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>

Answer 2

You can include different property files based on environments or the conditional variables. For example

    <echo>Building ${ant.project.name} on OS: ${os.name}-${os.arch}</echo>
<property file="build-${os.name}.properties" />

this would include a file named 'build-Windows 7.properties' or 'build-Linux.properties' depending on where the build is being run. Of course the property directive looks in the current directory as well as home directory. So the property file could be a part of the build source or in the home directory of the build account.

You can use the condition tag to generate part of the name of the property file as well to select