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<tr class="field"><th class="field-name">GLEP:</th><td class="field-body">56</td> |
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</tr> |
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<tr class="field"><th class="field-name">Title:</th><td class="field-body">USE flag descriptions in metadata</td> |
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</tr> |
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<tr class="field"><th class="field-name">Version:</th><td class="field-body">1.4</td> |
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</tr> |
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<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-0056.txt?cvsroot=gentoo">2008/09/02 20:37:40</a></td> |
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</tr> |
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<tr class="field"><th class="field-name">Author:</th><td class="field-body">Doug Goldstein <cardoe at gentoo.org></td> |
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</tr> |
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<tr class="field"><th class="field-name">Status:</th><td class="field-body">Final</td> |
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</tr> |
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<tr class="field"><th class="field-name">Type:</th><td class="field-body">Standards Track</td> |
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</tr> |
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<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> |
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</tr> |
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<tr class="field"><th class="field-name">Created:</th><td class="field-body">03-Jun-2008</td> |
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</tr> |
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<tr class="field"><th class="field-name">Post-History:</th><td class="field-body">05-June-2008, 13-Jun-2008</td> |
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</tr> |
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</tbody> |
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</table> |
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<hr /> |
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<div class="contents topic" id="contents"> |
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<p class="topic-title first">Contents</p> |
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<ul class="simple"> |
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<li><a class="reference internal" href="#abstract" id="id12">Abstract</a></li> |
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<li><a class="reference internal" href="#motivation" id="id13">Motivation</a></li> |
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<li><a class="reference internal" href="#specification" id="id14">Specification</a></li> |
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<li><a class="reference internal" href="#credits" id="id15">Credits</a></li> |
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<li><a class="reference internal" href="#references" id="id16">References</a></li> |
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<li><a class="reference internal" href="#backwards-compatibility" id="id17">Backwards Compatibility</a></li> |
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<li><a class="reference internal" href="#copyright" id="id18">Copyright</a></li> |
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</ul> |
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</div> |
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<div class="section" id="abstract"> |
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<h1><a class="toc-backref" href="#id12">Abstract</a></h1> |
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<p>This GLEP proposes to add per-package USE flag descriptions to each package's |
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metadata.</p> |
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</div> |
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<div class="section" id="motivation"> |
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<h1><a class="toc-backref" href="#id13">Motivation</a></h1> |
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<p>Gives Gentoo users the ability to better identify how USE flags affect their |
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installations of a given package. For example, many global USE flags have very |
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generic descriptions but no specifics on how it affects a certain package. |
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Specifically speaking, an example would be net-print/cups and the 'jpeg' USE |
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flag. Does this flag mean you won't be able to print jpeg files? You can print |
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them directly? It's interface won't use jpeg files.</p> |
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<blockquote> |
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<ul class="simple"> |
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<li>Motivator References: <a class="footnote-reference" href="#motivators1" id="id1">[6]</a>, <a class="footnote-reference" href="#motivators2" id="id2">[7]</a>, <a class="footnote-reference" href="#motivators3" id="id3">[8]</a>, |
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and <a class="footnote-reference" href="#motivators4" id="id4">[9]</a></li> |
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</ul> |
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</blockquote> |
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</div> |
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<div class="section" id="specification"> |
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<h1><a class="toc-backref" href="#id14">Specification</a></h1> |
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<p>This GLEP proposes the addition of <tt class="docutils literal"><use></tt> XML tag that is only allowed to |
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appear inside of a <tt class="docutils literal"><pkgmetadata></tt> XML tag.</p> |
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<blockquote> |
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<ul> |
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<li><p class="first">Inside the <tt class="docutils literal"><use></tt> XML tag, the <tt class="docutils literal"><flag></tt> XML tag is allowed to appear |
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once per USE flag as specified by the <tt class="docutils literal">'name'</tt> attribute with the |
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following exception:</p> |
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<ul class="simple"> |
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<li>The <tt class="docutils literal">'restrict'</tt> atttribute can limit to specific versions of the |
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package, where the attribute value must be a valid CPV as defined by the |
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<cite>Gentoo Developer Handbook</cite> <a class="footnote-reference" href="#devhandbook" id="id5">[4]</a>. This follows the current |
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behavior of the <tt class="docutils literal">'restrict'</tt> attribute in metadata.xml.<ul> |
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<li>e.g. A USE flag may have one behavior for version 0.1 of a package, |
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while version 0.2, the USE flag may differ slightly.</li> |
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</ul> |
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</li> |
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</ul> |
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</li> |
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<li><p class="first">Each <tt class="docutils literal"><flag></tt> XML tag requires a 'name' attribute which is the full USE |
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flag name as it would appear in the IUSE section of the ebuild.</p> |
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<blockquote> |
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<ul class="simple"> |
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<li>e.g. "video_cards_i810" or "alsa"</li> |
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</ul> |
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</blockquote> |
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</li> |
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<li><p class="first">Each <tt class="docutils literal"><flag></tt> XML tag allows 0 or more nested <tt class="docutils literal"><pkg></tt> XML tags whose |
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character data is a valid CP or CPV as defined by the |
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<cite>Gentoo Development Manual - Ebuild File Format</cite> <a class="footnote-reference" href="#devmanual" id="id6">[5]</a>.</p> |
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</li> |
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<li><p class="first">Each <tt class="docutils literal"><flag></tt> XML tag allows 0 or more nested <tt class="docutils literal"><cat></tt> XML tags whose |
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character data is a valid category.</p> |
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</li> |
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<li><p class="first">The <tt class="docutils literal"><use></tt> XML tag may appear multiple times inside of the |
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<tt class="docutils literal"><pkgmetadata></tt> XML tag if and only if it contains a different <tt class="docutils literal">'lang'</tt> |
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attribute value.</p> |
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<ul class="simple"> |
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<li>The <tt class="docutils literal">lang</tt> attribute follows the documented <tt class="docutils literal">lang</tt> attribute in the |
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<cite>Gentoo Developer Handbook</cite> <a class="footnote-reference" href="#devhandbook" id="id7">[4]</a>.</li> |
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</ul> |
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</li> |
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</ul> |
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</blockquote> |
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<p>Documentation for the <cite>Gentoo Developer Handbook</cite> <a class="footnote-reference" href="#devhandbook" id="id8">[4]</a> and the |
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metadata.dtd can be found in Gentoo's Bugzilla <a class="footnote-reference" href="#use-flag-metadata-bug" id="id9">[1]</a> |
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bug #199788.</p> |
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<p>The following are two concrete examples in tree, <a class="footnote-reference" href="#use-flag-metadata-example1" id="id10">[2]</a> |
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and <a class="footnote-reference" href="#use-flag-metadata-example2" id="id11">[3]</a>.</p> |
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<p>And the following is an embedded example and not from a real package:</p> |
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<pre class="literal-block"> |
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<use> |
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<flag name='acpi'>Enables HAL to attempt to read from |
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/proc/acpi/event, if unavailable, HAL will read events from |
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<pkg>sys-power/acpid</pkg>. If you need multiple acpi readers, |
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ensure acpid is in your default runlevel |
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(rc-update add acpid default) along with HAL. This will also |
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enable HAL to read Toshiba and IBM acpi events which do not |
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get sent via /proc/acpi/event</flag> |
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<flag name='spell'>Enables spell checking capability using |
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dictionaries found in <cat>app-dict</cat></flag> |
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</use> |
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</pre> |
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</div> |
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<div class="section" id="credits"> |
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<h1><a class="toc-backref" href="#id15">Credits</a></h1> |
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<p>Thanks to the following persons for their input on or related to this GLEP |
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(even though they might not have known it): |
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Diego Pettenò (flameeyes), Alec Warner (antarus), Joshua Nichols (nichoj), |
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Steve Dibb (beandog), and Tiziano Müller (dev-zero)</p> |
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</div> |
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<div class="section" id="references"> |
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<h1><a class="toc-backref" href="#id16">References</a></h1> |
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<table class="docutils footnote" frame="void" id="use-flag-metadata-bug" rules="none"> |
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<colgroup><col class="label" /><col /></colgroup> |
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<tbody valign="top"> |
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<tr><td class="label"><a class="fn-backref" href="#id9">[1]</a></td><td><a class="reference external" href="http://bugs.gentoo.org/show_bug.cgi?id=199788">http://bugs.gentoo.org/show_bug.cgi?id=199788</a></td></tr> |
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</tbody> |
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</table> |
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<table class="docutils footnote" frame="void" id="use-flag-metadata-example1" rules="none"> |
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<colgroup><col class="label" /><col /></colgroup> |
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<tbody valign="top"> |
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<tr><td class="label"><a class="fn-backref" href="#id10">[2]</a></td><td><a class="reference external" href="http://sources.gentoo.org/viewcvs.py/gentoo-x86/sys-apps/hal/metadata.xml?view=markup">http://sources.gentoo.org/viewcvs.py/gentoo-x86/sys-apps/hal/metadata.xml?view=markup</a></td></tr> |
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</tbody> |
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</table> |
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<table class="docutils footnote" frame="void" id="use-flag-metadata-example2" rules="none"> |
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<colgroup><col class="label" /><col /></colgroup> |
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<tbody valign="top"> |
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<tr><td class="label"><a class="fn-backref" href="#id11">[3]</a></td><td><a class="reference external" href="http://sources.gentoo.org/viewcvs.py/gentoo-x86/media-tv/mythtv/metadata.xml?view=markup">http://sources.gentoo.org/viewcvs.py/gentoo-x86/media-tv/mythtv/metadata.xml?view=markup</a></td></tr> |
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</tbody> |
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</table> |
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<table class="docutils footnote" frame="void" id="devhandbook" rules="none"> |
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<colgroup><col class="label" /><col /></colgroup> |
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<tbody valign="top"> |
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<tr><td class="label">[4]</td><td><em>(<a class="fn-backref" href="#id5">1</a>, <a class="fn-backref" href="#id7">2</a>, <a class="fn-backref" href="#id8">3</a>)</em> <a class="reference external" href="http://www.gentoo.org/proj/en/devrel/handbook/handbook.xml?part=2&chap=4">http://www.gentoo.org/proj/en/devrel/handbook/handbook.xml?part=2&chap=4</a></td></tr> |
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</tbody> |
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</table> |
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<table class="docutils footnote" frame="void" id="devmanual" rules="none"> |
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<colgroup><col class="label" /><col /></colgroup> |
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<tbody valign="top"> |
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<tr><td class="label"><a class="fn-backref" href="#id6">[5]</a></td><td><a class="reference external" href="http://devmanual.gentoo.org/ebuild-writing/file-format/index.html">http://devmanual.gentoo.org/ebuild-writing/file-format/index.html</a></td></tr> |
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</tbody> |
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</table> |
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<table class="docutils footnote" frame="void" id="motivators1" rules="none"> |
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<colgroup><col class="label" /><col /></colgroup> |
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<tbody valign="top"> |
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<tr><td class="label"><a class="fn-backref" href="#id1">[6]</a></td><td><a class="reference external" href="http://blog.flameeyes.eu/articles/2007/11/19/lets-actually-get-some-metadata">http://blog.flameeyes.eu/articles/2007/11/19/lets-actually-get-some-metadata</a></td></tr> |
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</tbody> |
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</table> |
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<table class="docutils footnote" frame="void" id="motivators2" rules="none"> |
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<colgroup><col class="label" /><col /></colgroup> |
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<tbody valign="top"> |
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<tr><td class="label"><a class="fn-backref" href="#id2">[7]</a></td><td><a class="reference external" href="http://blog.cardoe.com/archives/2007/11/19/use-flag-metadata/">http://blog.cardoe.com/archives/2007/11/19/use-flag-metadata/</a></td></tr> |
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</tbody> |
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</table> |
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<table class="docutils footnote" frame="void" id="motivators3" rules="none"> |
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<colgroup><col class="label" /><col /></colgroup> |
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<tbody valign="top"> |
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<tr><td class="label"><a class="fn-backref" href="#id3">[8]</a></td><td><a class="reference external" href="http://blog.cardoe.com/archives/2007/11/23/metadataxml-updates-examples/">http://blog.cardoe.com/archives/2007/11/23/metadataxml-updates-examples/</a></td></tr> |
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</tbody> |
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</table> |
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<table class="docutils footnote" frame="void" id="motivators4" rules="none"> |
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<colgroup><col class="label" /><col /></colgroup> |
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<tbody valign="top"> |
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<tr><td class="label"><a class="fn-backref" href="#id4">[9]</a></td><td><a class="reference external" href="http://technicalpickles.com/posts/pidgin-idle-time">http://technicalpickles.com/posts/pidgin-idle-time</a></td></tr> |
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</tbody> |
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</table> |
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</div> |
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<div class="section" id="backwards-compatibility"> |
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<h1><a class="toc-backref" href="#id17">Backwards Compatibility</a></h1> |
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<p>No changes are necessary to existing <tt class="docutils literal">metadata.xml</tt> files. Information in |
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the new tags is not mandatory. Tools that currently read <tt class="docutils literal">metadata.xml</tt> |
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files may break if written poorly, while well written tools should just ignore |
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the additional elements. Tools which are capable of handling the new tags |
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should prefer their data over <tt class="docutils literal">use.desc</tt> and <tt class="docutils literal">use.local.desc</tt>.</p> |
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<p>USE flags still must be defined in <tt class="docutils literal">use.desc</tt> or <tt class="docutils literal">use.local.desc</tt>. If the |
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USE flag is not found in either <tt class="docutils literal">use.desc</tt> or <tt class="docutils literal">use.local.desc</tt>, the |
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information contained within the new tags in <tt class="docutils literal">metadata.xml</tt> must be ignored |
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and QA tools should warn as they currently do.</p> |
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<p>Once this GLEP is approved, the Gentoo Infrastructure Team will work to remove |
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the <tt class="docutils literal">use.local.desc</tt> file from CVS and it will be auto-generated for rsync. |
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This will ensure that backwards compatibility is not broken for users of |
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non-CVS trees. At this time, QA tools will need to be updated to verify the |
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contents of <tt class="docutils literal">metadata.xml</tt> containing the necessary tags which would appear |
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in <tt class="docutils literal">use.local.desc</tt>.</p> |
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</div> |
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<div class="section" id="copyright"> |
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<h1><a class="toc-backref" href="#id18">Copyright</a></h1> |
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<p>This document is placed into the public domain.</p> |
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<!-- vim: set ft=glep tw=72 : --> |
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</div> |
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<a class="reference external" href="glep-0056.txt">View document source</a>. |
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