Delete Variables

   Variables are not like standard Ant properties, you can’t reference or change them unless you use the $var: shortcut explicitly. Regardless, sometimes you want to make sure you clean-up variables especially if you’ve created them as part of a macro definition because they will retain their values across macro invocations, sub-builds, targets, and even threads. Note that when you remove a variable, it is removed for everybody, not just the current project.

The easiest way to “delete” a variable, is to just set the variable to the empty string like:

<assign var="myvar" value=""/>

You can also use the <unassign> task which make the delete explicit for anyone reading the script at some later date.

<unassign var="myvar"/>
<unassign variables="thisvar,thatvar,othervar"/>

If you want to clear variables that were created to pass information back from a child project (like with the <call> task), turn the <assignimport>’s “ismove” option on like in following snippet line 11:

 1: <macrodef name="run-testsuites">
 2:   <attribute name="names"/>
 3:   <sequential>
 4:     <foreach i="suite" list="@{names}" tryeach="yes">
 5:       <echo message="Running Testsuite: ${suite}" level="info"/>
 6:       <call targets="setup,run,teardown" passthru="none">
 7:         <reference refid="test.fixture" torefid="context"/>
 8:         <property name="name" value="${suite}"/>
 9:         <property name="results.prefix" value="outputs."/>
10:       </call>
11:       <assignimport prefix="outputs." ismove="yes">
12:         <glob from="outputs.*" to="results.${suite}.*"/>
13:       </assignimport>
14:     </foreach>
15:   </sequantial>
16: </macrodef>

To verify that AntXtras really knows nothing about a particular variable you can use an assertion like so:

<assert varnotset="myvar" msg="The variable 'myvar' is undefined"/>