Conditional property in Ant properties' file

Question

Is it possible to set a property value in Ant property files (as opposed to build.xml) in a conditional way? For example, if apache.root property is set - the my_property will be ${apache.root}/myapp, /var/www/myapp otherwise. If not, what would be the common practice - reusable build.xml files?

Answer 1

Use the condition task:

<project name="demo" default="run">

    <condition property="my_property" value="${apache.root}/myapp" else="/var/www/myapp">
        <isset property="apache.root"/>
    </condition>

    <target name="run">
        <echo message="my_property=${my_property}"/>
    </target>

</project>