86 awesome idea, but no one ever took the time to actually define it
87 properly and implement it.</p>
88 <p>This document offers a specification for the implementation of
89 user-defined sets using configuration files similar to the current
90 world/system sets use.</p>
91 </div>
92 <div class="section" id="specification">
93 <h1><a class="toc-backref" href="#id5" name="specification">Specification</a></h1>
94 <p>The proposed implementation uses a one file per set approach, meaning
95 each package set is defined in a single file. All set definition files
96 will reside in a directory <tt class="literal"><span class="pre">/etc/portage/sets/</span></tt> and each set's name
97 will be its file name. Therefore, if one defines a set in
98 /etc/portage/sets/foo-set, the set name will be 'foo-set'. Usual
99 package naming rules <a class="footnote-reference" href="#name-rules" id="id1" name="id1">[1]</a> also apply to sets.</p>
100 <p>As it is impossible to create two or more files with identical names
101 in the same directory, a theoretic conflict between two different sets
102 sharing the same name is impossible. However, users may define a
103 package set whose name conflicts with one more or packages (for ambiguity
104 resolution, see below).</p>
105 <p>Syntax for the package list file is the same as the world file syntax,
106 as described in the Portage manpage <a class="footnote-reference" href="#portage-manpage" id="id2" name="id2">[2]</a>, with one
107 addition: sets may not be 'inherited' by other sets, only packages may
108 be listed. There is no limitation to the number of packages in a set
109 or to the number of sets a package may belong to.</p>
110 <div class="section" id="using-user-defined-sets-with-emerge">
111 <h2><a class="toc-backref" href="#id6" name="using-user-defined-sets-with-emerge">Using User-defined Sets With Emerge</a></h2>
112 <p>The user-defined sets will be available either directly or using
113 the --package-set option, As in:</p>
114 <pre class="literal-block">
115 # Basically the same:
116 emerge foo-set
117 emerge --package-set foo-set
118 </pre>
119 <p>The --package-set option is introduced to bypass ambiguities, as
120 illustrated in the next example:</p>
121 <pre class="literal-block">
122 emerge foo # Where foo is both a set and a one or more
123 # existing packages. This will cause emerge to show
124 # the ambiguity, ask us to be more
125 # specific, and stop.
126
127 emerge --package-set foo # So we specify that what we actually
128 # meant was the package set.
129
130 emerge cat-bar/foo # Or we specify the exact package name.
131 </pre>
132 <p>When running emerge with the --pretend option, sets will be
133 expanded to the packages they are comprised off in the output, as with
134 the current system-defined sets.</p>
135 <p>Only one set may be passed to portage at time, and sets can not
136 be mixed with ordinary packages. Thus, the following snippets are
137 all invalid and will result in an error (assuming <tt class="literal"><span class="pre">foo-set</span></tt> and
138 <tt class="literal"><span class="pre">bar-set</span></tt> are defined as sets):</p>
139 <pre class="literal-block">
140 emerge foo-set glibc
141 emerge bar-set system
142 emerge world foo-set gcc
143 </pre>
144 </div>
145 <div class="section" id="compatibility-with-other-portage-features">
146 <h2><a class="toc-backref" href="#id7" name="compatibility-with-other-portage-features">Compatibility With Other Portage Features</a></h2>
147 <ul class="simple">
148 <li>Dependencies:
149 Package sets (both system-defined and user-defined) may not be
150 depended on by ordinary packages and eclasses.</li>
151 <li>package.mask:
152 Masking a package set through the <tt class="literal"><span class="pre">package.mask</span></tt> file is forbidden.
153 In order to 'mask' a package set, one should move it away from the
154 sets directory.</li>
155 <li>package.use:
156 USE flags may not be defined for sets in the <tt class="literal"><span class="pre">package.use</span></tt> file.</li>
157 </ul>
158 </div>
159 </div>
160 <div class="section" id="implementation">
161 <h1><a class="toc-backref" href="#id8" name="implementation">Implementation</a></h1>
162 <p>The implementation of the package sets concept in Portage should be
163 mostly done in portage.py, and only the interface parts should be
164 added to emerge itself, to keep the separation between interface and
165 logic.</p>
166 <p>The amount of work needed for implementation is not trivial, but not
167 huge either.</p>
168 </div>
169 <div class="section" id="rationale">
170 <h1><a class="toc-backref" href="#id9" name="rationale">Rationale</a></h1>
171 <p>The one file per set approach makes it easy to list the sets which are
172 defined on a system by just listing the <tt class="literal"><span class="pre">/etc/portage/sets</span></tt>
173 directory contents. Additionally, it makes the set lookup process more
174 efficient as it only requires to check if a file exists.</p>
175 <p>I chose the --package-set option over the --set option for explicitly
176 telling portage to emerge a set mostly because --set implies setting
177 an environment variable, or such.</p>
178 <p>Allowing sets' USE flags to be manipulated through the <tt class="literal"><span class="pre">package.use</span></tt>
179 file would have done more harm than good, for several reasons:</p>
180 <ul class="simple">
181 <li>If a USE flag is turned on (i.e. 'foo') for a set and the same USE
182 flag is turned off (i.e. '-foo'), for a package which is part of
183 the set, it is unclear which setting should take precedence.</li>
184 <li>Similarly, if a USE flag is turned on for a set and the same USE flag
185 is turned off for a set that is a subset of the original set, it is
186 unclear which setting should take precedence.</li>
187 <li>If a USE flag is defined (either off or on) for a set and a package
188 that belongs in the set is to be emerged, it is unclear whether the
189 USE flag should be defined when emerging the package in question.</li>
190 </ul>
191 <p>Therefore, I have decided it would be better to disallow setting USE
192 flags for sets.</p>
193 </div>
194 <div class="section" id="backwards-compatibility">
195 <h1><a class="toc-backref" href="#id10" name="backwards-compatibility">Backwards Compatibility</a></h1>
196 <p>Backwards compatibility with the current situation, in which only two
197 system-defined sets exist can be kept in one of two ways:</p>
198 <ol class="arabic simple">
199 <li>Leaving the situation as is - the 'world' and 'system' sets are
200 hard-coded in Portage.</li>
201 <li>Distributing default 'system' and 'world' files under the
202 <tt class="literal"><span class="pre">/etc/portage/sets/</span></tt> directory.</li>
203 </ol>
204 <p>Other than that, there are no other backwards compatibility concerns
205 involved.</p>
206 </div>
207 <div class="section" id="references">
208 <h1><a class="toc-backref" href="#id11" name="references">References</a></h1>
209 <table class="footnote" frame="void" id="name-rules" rules="none">
210 <colgroup><col class="label" /><col /></colgroup>
211 <tbody valign="top">
212 <tr><td class="label"><a class="fn-backref" href="#id1" name="name-rules">[1]</a></td><td>Gentoo Linux Development Policy - Ebuild Policy
213 (<a class="reference" href="http://www.gentoo.org/doc/en/policy.xml#doc_chap3">http://www.gentoo.org/doc/en/policy.xml#doc_chap3</a>)</td></tr>
214 </tbody>
215 </table>
216 <table class="footnote" frame="void" id="portage-manpage" rules="none">
217 <colgroup><col class="label" /><col /></colgroup>
218 <tbody valign="top">
219 <tr><td class="label"><a class="fn-backref" href="#id2" name="portage-manpage">[2]</a></td><td><a class="reference" href="http://www.gentoo.org/cgi-bin/viewcvs.cgi/portage/man/portage.5?root=gentoo-src">http://www.gentoo.org/cgi-bin/viewcvs.cgi/portage/man/portage.5?root=gentoo-src</a></td></tr>
220 </tbody>
221 </table>
222 </div>
223 <div class="section" id="copyright">
224 <h1><a class="toc-backref" href="#id12" name="copyright">Copyright</a></h1>
225 <p>This document has been placed in the public domain.</p>
226 </div>
227 </div>
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