Override ignored for property - ant

Question

Content of Build.xml File
<?xml version="1.0"?>
<taskdef resource="net/sf/antcontrib/antcontrib.properties" classpath="ant-contrib-0.6.jar"/>
<taskdef classpath="orangevolt-ant-tasks-1.3.2.jar" resource="com/orangevolt/tools/ant/taskdefs.properties"/>
<project name="initinstaller" default="all" basedir="." >
<target name="configure-server-types-module">
<property file="./installation.conf"/>
<echo message="${client.server.types}"/>
<if>
<not>
<contains string="${client.server.types}" substring="tomcat" />
</not>
<then>
<replaceregexp file="./installation.conf"
match="client.server.types=(.*)"
replace="client.server.types=\1tomcat,"
byline="true">
</replaceregexp>
</then>
</if>
</target>
<target name="all" depends="configure-server-types-module">
<property file="./installation.conf"/>
<echo message="${client.server.types}"/>
<if>
<not>
<contains string="${client.server.types}" substring="tomcat" />
</not>
<then>
<replaceregexp file="./installation.conf"
match="client.server.types=(.*)"
replace="client.server.types=\1tomcat,"
byline="true">
</replaceregexp>
</then>
</if>
</target>
Content of installation.conf : client.server.types=jboss,
Verbose Output :
Apache Ant version 1.8.1 compiled on April 30 2010
Trying the default build file: build.xml
Buildfile: D:\testing\build.xml
Detected Java version: 1.6 in: C:\Program Files\Java\jdk1.6.0_21\jre
Detected OS: Windows XP
parsing buildfile D:\testing\build.xml with URI = file:/D:/testing/build.xml
Project base dir set to: D:\testing
parsing buildfile jar:file:/C:/apache-ant-1.8.1/lib/ant.jar!/org/apache/tools/ant/antlib.xml with URI = jar:file:/C:/apache-ant-1.8.1/lib/ant.jar!/org/apache/tools/ant/antlib.xml from a zip file
dropping D:\testing\ant-contrib-0.6.jar from path as it doesn't exist
dropping D:\testing\orangevolt-ant-tasks-1.3.2.jar from path as it doesn't exist
Build sequence for target(s) `all' is [configure-server-types-module, all]
Complete build sequence is [configure-server-types-module, all, ]
configure-server-types-module:
[property] Loading D:\testing\installation.conf
[echo] jboss,
[replaceregexp] Replacing pattern 'client.server.types=(.*)' with
'client.server.types=\1tomcat,' in 'D:\testing\installation.conf' by line.
[replaceregexp] File has changed; saving the updated file
all:
[property] Loading D:\testing\installation.conf
**Override ignored for property "client.server.types"**
[echo] jboss,
[replaceregexp] Replacing pattern 'client.server.types=(.*)' with
'client.server.types=\1tomcat,' in 'D:\testing\installation.conf' by line.
[replaceregexp] File has changed; saving the updated file
BUILD SUCCESSFUL
Total time: 0 seconds
==============================================================
my question is that how i can override the ant property

Answer 1

Once an Ant property has been set its value cannot be changed.
Perhaps you could use the prefix attribute of the <property> task when you first load the properties file so that the property has a different name:
<target name="configure-server-types-module">
<property file="./installation.conf" prefix="temp."/>
<echo message="${temp.client.server.types}"/>
<if>
<not>
<contains string="${temp.client.server.types}" substring="tomcat" />
</not>
<then>
<replaceregexp file="./installation.conf"
match="client.server.types=(.*)"
replace="client.server.types=\1tomcat,"
byline="true">
</replaceregexp>
</then>
</if>
</target>
Note: I haven't tested this.
Then in the second target you can still use the proper name as that property has not been set yet.
(this solution only works with 3rd-party plugin ANT-contrib-library installed: ANT contrib Download)

Answer 2

If you're already using the Ant-Contrib jar as it seems from your example, you could change your property definition to a var (see http://ant-contrib.sourceforge.net/tasks/tasks/variable_task.html)

Answer 3

Use
<property name="x" value="6"/>
<echo>${x}</echo> <!-- will print 6 -->
<var name="x" unset="true"/>
<property name="x" value="12"/>
<echo>${x}</echo> <!-- will print 12 -->
It's work for my fine!