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+<?xml version="1.0"?>
+<guide self="ebuild-writing/using-eclasses/">
+<chapter>
+<title>Using Eclasses</title>
+
+<body>
+<p>
+An eclass is a collection (library) of functions or functionality that is shared
+between packages. See `Eclass Writing Guide`_ for the full story on what
+eclasses can do, how they work and how to write them, and `Eclass Reference`_
+for documentation on various commonly used eclasses. This section only explains
+how to use an eclass which has already been written.
+</p>
+</body>
+
+<section>
+<title>The <c>inherit</c> Function</title>
+<body>
+
+<p>
+To use an eclass, it must be 'inherited'. This is done via the <c>inherit</c>
+function, which is provided by <c>ebuild.sh</c>. The <c>inherit</c> statement must
+come at the top of the ebuild, *before* any functions. Conditional inherits are
+illegal (except where the inheritance criteria are cache-constant -- see `The
+Portage Cache`_).
+</p>
+
+<p>
+After inheriting an eclass, its provided functions can be used as normal. Here's
+<c>devtodo-0.1.18-r2.ebuild</c>, which uses three eclasses:
+</p>
+
+<codesample lang="ebuild">
+# Copyright 1999-2005 Gentoo Foundation
+# Distributed under the terms of the GNU General Public License v2
+# $Header: $
+
+inherit eutils bash-completion flag-o-matic
+
+DESCRIPTION="A nice command line todo list for developers"
+HOMEPAGE="http://swapoff.org/DevTodo"
+SRC_URI="http://swapoff.org/files/${PN}/${P}.tar.gz"
+
+LICENSE="GPL-2"
+SLOT="0"
+KEYWORDS="alpha amd64 arm hppa ia64 mips ppc s390 sparc x86 ppc64"
+IUSE=""
+
+RDEPEND=">=sys-libs/ncurses-5.2
+    >=sys-libs/readline-4.1"
+DEPEND="${RDEPEND}"
+
+src_unpack() {
+    unpack ${A}
+    cd ${S}
+    epatch ${FILESDIR}/${P}-gentoo.diff
+}
+
+src_compile() {
+    einfo "Running autoreconf"
+    autoreconf -f -i || die "autoreconf failed"
+    replace-flags -O? -O1
+    econf --sysconfdir=/etc/devtodo || die "econf failed"
+    emake || die "emake failed"
+}
+
+src_install() {
+    make DESTDIR=${D} install || die "make install failed"
+    dodoc AUTHORS ChangeLog QuickStart README TODO doc/scripts.sh \
+    doc/scripts.tcsh doc/todorc.example contrib/tdrec || die "dodoc failed"
+    dobashcompletion ${FILESDIR}/${PN}.bash-completion ${PN}
+}
+
+pkg_postinst() {
+    echo
+    einfo "Because of a conflict with app-misc/tdl, the tdl symbolic link"
+    einfo "and manual page have been removed."
+    bash-completion_pkg_postinst
+}
+</codesample>
+
+<p>
+Note the <c>inherit</c> immediately after the header.
+</p>
+
+<p>
+The <c>eutils</c> eclass (see `eutils.eclass Reference`_) is needed to get the
+<c>epatch</c> function.  The <c>flag-o-matic</c> eclass (see `flag-o-matic.eclass
+Reference`_) is needed for <c>replace-flags</c>, and the <c>bash-completion</c> eclass
+(`bash-completion.eclass Reference`_) is used to handle the bash completion file
+via <c>dobashcompletion</c> and <c>bash-completion_pkg_postinst</c>.
+</p>
+
+</body>
+</section>
+
+</chapter>
+</guide>