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<title>AntLib</title>
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<body>
<h2><a name="antlib">Antlib</a></h2>
<h3>Description</h3>
<p>
An antlib file is an xml file with a root element of "antlib".
Antlib's elements are ant definition tasks - like
and <a href="../CoreTasks/taskdef.html">Taskdef</a>,
or any ant task that extends
<code>org.apache.tools.ant.taskdefs.AntlibDefinition</code>.
</p>
<p>
The current set of declarations bundled with Ant that do this are:
</p>
<ol>
<li><a href="../CoreTasks/typedef.html">Typedef</a>
</li>
<li><a href="../CoreTasks/taskdef.html">Taskdef</a>
</li>
<li><a href="../CoreTasks/macrodef.html">Macrodef</a>
</li>
<li><a href="../CoreTasks/presetdef.html">Presetdef</a>
</li>
<li><a href="../OptionalTasks/scriptdef.html">Scriptdef</a>
</li>
</ol>
<p>
A group of tasks and types may be defined together in an antlib
file. For example the file <i>sample.xml</i> contains the following:
</p>
<blockquote>
<pre>
<?xml version="1.0"?>
<antlib>
<typedef name="if" classname="org.acme.ant.If"/>
<typedef name="scriptpathmapper"
classname="org.acme.ant.ScriptPathMapper"
onerror="ignore"/>
<macrodef name="print">
<attribute name="file"/>
<sequential>
<concat taskname="print">
<fileset dir="." includes="@{file}"/>
</concat>
</sequential>
</macrodef>
</antlib>
</pre>
</blockquote>
<p>
It defines two types or tasks, <i>if</i> and <i>scriptpathmapper</i>.
This antlib file may be used in a build script as follows:
</p>
<blockquote>
<pre>
<typedef file="sample.xml"/>
</pre>
</blockquote>
<p>
The other attributes of <code><typedef></code> may be used as well.
For example, assuming that the <i>sample.xml</i> is in a jar
file <i>sample.jar</i> also containing the classes, the
following build fragment will define the <i>if</i> and <i>scriptpathmapper</i>
tasks/types and place them in the namespace uri <i>samples:/acme.org</i>.
</p>
<blockquote>
<pre>
<typedef resource="org/acme/ant/sample.xml"
uri="samples:/acme.org"/>
</pre>
</blockquote>
<p>
The definitions may then be used as follows:
</p>
<blockquote>
<pre>
<sample:if valuetrue="${props}" xmlns:sample="samples:/acme.org">
<sample:scriptpathmapper language="beanshell">
some bean shell
</sample:scriptpathmapper>
</sample:if>
</pre>
</blockquote>
<h3><a name="antlibnamespace">Antlib namespace</a></h3>
<p>
The name space URIs with the pattern <b>antlib:<i>java package</i></b>
are given special treatment.
</p>
<p>
When ant encounters a element with a namespace URI with this pattern, it
will check to see if there is a resource of the name <i>antlib.xml</i> in
the package directory in the default classpath.
</p>
<p>
For example, assuming that the file <i>antcontrib.jar</i> has been placed
in the directory <i>${ant.home}/lib</i> and it contains the resource
<i>net/sf/antcontrib/antlib.xml</i> which has all antcontrib's definitions
defined, the following build file will automatically load the antcontrib
definitions at location <i>HERE</i>:
</p>
<blockquote>
<pre>
<project default="deletetest" xmlns:antcontrib="antlib:net.sf.antcontrib">
<macrodef name="showdir">
<attribute name="dir"/>
<sequential>
<antcontrib:shellscript shell="bash"> <!-- HERE -->
ls -Rl @{dir}
</antcontrib:shellscript>
</sequential>
</macrodef>
<target name="deletetest">
<delete dir="a" quiet="yes"/>
<mkdir dir="a/b"/>
<touch file="a/a.txt"/>
<touch file="a/b/b.txt"/>
<delete>
<fileset dir="a"/>
</delete>
<showdir dir="a"/>
</target>
</project>
</pre>
</blockquote>
<p>
The requirement that the resource is in the default classpath
may be removed in future versions of Ant.</p>
</p>
<h3><a name="loadFromInside">Load antlib from inside of the buildfile</a></h3>
<p>
If you want to seperate the antlib from your local Ant installation, e.g. because you
want to hold that jar in your projects SCM system, you have to specify a classpath, so
that Ant could find that jar. The best solution is loading the antlib with <tt><taskdef></tt>.
</p>
<blockquote>
<pre>
<project xmlns:<font color="green">antcontrib</font>="<font color="red">antlib:net.sf.antcontrib</font>">
<taskdef uri="<font color="red">antlib:net.sf.antcontrib</font>"
resource="net/sf/antcontrib/antlib.xml"
classpath="path/to/ant-contrib.jar"/>
<target name="iterate">
<<font color="green">antcontrib</font>:for param="file">
<fileset dir="."/>
<sequential>
<echo message="- @{file}"/>
</sequential>
</antcontrib:for>
</target>
</project>
</pre>
</blockquote>
<h3><a name="currentnamespace">Current namespace</a></h3>
<p>
Definitions defined in antlibs may be used in antlibs. However
the namespace that definitions are placed in are dependent on
the <code><typedef></code> that uses the antlib. To deal with this
problem, the definitions are placed in the namepace URI <i>ant:current</i>
for the duration of the antlib execution.
For example the following antlib defines the task <code><if></code>, the
type <code><isallowed></code> and a macro
<code><ifallowed></code> that makes use of the task and type:
</p>
<blockquote>
<pre>
<antlib xmlns:current="ant:current">
<taskdef name="if" classname="org.acme.ant.If"/>
<typedef name="isallowed" classname="org.acme.ant.Isallowed"/>
<macrodef name="ifallowed">
<attribute name="action"/>
<element name="do"/>
<sequential>
<current:if>
<current:isallowed test="@{action}"/>
<current:then>
<do/>
</current:then>
</current:if>
</sequential>
</macrodef>
</antlib>
</pre>
</blockquote>
<h3>Other examples and comments</h3>
<p>
Antlibs may make use of other antlibs.
</p>
<p>
As the names defined in the antlib are in the namespace uri as
specified by the calling <code><typedef></code> or by automatic element
resolution, one may reuse names from core ant types and tasks,
provided the caller uses a namespace uri. For example, the
following antlib may be used to define defaults for various
tasks:
</p>
<blockquote>
<pre>
<antlib xmlns:antcontrib="antlib:net.sf.antcontrib">
<presetdef name="javac">
<javac deprecation="${deprecation}"
debug="${debug}"/>
</presetdef>
<presetdef name="delete">
<delete quiet="yes"/>
</presetdef>
<presetdef name="shellscript">
<antcontrib:shellscript shell="bash"/>
</presetdef>
</antlib>
</pre>
</blockquote>
<p>
This may be used as follows:
</p>
<blockquote>
<pre>
<project xmlns:local="localpresets">
<typedef file="localpresets.xml" uri="localpresets"/>
<local:shellscript>
echo "hello world"
</local:shellscript>
</project>
</pre>
</blockquote>
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