<?xml version="1.0" encoding="UTF-8"?>

<project name="test" default="build">

  <target name="build" >
    <if>
      <equals arg1="bar" arg2="bar" />
      <then>
        <property name="test.value" value="bar" />
        <echo>${test.value}</echo>
        <echo msg="${test.value}" />
      </then>
    </if>

    <property name="test.value" value="foo" override="true"/>
    <echo>${test.value}</echo>
    <echo msg="${test.value}" />
  </target>
</project>


output:
test > build:

     [echo] ${test.value}
     [echo] bar
     [echo] foo
     [echo] foo

BUILD FINISHED