Chapter 8. Unset Task

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

nameThe name of the property to unset.NoneYes, unless 'file' is used.
fileThe 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.NoneYes, unless 'name' is used.


<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>

$ ant -f unset_example.xml
Buildfile: unset_example.xml
     [echo] original value = 6
     [echo] unset: ${x}
     [echo] new value = hello

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