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<title>MacroDef Task</title>
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<body>
<h2><a name="macrodef">MacroDef</a></h2>
<h3>Description</h3>
<p>
This defines a new task using a <code><sequential></code>
nested task as a template. Nested elements <code><attribute></code> and
<code><element></code> are used to specify attributes and elements of
the new task. These get substituted into the <code><sequential></code>
task when the new task is run.
</p>
<h3>Note</h3>
<p>
You can also use <i>prior defined</i> attributes for default-values in
other attributes. See the examples.
</p>
<p>
<em>since Apache Ant 1.6</em>
</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">name</td>
<td valign="top">The name of the new definition.</td>
<td valign="top" align="center">Yes</td>
</tr>
<tr>
<td valign="top">uri</td>
<td valign="top">
The uri that this definition should live in.
</td>
<td valign="top" align="center">No</td>
</tr>
<tr>
<td valign="top">description</td>
<td valign="top">A description of the macrodef
(for documentation purposes only).
</td>
<td valign="top" align="center">No</td>
</tr>
<tr>
<td valign="top">backtrace</td>
<td valign="top">
This controls the error traceback if there is an
error detected when running the macro. If this is
set to true, there will be an error trackback, if false
there will not be one. <em>Since Ant 1.7</em>.
</td>
<td valign="top" align="center">No; default <em>true</em></td>
</tr>
</table>
<h3>Parameters specified as nested elements</h3>
<h4>attribute</h4>
<p>
This is used to specify attributes of the new task. The values
of the attributes get substituted into the templated task.
The attributes will be required attributes unless a default
value has been set.
</p>
<p>
This attribute is placed in the body of the templated
task using a notation similar to the ant property notation
- @{attribute name}. (May be remembered as "put the substitution
AT this location").
</p>
<p>
The escape sequence @@ is used to escape @. This allows @{x} to be
placed in the text without substitution of x by using @@{x}.
This corresponds to the $$ escape sequence for properties.
</p>
<p>
The case of the attribute is ignored, so @{myAttribute} is treated the
same as @{MyAttribute}.
</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">name</td>
<td valign="top">The name of the new attribute</td>
<td valign="top" align="center">Yes</td>
</tr>
<tr>
<td valign="top">default</td>
<td valign="top">
The default value of the attribute.
</td>
<td valign="top" align="center">No</td>
</tr>
<tr>
<td valign="top">description</td>
<td valign="top">
This contains a description of the attribute.
<em>since ant 1.6.1</em>
</td>
<td valign="top" align="center">No</td>
</tr>
<tr>
<td valign="top">doubleexpanding</td>
<td valign="top">
Controls whether or not property references in the attribute are expanded twice or just once.
See the <a href="http://ant.apache.org/faq.html#macrodef-property-expansion">FAQ</a> for details.
<em>since Ant 1.8.3</em>
</td>
<td valign="top" align="center">No; default true</td>
</tr>
</table>
<h4>element</h4>
<p>
This is used to specify nested elements of the new task.
The contents of the nested elements of the task instance
are placed in the templated task at the tag name.
</p>
<p>
The case of the element name is ignored.
</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">name</td>
<td valign="top">The name of the element</td>
<td valign="top" align="center">Yes</td>
</tr>
<tr>
<td valign="top">optional</td>
<td valign="top">
If true this nested element is optional. Default is
false - i.e the nested element is required in
the new task.
</td>
<td valign="top" align="center">No</td>
</tr>
<tr>
<td valign="top">implicit</td>
<td valign="top">
If true this nested element is implicit. This means that
any nested elements of the macrodef instance will be placed
in the element indicated by the name of this element.
There can only be one element if an element is implicit.
The default value is false. <em>since ant 1.6.2</em>
</td>
<td valign="top" align="center">No</td>
</tr>
<tr>
<td valign="top">description</td>
<td valign="top">
This contains a description
informing the user what the contents of the element are expected to be.
<em>since ant 1.6.1</em>
</td>
<td valign="top" align="center">No</td>
</tr>
</table>
<h4>text</h4>
<p>
This is used to specify the treatment of text contents of the macro invocation.
If this element is not present, then any nested text in the macro invocation
will be an error. If the text element is present, then the name
becomes an attribute that gets set to the nested text of the macro invocation.
<em>Since ant 1.6.1.</em>
</p>
<p>
The case of the text name is ignored.
</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">name</td>
<td valign="top">The name of the text attribute</td>
<td valign="top" align="center">Yes</td>
</tr>
<tr>
<td valign="top">optional</td>
<td valign="top">
If true nested text in the macro is optional, default is "false".
</td>
<td valign="top" align="center">No</td>
</tr>
<tr>
<td valign="top">trim</td>
<td valign="top">
If true, the nested text is trimmed of white space,
default is "false".
</td>
<td valign="top" align="center">No</td>
</tr>
<tr>
<td valign="top">description</td>
<td valign="top">
This contains a description
informing the user what the nested text of the macro is expected
to be.
</td>
<td valign="top" align="center">No</td>
</tr>
</table>
<h3>Examples</h3>
<p>
The following example defined a task called testing and
runs it.
</p>
<blockquote>
<pre class=code>
<macrodef name="testing">
<attribute name="v" default="NOT SET"/>
<element name="some-tasks" optional="yes"/>
<sequential>
<echo>v is @{v}</echo>
<some-tasks/>
</sequential>
</macrodef>
<testing v="This is v">
<some-tasks>
<echo>this is a test</echo>
</some-tasks>
</testing>
</pre>
</blockquote>
<p>
The following fragment defines a task called <code><call-cc></code> which
take the attributes "target", "link" and "target.dir" and the
nested element "cc-elements". The body of the task
uses the <code><cc></code> task from the
<a href="http://ant-contrib.sourceforge.net/">ant-contrib</a> project.
</p>
<blockquote>
<pre class="code">
<macrodef name="call-cc">
<attribute name="target"/>
<attribute name="link"/>
<attribute name="target.dir"/>
<element name="cc-elements"/>
<sequential>
<mkdir dir="${obj.dir}/@{target}"/>
<mkdir dir="@{target.dir}"/>
<cc link="@{link}" objdir="${obj.dir}/@{target}"
outfile="@{target.dir}/@{target}">
<compiler refid="compiler.options"/>
<cc-elements/>
</cc>
</sequential>
</macrodef>
</pre>
</blockquote>
<p>
This then can be used as follows:
</p>
<blockquote>
<pre class="code">
<call-cc target="unittests" link="executable"
target.dir="${build.bin.dir}">
<cc-elements>
<includepath location="${gen.dir}"/>
<includepath location="test"/>
<fileset dir="test/unittest" includes = "**/*.cpp"/>
<fileset dir="${gen.dir}" includes = "*.cpp"/>
<linker refid="linker-libs"/>
</cc-elements>
</call-cc>
</pre>
</blockquote>
<p>
The following fragment shows <call-cc>, but this time
using an implicit element and with the link and target.dir arguments
having default values.
</p>
<blockquote>
<pre class="code">
<macrodef name="call-cc">
<attribute name="target"/>
<attribute name="link" default="executable"/>
<attribute name="target.dir" default="${build.bin.dir}"/>
<element name="cc-elements" implicit="yes"/>
<sequential>
<mkdir dir="${obj.dir}/@{target}"/>
<mkdir dir="@{target.dir}"/>
<cc link="@{link}" objdir="${obj.dir}/@{target}"
outfile="@{target.dir}/@{target}">
<compiler refid="compiler.options"/>
<cc-elements/>
</cc>
</sequential>
</macrodef>
</pre>
</blockquote>
<p>
This then can be used as follows, note that <cc-elements>
is not specified.
</p>
<blockquote>
<pre class="code">
<call-cc target="unittests">
<includepath location="${gen.dir}"/>
<includepath location="test"/>
<fileset dir="test/unittest" includes = "**/*.cpp"/>
<fileset dir="${gen.dir}" includes = "*.cpp"/>
<linker refid="linker-libs"/>
</call-cc>
</pre>
</blockquote>
<p>
The following shows the use of the <code>text</code> element.
</p>
<blockquote>
<pre class="code">
<macrodef name="echotest">
<text name="text"/>
<sequential>
<echo>@{text}</echo>
</sequential>
</macrodef>
<echotest>
Hello world
</echotest>
</pre>
</blockquote>
<p>
The following uses a prior defined attribute for setting the
default value of another. The output would be
<tt>one=test two=test</tt>. If you change the order of lines
*1 and *2 the output would be <tt>one=test two=@{one}</tt>,
because while processing the <i>two</i>-line the value for
<i>one</i> is not set.
</p>
<blockquote>
<pre class="code">
<macrodef name="test">
<attribute name="one"/> <b>*1</b>
<attribute name="two" default="@{one}"/> <b>*2</b>
<sequential>
<echo>one=@{one} two=@{two}</echo>
</sequential>
</macrodef>
<test one="test"/>
</pre>
</blockquote>
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