Mentioning workaround from #38040 re. eagerly evaluated properties.

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@359077 13f79535-47bb-0310-9956-ffa450edef68

docs/manual/CoreTasks/presetdef.html

@@ -146,6 +146,21 @@ called:
 [showmessage] message is 'Message 2'
 </pre>
      </blockquote>
+<p>
+It is possible to use a trick to evaluate properties when the definition is
+<em>made</em> rather than used. This can be useful if you do not expect some
+properties to be available in child builds run with
+<code>&lt;ant ... inheritall="false"&gt;</code>:
+</p>
+<blockquote><pre class="code">
+&lt;macrodef name="showmessage-presetdef"&gt;
+  &lt;attribute name="messageval"/&gt;
+  &lt;presetdef name="showmessage"&gt;
+    &lt;echo&gt;message is '@{messageval}'&lt;/echo&gt;
+  &lt;/presetdef&gt;
+&lt;/macrodef&gt;
+&lt;showmessage-presetdef messageval="${message}"/&gt;
+</pre></blockquote>
     <hr></hr>
     <p align="center">Copyright &copy; 2003-2005 Apache Software
       Foundation. All rights Reserved.</p>