| 1 |
mgorny |
1.1 |
<?xml version="1.0" encoding="utf-8" ?>
|
| 2 |
|
|
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
| 3 |
|
|
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
|
| 4 |
|
|
|
| 5 |
|
|
<head>
|
| 6 |
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
|
| 7 |
|
|
<meta name="generator" content="Docutils 0.9: http://docutils.sourceforge.net/" />
|
| 8 |
|
|
<title>GLEP 62 -- Optional runtime dependencies via runtime-switchable USE flags</title>
|
| 9 |
|
|
<link rel="stylesheet" href="tools/glep.css" type="text/css" /></head>
|
| 10 |
|
|
<body bgcolor="white">
|
| 11 |
|
|
<table class="navigation" cellpadding="0" cellspacing="0"
|
| 12 |
|
|
width="100%" border="0">
|
| 13 |
|
|
<tr><td class="navicon" width="150" height="35">
|
| 14 |
|
|
<a href="http://www.gentoo.org/" title="Gentoo Linux Home Page">
|
| 15 |
|
|
<img src="http://www.gentoo.org/images/gentoo-new.gif" alt="[Gentoo]"
|
| 16 |
|
|
border="0" width="150" height="35" /></a></td>
|
| 17 |
|
|
<td class="textlinks" align="left">
|
| 18 |
|
|
[<b><a href="http://www.gentoo.org/">Gentoo Linux Home</a></b>]
|
| 19 |
|
|
[<b><a href="http://www.gentoo.org/proj/en/glep">GLEP Index</a></b>]
|
| 20 |
|
|
[<b><a href="http://www.gentoo.org/proj/en/glep/glep-0062.txt">GLEP Source</a></b>]
|
| 21 |
|
|
</td></tr></table>
|
| 22 |
|
|
<table class="rfc2822 docutils field-list" frame="void" rules="none">
|
| 23 |
|
|
<col class="field-name" />
|
| 24 |
|
|
<col class="field-body" />
|
| 25 |
|
|
<tbody valign="top">
|
| 26 |
|
|
<tr class="field"><th class="field-name">GLEP:</th><td class="field-body">62</td>
|
| 27 |
|
|
</tr>
|
| 28 |
|
|
<tr class="field"><th class="field-name">Title:</th><td class="field-body">Optional runtime dependencies via runtime-switchable USE flags</td>
|
| 29 |
|
|
</tr>
|
| 30 |
|
|
<tr class="field"><th class="field-name">Version:</th><td class="field-body">1.2</td>
|
| 31 |
|
|
</tr>
|
| 32 |
|
|
<tr class="field"><th class="field-name">Last-Modified:</th><td class="field-body"><a class="reference external" href="http://www.gentoo.org/cgi-bin/viewcvs.cgi/xml/htdocs/proj/en/glep/glep-0062.txt?cvsroot=gentoo">2012/07/11 20:24:37</a></td>
|
| 33 |
|
|
</tr>
|
| 34 |
|
|
<tr class="field"><th class="field-name">Author:</th><td class="field-body">Michał Górny <mgorny at gentoo.org></td>
|
| 35 |
|
|
</tr>
|
| 36 |
|
|
<tr class="field"><th class="field-name">Status:</th><td class="field-body">Draft</td>
|
| 37 |
|
|
</tr>
|
| 38 |
|
|
<tr class="field"><th class="field-name">Type:</th><td class="field-body">Standards Track</td>
|
| 39 |
|
|
</tr>
|
| 40 |
|
|
<tr class="field"><th class="field-name">Content-Type:</th><td class="field-body"><a class="reference external" href="glep-0002.html">text/x-rst</a></td>
|
| 41 |
|
|
</tr>
|
| 42 |
|
|
<tr class="field"><th class="field-name">Created:</th><td class="field-body">17 Jun 2012</td>
|
| 43 |
|
|
</tr>
|
| 44 |
|
|
<tr class="field"><th class="field-name">Post-History:</th><td class="field-body">11 Jul 2012</td>
|
| 45 |
|
|
</tr>
|
| 46 |
|
|
</tbody>
|
| 47 |
|
|
</table>
|
| 48 |
|
|
<hr />
|
| 49 |
|
|
<div class="contents topic" id="contents">
|
| 50 |
|
|
<p class="topic-title first">Contents</p>
|
| 51 |
|
|
<ul class="simple">
|
| 52 |
|
|
<li><a class="reference internal" href="#abstract" id="id6">Abstract</a></li>
|
| 53 |
|
|
<li><a class="reference internal" href="#motivation" id="id7">Motivation</a></li>
|
| 54 |
|
|
<li><a class="reference internal" href="#specification" id="id8">Specification</a></li>
|
| 55 |
|
|
<li><a class="reference internal" href="#rationale" id="id9">Rationale</a></li>
|
| 56 |
|
|
<li><a class="reference internal" href="#reference-implementation" id="id10">Reference implementation</a></li>
|
| 57 |
|
|
<li><a class="reference internal" href="#backwards-compatibility" id="id11">Backwards compatibility</a></li>
|
| 58 |
|
|
<li><a class="reference internal" href="#copyright" id="id12">Copyright</a></li>
|
| 59 |
|
|
</ul>
|
| 60 |
|
|
</div>
|
| 61 |
|
|
<div class="section" id="abstract">
|
| 62 |
|
|
<h1><a class="toc-backref" href="#id6">Abstract</a></h1>
|
| 63 |
|
|
<p>This GLEP addresses the issue of referencing optional runtime
|
| 64 |
|
|
dependencies in Gentoo packages and ebuilds. It does introduce
|
| 65 |
|
|
a concept of runtime-switchable USE flags to achieve that goal.</p>
|
| 66 |
|
|
</div>
|
| 67 |
|
|
<div class="section" id="motivation">
|
| 68 |
|
|
<h1><a class="toc-backref" href="#id7">Motivation</a></h1>
|
| 69 |
|
|
<p>Optional runtime dependencies are often found in packages installing
|
| 70 |
|
|
various scripts (shell, python, perl). These are not strictly required
|
| 71 |
|
|
for the particular package to work but installing them enables
|
| 72 |
|
|
additional functionality.</p>
|
| 73 |
|
|
<p>Unlike in compiled programs, enabling or disabling those features
|
| 74 |
|
|
(dependencies) does not affect the files installed by the package.
|
| 75 |
|
|
They can be installed and uninstalled independently of the package,
|
| 76 |
|
|
resulting in changes of functionality without a need to rebuild
|
| 77 |
|
|
the package.</p>
|
| 78 |
|
|
<p>Currently such dependencies are usually expressed only through
|
| 79 |
|
|
<tt class="docutils literal">pkg_postinst()</tt> messages. This forces user to manually install
|
| 80 |
|
|
the necessary dependencies, and uninstall them when they are no longer
|
| 81 |
|
|
necessary.</p>
|
| 82 |
|
|
<p>Another solution is to use regular USE flags. Those flags do not strictly
|
| 83 |
|
|
follow the principles of USE flags because they do not affect files
|
| 84 |
|
|
installed by the package and are not entirely effective to the package
|
| 85 |
|
|
(a disabled feature will still be available if necessary dependency is
|
| 86 |
|
|
installed). Additionally, it requires unnecessary rebuilds
|
| 87 |
|
|
of the package in order to change the dependencies.</p>
|
| 88 |
|
|
</div>
|
| 89 |
|
|
<div class="section" id="specification">
|
| 90 |
|
|
<h1><a class="toc-backref" href="#id8">Specification</a></h1>
|
| 91 |
|
|
<p>The ebuilds aiming to provide features enabled through optional runtime
|
| 92 |
|
|
dependencies should:</p>
|
| 93 |
|
|
<ol class="arabic simple">
|
| 94 |
|
|
<li>create regular USE flags for all those features, following
|
| 95 |
|
|
appropriate specifications for Gentoo ebuilds, and including
|
| 96 |
|
|
the flags in the <tt class="docutils literal">IUSE</tt> variable;</li>
|
| 97 |
|
|
<li>introduce additional <tt class="docutils literal">IUSE_RUNTIME</tt> variable listing names of USE
|
| 98 |
|
|
flags related to optional runtime dependencies (without prefixes
|
| 99 |
|
|
related to IUSE defaults).</li>
|
| 100 |
|
|
</ol>
|
| 101 |
|
|
<p>Additionally, the ebuilds must obey the following rules:</p>
|
| 102 |
|
|
<ol class="arabic simple">
|
| 103 |
|
|
<li>all flags listed in <tt class="docutils literal">IUSE_RUNTIME</tt> have to be listed in <tt class="docutils literal">IUSE</tt>
|
| 104 |
|
|
as well,</li>
|
| 105 |
|
|
<li>flags listed in <tt class="docutils literal">IUSE_RUNTIME</tt> can be referenced in <tt class="docutils literal">RDEPEND</tt>,
|
| 106 |
|
|
<tt class="docutils literal">PDEPEND</tt> and <tt class="docutils literal">REQUIRED_USE</tt> variables,</li>
|
| 107 |
|
|
<li>flags listed in <tt class="docutils literal">IUSE_RUNTIME</tt> must not be referenced in phase
|
| 108 |
|
|
functions, <tt class="docutils literal">DEPEND</tt>, <tt class="docutils literal">LICENSE</tt> or <tt class="docutils literal">SRC_URI</tt>,</li>
|
| 109 |
|
|
<li>flags listed in <tt class="docutils literal">IUSE_RUNTIME</tt> can be referenced through USE
|
| 110 |
|
|
dependencies by other packages' <tt class="docutils literal">DEPEND</tt>, <tt class="docutils literal">RDEPEND</tt>
|
| 111 |
|
|
and <tt class="docutils literal">PDEPEND</tt> variables but it is unallowed to request disabling
|
| 112 |
|
|
those flags (only <tt class="docutils literal">[flag]</tt> and <tt class="docutils literal"><span class="pre">[flag?]</span></tt> forms are allowed),</li>
|
| 113 |
|
|
<li>flags listed in <tt class="docutils literal">IUSE_RUNTIME</tt> can be referenced through
|
| 114 |
|
|
<tt class="docutils literal">has_version</tt> and <tt class="docutils literal">best_version</tt> yet the caller must not rely
|
| 115 |
|
|
upon those flags being disabled.</li>
|
| 116 |
|
|
</ol>
|
| 117 |
|
|
<p>The package manager should treat flags listed in <tt class="docutils literal">IUSE_RUNTIME</tt>
|
| 118 |
|
|
as regular USE flags, except for the following:</p>
|
| 119 |
|
|
<ol class="arabic simple">
|
| 120 |
|
|
<li>enabling or disabling any of the flags must not involve rebuilding
|
| 121 |
|
|
the package,</li>
|
| 122 |
|
|
<li>it should be possible for a package manager to change those flags
|
| 123 |
|
|
on a installed package without using the original ebuild <a class="footnote-reference" href="#id3" id="id1">[1]</a>,</li>
|
| 124 |
|
|
<li>when queried on a installed package, the package manager must
|
| 125 |
|
|
consider a particular flag enabled only if its dependencies
|
| 126 |
|
|
are satisfied already <a class="footnote-reference" href="#id4" id="id2">[2]</a>,</li>
|
| 127 |
|
|
<li>the flags may be listed in the visual output in a distinct way
|
| 128 |
|
|
to inform the user that they affect runtime dependencies only.</li>
|
| 129 |
|
|
</ol>
|
| 130 |
|
|
<table class="docutils footnote" frame="void" id="id3" rules="none">
|
| 131 |
|
|
<colgroup><col class="label" /><col /></colgroup>
|
| 132 |
|
|
<tbody valign="top">
|
| 133 |
|
|
<tr><td class="label"><a class="fn-backref" href="#id1">[1]</a></td><td>The package manager has to ensure that all relevant information
|
| 134 |
|
|
is stored in the installed package metadata.</td></tr>
|
| 135 |
|
|
</tbody>
|
| 136 |
|
|
</table>
|
| 137 |
|
|
<table class="docutils footnote" frame="void" id="id4" rules="none">
|
| 138 |
|
|
<colgroup><col class="label" /><col /></colgroup>
|
| 139 |
|
|
<tbody valign="top">
|
| 140 |
|
|
<tr><td class="label"><a class="fn-backref" href="#id2">[2]</a></td><td>The result of this check can be cached when updating the metadata
|
| 141 |
|
|
of installed package, and it is not strictly required that
|
| 142 |
|
|
a package manager must ensure that the dependency graph is still
|
| 143 |
|
|
consistent afterwards.</td></tr>
|
| 144 |
|
|
</tbody>
|
| 145 |
|
|
</table>
|
| 146 |
|
|
</div>
|
| 147 |
|
|
<div class="section" id="rationale">
|
| 148 |
|
|
<h1><a class="toc-backref" href="#id9">Rationale</a></h1>
|
| 149 |
|
|
<p>The proposed solution tries to solve the issue of handling runtime
|
| 150 |
|
|
dependencies while reusing the existing infrastructure. Most
|
| 151 |
|
|
importantly, users will be able to reuse the existing tools
|
| 152 |
|
|
and configuration files to enable and disable optional runtime
|
| 153 |
|
|
and build-time dependencies alike.</p>
|
| 154 |
|
|
<p>The remaining reused features include:</p>
|
| 155 |
|
|
<ul class="simple">
|
| 156 |
|
|
<li>dependency syntax (USE-conditionals),</li>
|
| 157 |
|
|
<li>ability to use <tt class="docutils literal">REQUIRED_USE</tt>, USE dependencies,</li>
|
| 158 |
|
|
<li>ability to describe flags in <cite>metadata.xml</cite>,</li>
|
| 159 |
|
|
<li>global flag names (and descriptions).</li>
|
| 160 |
|
|
</ul>
|
| 161 |
|
|
<p>Alternative proposed solution involved creating additional <tt class="docutils literal">SDEPEND</tt>
|
| 162 |
|
|
variable. That proposition had the following disadvantages:</p>
|
| 163 |
|
|
<ul class="simple">
|
| 164 |
|
|
<li>being package-oriented rather than feature-oriented,</li>
|
| 165 |
|
|
<li>lack of ability to express multiple packages required by a single
|
| 166 |
|
|
feature,</li>
|
| 167 |
|
|
<li>lack of ability to express cross-feature dependencies,</li>
|
| 168 |
|
|
<li>lack of ability to describe features provided by enabled packages,</li>
|
| 169 |
|
|
<li>necessity of implementing a new user interface parts to control
|
| 170 |
|
|
the dependencies,</li>
|
| 171 |
|
|
<li>lack of backwards compatibility.</li>
|
| 172 |
|
|
</ul>
|
| 173 |
|
|
<p>Those disadvantages could be fixed by either extending dependency
|
| 174 |
|
|
syntax alike Exherbo (grouping, annotations) or using USE flags.
|
| 175 |
|
|
The latter is practically equivalent to this solution yet introduces
|
| 176 |
|
|
another variable unnecessarily.</p>
|
| 177 |
|
|
</div>
|
| 178 |
|
|
<div class="section" id="reference-implementation">
|
| 179 |
|
|
<h1><a class="toc-backref" href="#id10">Reference implementation</a></h1>
|
| 180 |
|
|
<p>In order to support runtime-switchable USE flag changes on installed
|
| 181 |
|
|
packages, a package manager should store the following information
|
| 182 |
|
|
in the installed package metadata:</p>
|
| 183 |
|
|
<ol class="arabic simple">
|
| 184 |
|
|
<li>a list of runtime-switchable flags (<tt class="docutils literal">IUSE_RUNTIME</tt>),</li>
|
| 185 |
|
|
<li>a list of runtime dependencies conditional to runtime-switchable
|
| 186 |
|
|
flags, not subjected to USE expansion (relevant part of <tt class="docutils literal">RDEPEND</tt>),</li>
|
| 187 |
|
|
<li>a list of <tt class="docutils literal">REQUIRED_USE</tt> constraints relevant to runtime-switchable
|
| 188 |
|
|
USE flags.</li>
|
| 189 |
|
|
</ol>
|
| 190 |
|
|
<p>The package manager should be also able to update the list of effective
|
| 191 |
|
|
USE flags in installed package metadata (<tt class="docutils literal">USE</tt>) without rebuilding
|
| 192 |
|
|
the package.</p>
|
| 193 |
|
|
<p>The following procedure should apply when a dependency atom is
|
| 194 |
|
|
considered (either as a package dependency or user-requested atom):</p>
|
| 195 |
|
|
<ol class="arabic simple">
|
| 196 |
|
|
<li>if the dependency is not satisfied with an installed package,
|
| 197 |
|
|
perform the dependency resolution on ebuilds as usual (in order to
|
| 198 |
|
|
install a new package);</li>
|
| 199 |
|
|
<li>if runtime-switchable USE updates are disabled, continue to
|
| 200 |
|
|
the next dependency (with this one satisfied);</li>
|
| 201 |
|
|
<li><tt class="docutils literal">current_use</tt> = installed package metadata . <tt class="docutils literal">USE</tt>;</li>
|
| 202 |
|
|
<li><tt class="docutils literal">effective_use</tt> = requested <tt class="docutils literal">USE</tt> for the package;</li>
|
| 203 |
|
|
<li><tt class="docutils literal">use_changes</tt> = <tt class="docutils literal">current_use</tt> xor <tt class="docutils literal">effective_use</tt>;</li>
|
| 204 |
|
|
<li>if <tt class="docutils literal">use_changes</tt> is empty, continue to the next dependency;</li>
|
| 205 |
|
|
<li><tt class="docutils literal">iuse_runtime</tt> = installed package metadata . <tt class="docutils literal">IUSE_RUNTIME</tt>;</li>
|
| 206 |
|
|
<li><tt class="docutils literal">reg_use_changes</tt> = <tt class="docutils literal">use_changes</tt> and not <tt class="docutils literal">iuse_runtime</tt>;</li>
|
| 207 |
|
|
<li>if <tt class="docutils literal">reg_use_changes</tt> is not empty and regular USE updates
|
| 208 |
|
|
are enabled, perform the dependency resolution on ebuilds (in order
|
| 209 |
|
|
to rebuild the package);</li>
|
| 210 |
|
|
<li><tt class="docutils literal">run_use_changes</tt> = <tt class="docutils literal">use_changes</tt> and <tt class="docutils literal">iuse_runtime</tt>;</li>
|
| 211 |
|
|
<li>if <tt class="docutils literal">run_use_changes</tt> is empty, continue to the next dependency;</li>
|
| 212 |
|
|
<li><tt class="docutils literal">required_use</tt> = installed package metadata . <tt class="docutils literal">REQUIRED_USE</tt>;</li>
|
| 213 |
|
|
<li>perform a check for <tt class="docutils literal">required_use</tt> constraints being satisfied
|
| 214 |
|
|
by <tt class="docutils literal">effective_use</tt>;</li>
|
| 215 |
|
|
<li><tt class="docutils literal">run_rdepend</tt> = installed package metadata . <tt class="docutils literal">RDEPEND</tt> (with
|
| 216 |
|
|
unexpanded <tt class="docutils literal">IUSE_RUNTIME</tt> conditionals);</li>
|
| 217 |
|
|
<li>perform the dependency resolution for <tt class="docutils literal">run_rdepend</tt> with
|
| 218 |
|
|
<tt class="docutils literal">effective_use</tt>,</li>
|
| 219 |
|
|
<li>queue the package for runtime-switchable USE update.</li>
|
| 220 |
|
|
</ol>
|
| 221 |
|
|
<p>Furthermore, after installing all dependencies introduced by the above
|
| 222 |
|
|
procedure (<tt class="docutils literal">run_rdepend</tt> resolution), if a package was queued for
|
| 223 |
|
|
runtime-switchable USE update, the package manager should write a new
|
| 224 |
|
|
value for <tt class="docutils literal">USE</tt> key in installed package metadata.</p>
|
| 225 |
|
|
</div>
|
| 226 |
|
|
<div class="section" id="backwards-compatibility">
|
| 227 |
|
|
<h1><a class="toc-backref" href="#id11">Backwards compatibility</a></h1>
|
| 228 |
|
|
<p>Package managers not implementing this GLEP will consider
|
| 229 |
|
|
the <tt class="docutils literal">IUSE_RUNTIME</tt> variable as an irrelevant bash variable and treat
|
| 230 |
|
|
runtime-switchable USE flags as regular USE flags. The dependency tree
|
| 231 |
|
|
will still be consistent yet packages may be rebuilt unnecessarily.</p>
|
| 232 |
|
|
</div>
|
| 233 |
|
|
<div class="section" id="copyright">
|
| 234 |
|
|
<h1><a class="toc-backref" href="#id12">Copyright</a></h1>
|
| 235 |
|
|
<p>This document has been placed in the public domain.</p>
|
| 236 |
|
|
</div>
|
| 237 |
|
|
|
| 238 |
|
|
</div>
|
| 239 |
|
|
<div class="footer">
|
| 240 |
|
|
<hr class="footer" />
|
| 241 |
|
|
<a class="reference external" href="glep-0062.txt">View document source</a>.
|
| 242 |
|
|
Generated on: 2012-07-11 20:57 UTC.
|
| 243 |
|
|
Generated by <a class="reference external" href="http://docutils.sourceforge.net/">Docutils</a> from <a class="reference external" href="http://docutils.sourceforge.net/rst.html">reStructuredText</a> source.
|
| 244 |
|
|
|
| 245 |
|
|
</div>
|
| 246 |
|
|
</body>
|
| 247 |
|
|
</html>
|
Parent Directory
| 
Revision Log
