trunk/docs/manual/OptionalTasks/script.html - ant - Git at Google

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 <html>

 <head>
 <meta http-equiv="Content-Language" content="en-us"></meta>
 <link rel="stylesheet" type="text/css" href="../stylesheets/style.css">
 <title>Script Task</title>
 </head>

 <body>

 <h2><a name="script">Script</a></h2>
 <h3>Description</h3>
   <p>Execute a script in a
     <a href="http://jakarta.apache.org/bsf" target="_top">Apache BSF</a>
     or
     <a href="https://scripting.dev.java.net">JSR 223</a>  supported language.
   </p>
   <p><b>Note:</b>
     This task depends on external libraries not included in the Ant distribution.
     See <a href="../install.html#librarydependencies">Library Dependencies</a>
     for more information.
   </p>
   <p>
     The task may use the BSF scripting manager or the JSR 223 manager that
     is included in JDK6 and higher. This is controlled by the <code>manager</code>
     attribute. The JSR 223 scripting manager is indicated by "javax".
   </p>
   <p>All items (tasks, targets, etc) of the running project are
     accessible from the script, using either their <code>name</code> or
     <code>id</code> attributes (as long as their names are considered
     valid Java identifiers, that is).
     This is controlled by the "setbeans" attribute of the task.
     The name "project" is a pre-defined reference to the Project, which can be
     used instead of the project name. The name "self" is a pre-defined reference to the actual
     <code>&lt;script&gt;</code>-Task instance.<br>From these objects you have access to the Ant Java API, see the
 <a href="../api/index.html">JavaDoc</a> (especially for
 <a href="../api/org/apache/tools/ant/Project.html">Project</a> and
 <a href="../api/org/apache/tools/ant/taskdefs/optional/Script.html">Script</a>) for more information.</p>
 <p>If you are using JavaScript under BSF, a good resource is <a target="_blank" href="http://www.mozilla.org/rhino/doc.html">
 http://www.mozilla.org/rhino/doc.html</a> as we are using their JavaScript interpreter.</p>
 <p>Scripts can do almost anything a task written in Java could do.</p>
 <p>Rhino provides a special construct - the <i>JavaAdapter</i>. With that you can
 create an object which implements several interfaces, extends classes and for which you
 can overwrite methods. Because this is an undocumented feature (yet), here is the link
 to an explanation: <a href="http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=UTF-8&newwindow=1&frame=right&th=610d2db45c0756bd&seekm=391EEC3C.5236D929%40yahoo.com#link2">
 Groups@Google: "Rhino, enum.js, JavaAdapter?"</a> by Norris Boyd in the newsgroup
 <i>netscape.public.mozilla.jseng</i>.</p>


 <h3>Parameters</h3>
 <table border="1" cellpadding="2" cellspacing="0">
   <tr>
     <td valign="top"><b>Attribute</b></td>
     <td valign="top"><b>Description</b></td>
     <td align="center" valign="top"><b>Required</b></td>
   </tr>
   <tr>
     <td valign="top">language</td>
     <td valign="top">The programming language the script is written in.
       Must be a supported Apache BSF or JSR 223 language</td>
     <td valign="top" align="center">Yes</td>
   </tr>
   <tr>
     <td valign="top">manager</td>
     <td valign="top">
       <em>Since: Ant 1.7. </em>
       The script engine manager to use. This can have
       one of three values ("auto", "bsf" or "javax").
       The default value is "auto".
       <dl>
         <li>"bsf" use the BSF scripting manager to run
           the language.</li>
         <li>"javax" use the <em>javax.scripting</em> manager
           to run the language. (This will only work for JDK6 and higher).</li>
         <li>"auto" use the BSF engine if it exists,
           otherwise use the <em>javax.scripting</em> manager.</li>
       </dl>
     </td>
     <td valign="top" align="center">No</td>
   </tr>
   <tr>
     <td valign="top">src</td>
     <td valign="top">The location of the script as a file, if not inline</td>
     <td valign="top" align="center">No</td>
   </tr>
   <tr>
     <td valign="top">setbeans</td>
     <td valign="top">
       This attribute controls whether to set variables for
       all properties, references and targets in the running script.
       If this attribute is false, only the the "project" and "self" variables are set.
       If this attribute is true all the variables are set. The default value of this
       attribute is "true".  <em>Since Ant 1.7</em>
     </td>
     <td valign="top" align="center">No</td>
   </tr>
   <tr>
     <td valign="top">classpath</td>
     <td valign="top">
       The classpath to pass into the script. <em>Since Ant 1.7</em>
     </td>
     <td align="center" valign="top">No</td>
   </tr>
   <tr>
     <td valign="top">classpathref</td>
     <td valign="top">The classpath to use, given as a
        <a href="../using.html#references">reference</a> to a path defined elsewhere.
     <em>Since Ant 1.7</em></td>
     <td align="center" valign="top">No</td>
   </tr>
 </table>
 <h3>Parameters specified as nested elements</h3>
 <h4>classpath</h4>
   <p><em>Since Ant 1.7</em></p>
 <p>
   <code>Script</code>'s <code>classpath</code> attribute is a
   <a href="../using.html#path">path-like structure</a> and can also be set via a nested
   <code>&lt;classpath&gt;</code> element.
   <p>
     If a classpath is set, it will be used as the current thread
     context classloader, and
     as the classloader given to the BSF manager.
     This means that it can be used to specify
     the classpath containing the language implementation for BSF
     or for JSR 223 managers.
     This can be useful if one wants
     to keep ${user.home}/.ant/lib free of lots of scripting language
     specific jar files.
   </p>
   <p>
     <b>NB: (Since Ant 1.7.1)</b>
     This classpath <em>can</em> be used to
     specify the location of
     the BSF jar file and/or languages
     that have engines in the BSF jar file. This includes the
     javascript, jython, netrexx and jacl languages.
   </p>
 </p>
 <h3>Examples</h3>
 The following snippet shows use of five different languages:
   <blockquote><pre>
     &lt;property name="message" value="Hello world"/&gt;

     &lt;script language="groovy"&gt;
       println("message is " + message)
     &lt;/script&gt;

     &lt;script language="beanshell"&gt;
       System.out.println("message is " + message);
     &lt;/script&gt;

     &lt;script language="judoscript"&gt;
         println 'message is ', message
     &lt;/script&gt;

     &lt;script language="ruby"&gt;
         print 'message is ', $message, "\n"
     &lt;/script&gt;

     &lt;script language="jython"&gt;
 print "message is %s" % message
     &lt;/script&gt;
 </pre>
   </blockquote>
   <p>
   Note that for the <i>jython</i> example, the script contents <b>must</b>
   start on the first column.
   </p>
   <p>
     Note also that for the <i>ruby</i> example, the names of the set variables are prefixed
     by a '$'.
   <p>
     The following script shows a little more complicated jruby example:
   </p>
   <blockquote><pre>
 &lt;script language="ruby"&gt;
   xmlfiles = Dir.new(".").entries.delete_if { |i| ! (i =~ /\.xml$/) }
   xmlfiles.sort.each { |i| $self.log(i) }
 &lt;/script&gt;
 </pre>
   </blockquote>
   <p>
     The same example in groovy is:
   </p>
   <blockquote><pre>
 &lt;script language="groovy"&gt;
   xmlfiles = new java.io.File(".").listFiles().findAll{ it =~ "\.xml$"}
   xmlfiles.sort().each { self.log(it.toString())}
 &lt;/script&gt;
 </pre>
   </blockquote>
   <p>
     The following example shows the use of classpath to specify the location
     of the beanshell jar file.
   </p>
   <blockquote><pre>
 &lt;script language="beanshell" setbeans="true"&gt;
   &lt;classpath&gt;
     &lt;fileset dir="${user.home}/lang/beanshell" includes="*.jar" /&gt;
   &lt;/classpath&gt;
   System.out.println("Hello world");
 &lt;/script&gt;
 </pre>
   </blockquote>
   <p>
     The following script uses javascript to create a number of
     echo tasks and execute them.
   </p>
 <blockquote><pre>
 &lt;project name=&quot;squares&quot; default=&quot;main&quot; basedir=&quot;.&quot;&gt;

   &lt;target name=&quot;main&quot;&gt;

     &lt;script language=&quot;javascript&quot;&gt; &lt;![CDATA[

       for (i=1; i&lt;=10; i++) {
         echo = squares.createTask(&quot;echo&quot;);
         echo.setMessage(i*i);
         echo.perform();
       }

     ]]&gt; &lt;/script&gt;

   &lt;/target&gt;

 &lt;/project&gt;
 </pre></blockquote>
 <p>generates</p>
 <blockquote><pre>
 main:
 1
 4
 9
 16
 25
 36
 49
 64
 81
 100

 BUILD SUCCESSFUL
 </pre></blockquote>

 <p>Now a more complex example using the Java API and the Ant API. The goal is to list the
 filesizes of all files a <code>&lt;fileset/&gt;</code> caught.</p>
 <blockquote><pre>

 &lt;?xml version="1.0" encoding="ISO-8859-1"?&gt;
 &lt;project name="<font color=blue>MyProject</font>" basedir="." default="main"&gt;

   &lt;property name="fs.dir" value="src"/&gt;
   &lt;property name="fs.includes" value="**/*.txt"/&gt;
   &lt;property name="fs.excludes" value="**/*.tmp"/&gt;

   &lt;target name="main"&gt;
     &lt;script language="javascript"&gt; &lt;![CDATA[

       // import statements
       <font color=blue>// importPackage(java.io)</font>;
       <font color=blue>importClass(java.io.File)</font>;

       // Access to Ant-Properties by their names
       dir      = <font color=blue>project</font>.getProperty("fs.dir");
       includes = <font color=blue>MyProject</font>.getProperty("fs.includes");
       excludes = <font color=blue>self.getProject()</font>  .<font color=blue>getProperty("fs.excludes")</font>;

       // Create a &lt;fileset dir="" includes=""/&gt;
       fs = project.<font color=blue>createDataType("fileset")</font>;
       fs.setDir( new File(dir) );
       <font color=blue>fs.setIncludes(includes)</font>;
       fs.setExcludes(excludes);

       // Get the files (array) of that fileset
       ds = fs.getDirectoryScanner(project);
       srcFiles = ds.getIncludedFiles();

       // iterate over that array
       for (i=0; i&lt;srcFiles.length; i++) {

         // get the values via Java API
         var basedir  = fs.getDir(project);
         var filename = srcFiles[i];
         var file = <font color=blue>new File(basedir, filename)</font>;
         var size = file.length();

         // create and use a Task via Ant API
         echo = MyProject.<font color=blue>createTask("echo")</font>;
         echo.setMessage(filename + ": " + size + " byte");
         echo.<font color=blue>perform()</font>;
       }
     ]]&gt;&lt;/script&gt;
   &lt;/target&gt;
 &lt;/project&gt;
 </pre></blockquote>
 <p>We want to use the Java API. Because we don't want always typing the package signature
 we do an import. Rhino knows two different methods for import statements: one for packages
 and one for a single class. By default only the <i>java</i> packages are available, so
 <i>java.lang.System</i> can be directly imported with <code>importClass/importPackage</code>.
 For other packages you have to prefix the full classified name with <i>Packages</i>.
 For example Ant's <i>FileUtils</i> class can be imported with
 <code>importClass(<b>Packages</b>.org.apache.tools.ant.util.FileUtils)</code>
 <br>
 The <code>&lt;script&gt;</code> task populates the Project instance under
 the name <i>project</i>, so we can use that reference. Another way is to use its given name
 or getting its reference from the task itself.<br>
 The Project provides methods for accessing and setting properties, creating DataTypes and
 Tasks and much more.<br>
 After creating a FileSet object we initialize that by calling its set-methods. Then we can
 use that object like a normal Ant task (<code>&lt;copy&gt;</code> for example).<br>
 For getting the size of a file we instantiate a <code>java.io.File</code>. So we are using
 normal Java API here.<br>
 Finally we use the <code>&lt;echo&gt;</code> task for producing the output. The task is not executed by
 its execute() method, because the perform() method (implemented in Task itself) does the
 appropriate logging before and after invoking execute().
 </p>
 <p>
   Here is an example of using beanshell to create an ant
   task. This task will add filesets and paths to a referenced
   path. If the path does not exist, it will be created.
 </p>
 <blockquote><pre>
 &lt;!--
        Define addtopath task
  --&gt;
 &lt;script language="beanshell"&gt;
     import org.apache.tools.ant.Task;
     import org.apache.tools.ant.types.Path;
     import org.apache.tools.ant.types.FileSet;
     public class AddToPath extends Task {
         private Path path;
         public void setRefId(String id) {
             path = getProject().getReference(id);
             if (path == null) {
                 path = new Path(getProject());
                 getProject().addReference(id, path);
             }
         }
         public void add(Path c) {
             path.add(c);
         }
         public void add(FileSet c) {
             path.add(c);
         }
         public void execute() {
             // Do nothing
         }
     }
     project.addTaskDefinition("addtopath", AddToPath.class);
 &lt;/script&gt;
 </pre></blockquote>
   <p>
     An example of using this task to create a path
     from a list of directories (using antcontrib's
     <a href="http://ant-contrib.sourceforge.net/tasks/tasks/for.html">
       &lt;for&gt;</a> task) follows:
   </p>
 <blockquote><pre>
 &lt;path id="main.path"&gt;
   &lt;fileset dir="build/classes"/&gt;
 &lt;/path&gt;
 &lt;ac:for param="ref" list="commons,fw,lps"
         xmlns:ac="antlib:net.sf.antcontrib"&gt;
   &lt;sequential&gt;
     &lt;addtopath refid="main.path"&gt;
       &lt;fileset dir="${dist.dir}/@{ref}/main"
                includes="**/*.jar"/&gt;
     &lt;/addtopath&gt;
   &lt;/sequential&gt;
 &lt;/ac:for&gt;
 </pre></blockquote>

 </body>
 </html>
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	<html>

	<head>
	<meta http-equiv="Content-Language" content="en-us"></meta>
	<link rel="stylesheet" type="text/css" href="../stylesheets/style.css">
	<title>Script Task</title>
	</head>

	<body>

	<h2><a name="script">Script</a></h2>
	<h3>Description</h3>
	<p>Execute a script in a
	<a href="http://jakarta.apache.org/bsf" target="_top">Apache BSF</a>
	or
	<a href="https://scripting.dev.java.net">JSR 223</a> supported language.
	</p>
	<p><b>Note:</b>
	This task depends on external libraries not included in the Ant distribution.
	See <a href="../install.html#librarydependencies">Library Dependencies</a>
	for more information.
	</p>
	<p>
	The task may use the BSF scripting manager or the JSR 223 manager that
	is included in JDK6 and higher. This is controlled by the <code>manager</code>
	attribute. The JSR 223 scripting manager is indicated by "javax".
	</p>
	<p>All items (tasks, targets, etc) of the running project are
	accessible from the script, using either their <code>name</code> or
	<code>id</code> attributes (as long as their names are considered
	valid Java identifiers, that is).
	This is controlled by the "setbeans" attribute of the task.
	The name "project" is a pre-defined reference to the Project, which can be
	used instead of the project name. The name "self" is a pre-defined reference to the actual
	<code><script></code>-Task instance.<br>From these objects you have access to the Ant Java API, see the
	<a href="../api/index.html">JavaDoc</a> (especially for
	<a href="../api/org/apache/tools/ant/Project.html">Project</a> and
	<a href="../api/org/apache/tools/ant/taskdefs/optional/Script.html">Script</a>) for more information.</p>
	<p>If you are using JavaScript under BSF, a good resource is <a target="_blank" href="http://www.mozilla.org/rhino/doc.html">
	http://www.mozilla.org/rhino/doc.html</a> as we are using their JavaScript interpreter.</p>
	<p>Scripts can do almost anything a task written in Java could do.</p>
	<p>Rhino provides a special construct - the <i>JavaAdapter</i>. With that you can
	create an object which implements several interfaces, extends classes and for which you
	can overwrite methods. Because this is an undocumented feature (yet), here is the link
	to an explanation: <a href="http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=UTF-8&newwindow=1&frame=right&th=610d2db45c0756bd&seekm=391EEC3C.5236D929%40yahoo.com#link2">
	Groups@Google: "Rhino, enum.js, JavaAdapter?"</a> by Norris Boyd in the newsgroup
	<i>netscape.public.mozilla.jseng</i>.</p>



	<h3>Parameters</h3>
	<table border="1" cellpadding="2" cellspacing="0">
	<tr>
	<td valign="top"><b>Attribute</b></td>
	<td valign="top"><b>Description</b></td>
	<td align="center" valign="top"><b>Required</b></td>
	</tr>
	<tr>
	<td valign="top">language</td>
	<td valign="top">The programming language the script is written in.
	Must be a supported Apache BSF or JSR 223 language</td>
	<td valign="top" align="center">Yes</td>
	</tr>
	<tr>
	<td valign="top">manager</td>
	<td valign="top">
	<em>Since: Ant 1.7. </em>
	The script engine manager to use. This can have
	one of three values ("auto", "bsf" or "javax").
	The default value is "auto".
	<dl>
	<li>"bsf" use the BSF scripting manager to run
	the language.</li>
	<li>"javax" use the <em>javax.scripting</em> manager
	to run the language. (This will only work for JDK6 and higher).</li>
	<li>"auto" use the BSF engine if it exists,
	otherwise use the <em>javax.scripting</em> manager.</li>
	</dl>
	</td>
	<td valign="top" align="center">No</td>
	</tr>
	<tr>
	<td valign="top">src</td>
	<td valign="top">The location of the script as a file, if not inline</td>
	<td valign="top" align="center">No</td>
	</tr>
	<tr>
	<td valign="top">setbeans</td>
	<td valign="top">
	This attribute controls whether to set variables for
	all properties, references and targets in the running script.
	If this attribute is false, only the the "project" and "self" variables are set.
	If this attribute is true all the variables are set. The default value of this
	attribute is "true". <em>Since Ant 1.7</em>
	</td>
	<td valign="top" align="center">No</td>
	</tr>
	<tr>
	<td valign="top">classpath</td>
	<td valign="top">
	The classpath to pass into the script. <em>Since Ant 1.7</em>
	</td>
	<td align="center" valign="top">No</td>
	</tr>
	<tr>
	<td valign="top">classpathref</td>
	<td valign="top">The classpath to use, given as a
	<a href="../using.html#references">reference</a> to a path defined elsewhere.
	<em>Since Ant 1.7</em></td>
	<td align="center" valign="top">No</td>
	</tr>
	</table>
	<h3>Parameters specified as nested elements</h3>
	<h4>classpath</h4>
	<p><em>Since Ant 1.7</em></p>
	<p>
	<code>Script</code>'s <code>classpath</code> attribute is a
	<a href="../using.html#path">path-like structure</a> and can also be set via a nested
	<code><classpath></code> element.
	<p>
	If a classpath is set, it will be used as the current thread
	context classloader, and
	as the classloader given to the BSF manager.
	This means that it can be used to specify
	the classpath containing the language implementation for BSF
	or for JSR 223 managers.
	This can be useful if one wants
	to keep ${user.home}/.ant/lib free of lots of scripting language
	specific jar files.
	</p>
	<p>
	<b>NB: (Since Ant 1.7.1)</b>
	This classpath <em>can</em> be used to
	specify the location of
	the BSF jar file and/or languages
	that have engines in the BSF jar file. This includes the
	javascript, jython, netrexx and jacl languages.
	</p>
	</p>
	<h3>Examples</h3>
	The following snippet shows use of five different languages:
	<blockquote><pre>
	<property name="message" value="Hello world"/>

	<script language="groovy">
	println("message is " + message)
	</script>

	<script language="beanshell">
	System.out.println("message is " + message);
	</script>

	<script language="judoscript">
	println 'message is ', message
	</script>

	<script language="ruby">
	print 'message is ', $message, "\n"
	</script>

	<script language="jython">
	print "message is %s" % message
	</script>
	</pre>
	</blockquote>
	<p>
	Note that for the <i>jython</i> example, the script contents <b>must</b>
	start on the first column.
	</p>
	<p>
	Note also that for the <i>ruby</i> example, the names of the set variables are prefixed
	by a '$'.
	<p>
	The following script shows a little more complicated jruby example:
	</p>
	<blockquote><pre>
	<script language="ruby">
	xmlfiles = Dir.new(".").entries.delete_if { \|i\| ! (i =~ /\.xml$/) }
	xmlfiles.sort.each { \|i\| $self.log(i) }
	</script>
	</pre>
	</blockquote>
	<p>
	The same example in groovy is:
	</p>
	<blockquote><pre>
	<script language="groovy">
	xmlfiles = new java.io.File(".").listFiles().findAll{ it =~ "\.xml$"}
	xmlfiles.sort().each { self.log(it.toString())}
	</script>
	</pre>
	</blockquote>
	<p>
	The following example shows the use of classpath to specify the location
	of the beanshell jar file.
	</p>
	<blockquote><pre>
	<script language="beanshell" setbeans="true">
	<classpath>
	<fileset dir="${user.home}/lang/beanshell" includes="*.jar" />
	</classpath>
	System.out.println("Hello world");
	</script>
	</pre>
	</blockquote>
	<p>
	The following script uses javascript to create a number of
	echo tasks and execute them.
	</p>
	<blockquote><pre>
	<project name="squares" default="main" basedir=".">

	<target name="main">

	<script language="javascript"> <![CDATA[

	for (i=1; i<=10; i++) {
	echo = squares.createTask("echo");
	echo.setMessage(i*i);
	echo.perform();
	}

	]]> </script>

	</target>

	</project>
	</pre></blockquote>
	<p>generates</p>
	<blockquote><pre>
	main:
	1
	4
	9
	16
	25
	36
	49
	64
	81
	100

	BUILD SUCCESSFUL
	</pre></blockquote>

	<p>Now a more complex example using the Java API and the Ant API. The goal is to list the
	filesizes of all files a <code><fileset/></code> caught.</p>
	<blockquote><pre>

	<?xml version="1.0" encoding="ISO-8859-1"?>
	<project name="<font color=blue>MyProject</font>" basedir="." default="main">

	<property name="fs.dir" value="src"/>
	<property name="fs.includes" value="*/.txt"/>
	<property name="fs.excludes" value="*/.tmp"/>

	<target name="main">
	<script language="javascript"> <![CDATA[

	// import statements
	<font color=blue>// importPackage(java.io)</font>;
	<font color=blue>importClass(java.io.File)</font>;

	// Access to Ant-Properties by their names
	dir = <font color=blue>project</font>.getProperty("fs.dir");
	includes = <font color=blue>MyProject</font>.getProperty("fs.includes");
	excludes = <font color=blue>self.getProject()</font> .<font color=blue>getProperty("fs.excludes")</font>;

	// Create a <fileset dir="" includes=""/>
	fs = project.<font color=blue>createDataType("fileset")</font>;
	fs.setDir( new File(dir) );
	<font color=blue>fs.setIncludes(includes)</font>;
	fs.setExcludes(excludes);

	// Get the files (array) of that fileset
	ds = fs.getDirectoryScanner(project);
	srcFiles = ds.getIncludedFiles();

	// iterate over that array
	for (i=0; i<srcFiles.length; i++) {

	// get the values via Java API
	var basedir = fs.getDir(project);
	var filename = srcFiles[i];
	var file = <font color=blue>new File(basedir, filename)</font>;
	var size = file.length();

	// create and use a Task via Ant API
	echo = MyProject.<font color=blue>createTask("echo")</font>;
	echo.setMessage(filename + ": " + size + " byte");
	echo.<font color=blue>perform()</font>;
	}
	]]></script>
	</target>
	</project>
	</pre></blockquote>
	<p>We want to use the Java API. Because we don't want always typing the package signature
	we do an import. Rhino knows two different methods for import statements: one for packages
	and one for a single class. By default only the <i>java</i> packages are available, so
	<i>java.lang.System</i> can be directly imported with <code>importClass/importPackage</code>.
	For other packages you have to prefix the full classified name with <i>Packages</i>.
	For example Ant's <i>FileUtils</i> class can be imported with
	<code>importClass(<b>Packages</b>.org.apache.tools.ant.util.FileUtils)</code>
	<br>
	The <code><script></code> task populates the Project instance under
	the name <i>project</i>, so we can use that reference. Another way is to use its given name
	or getting its reference from the task itself.<br>
	The Project provides methods for accessing and setting properties, creating DataTypes and
	Tasks and much more.<br>
	After creating a FileSet object we initialize that by calling its set-methods. Then we can
	use that object like a normal Ant task (<code><copy></code> for example).<br>
	For getting the size of a file we instantiate a <code>java.io.File</code>. So we are using
	normal Java API here.<br>
	Finally we use the <code><echo></code> task for producing the output. The task is not executed by
	its execute() method, because the perform() method (implemented in Task itself) does the
	appropriate logging before and after invoking execute().
	</p>
	<p>
	Here is an example of using beanshell to create an ant
	task. This task will add filesets and paths to a referenced
	path. If the path does not exist, it will be created.
	</p>
	<blockquote><pre>
	<!--
	Define addtopath task
	-->
	<script language="beanshell">
	import org.apache.tools.ant.Task;
	import org.apache.tools.ant.types.Path;
	import org.apache.tools.ant.types.FileSet;
	public class AddToPath extends Task {
	private Path path;
	public void setRefId(String id) {
	path = getProject().getReference(id);
	if (path == null) {
	path = new Path(getProject());
	getProject().addReference(id, path);
	}
	}
	public void add(Path c) {
	path.add(c);
	}
	public void add(FileSet c) {
	path.add(c);
	}
	public void execute() {
	// Do nothing
	}
	}
	project.addTaskDefinition("addtopath", AddToPath.class);
	</script>
	</pre></blockquote>
	<p>
	An example of using this task to create a path
	from a list of directories (using antcontrib's
	<a href="http://ant-contrib.sourceforge.net/tasks/tasks/for.html">
	<for></a> task) follows:
	</p>
	<blockquote><pre>
	<path id="main.path">
	<fileset dir="build/classes"/>
	</path>
	<ac:for param="ref" list="commons,fw,lps"
	xmlns:ac="antlib:net.sf.antcontrib">
	<sequential>
	<addtopath refid="main.path">
	<fileset dir="${dist.dir}/@{ref}/main"
	includes="*/.jar"/>
	</addtopath>
	</sequential>
	</ac:for>
	</pre></blockquote>

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