Get value held in Ant element

Let's say I have a macrodef like so

<macrodef name="Test">
    <element name="someName"/>
    <sequential>
        <java classname="path_to_Test">
            <classpath> blah </classpath>
            <arg value="someText and {valueOfsomeName}"/>
        </java>
    </sequential>
</macrodef>

Then further down I have a target which uses this macrodef, like

<target name="testMacrodef">
    <Test>
        <someName value="someValue"/>
    </Test>
</target>

My question is, how do I get {valueOfsomeName} to be exactly the string someValue? I can't seem to get it to work at all.

Also, just for a bit of context, I can't just use an attribute tag instead of an element tag, as I need it to be an optional argument.

I've Googled for ages trying to find a solution for this; maybe there isn't one. But as far as I can see no one has asked this, and it doesn't seem to be covered well in the Ant documentation either, so if it's not possible is there a way of having an optional attribute?

EDIT: spelling

Use a simple echo if element has only text content, f.e. :

<macrodef name="Test">
 <element name="someName" optional="yes"/>
 <attribute name="foo" default="bar"/>
  <sequential>
   <echo>
    <someName/>
   </echo>
   <echo> @@{foo} => @{foo}</echo>
  </sequential>
</macrodef>

<Test>
 <someName>blablabla..</someName>
</Test>

output :

[echo]     
[echo]    blablabla..
[echo]  @{foo} => bar

otherwise for nested xml content use echoxml, f.e. :

<macrodef name="Test">
 <element name="someName" optional="yes"/>
 <attribute name="foo" default="bar"/>
  <sequential>
   <echoxml>
    <someName/>
   </echoxml>
   <echo> @@{foo} => @{foo}</echo>
  </sequential>
</macrodef>

<Test>
 <someName>
  <echo>blablabla..</echo>
 </someName>
</Test>

output :

<?xml version="1.0" encoding="UTF-8"?>
<echo>blablabla..</echo>
[echo]  @{foo} => bar

If you need the element values for further processing use echo / echoxml to file and loadfile afterwards.
--EDIT after comment --
Echo to file :

<macrodef name="Test">
 <element name="someName" optional="yes"/>
 <attribute name="foo" default="bar"/>
  <sequential>
   <echo file="somefile.txt">
    <someName/>
   </echo>
   <echo> @@{foo} => @{foo}</echo>
  </sequential>

or

<macrodef name="Test">
 <element name="someName" optional="yes"/>
 <attribute name="foo" default="bar"/>
  <sequential>
   <echoxml file="somefile.txt">
    <someName/>
   </echoxml>
   <echo> @@{foo} => @{foo}</echo>
  </sequential>

and use loadfile afterwards => creates property (= string) with content.
When using echoxml strip of the xml header with filterchain :

<loadfile srcfile=" ... " property="whatever">
 <filterchain>
  <headfilter lines="10" skip="1"/>
 </filterchain>
</loadfile>

Adapt the value of headfilter lines attribute to your needs.
Property whatever will have the value :

<echo>blablabla..</echo>