The Unset task provides easier access to one of the most used use cases of Variable, the ability to unset a property. By design, Ant properties are immutable, but sometimes it is handy to set a property to a new value.
To use this task in your build files, include a task definition like this:
<taskdef name="unset" classname="ise.antelope.tasks.Unset"/>
Table 8.1. Unset Task Attributes
| Attribute | Description | Default | Required |
|---|---|---|---|
| name | The name of the property to unset. | None | Yes, unless 'file' is used. |
| file | The name of a property file. All properties references in the file will be unset. This means you can load a bunch of properties from a file, then unset them all with a single line. | None | Yes, unless 'name' is used. |
Example:
<project name="unset_example" basedir=".">
<taskdef resource="ise/antelope/tasks/antlib.xml"/>
<property name="x" value="6"/>
<echo>original value = ${x}</echo>
<unset name="x"/>
<echo>unset: ${x}</echo>
<property name="x" value="hello"/>
<echo>new value = ${x}</echo>
</project>
$ ant -f unset_example.xml
Buildfile: unset_example.xml
[echo] original value = 6
[echo] unset: ${x}
[echo] new value = hello
BUILD SUCCESSFUL
Total time: 0 seconds