Ant - append a list of file names

Question

Greetings all,

I need to write an Ant target that appends together (comma-delimited) a list of '.jar' file names from a folder into a variable, which is later used as input to an outside utility. I am running into barriers of scope and immutability. I have access to ant-contrib, but unfortunately the version I am stuck with does not have access to the 'for' task. Here's what I have so far:

<target name="getPrependJars">
        <var name="prependJars" value="" />
        <foreach param="file" target="appendJarPath">
            <path>
                <fileset dir="${project.name}/hotfixes">
                    <include name="*.jar"/>
                </fileset>
            </path>         
        </foreach>

        <echo message="result ${prependJars}" />
    </target>

    <target name="appendJarPath">
        <if>
            <equals arg1="${prependJars}" arg2="" />
            <then>
                <var name="prependJars" value="-prependJars ${file}" />
            </then>
            <else>
                <var name="prependJars" value="${prependJars},${file}" />
            </else>
        </if>       
    </target>

It seems that 'appendJarPath' only modifies 'prependJars' within its own scope. As a test, I tried using 'antcallback' which works for a single target call, but does not help me very much with my list of files.

I realize that I am working somewhat against the grain, and lexical scope is desirable in the vast majority of instances, but i really would like to get this working one way or another. Does anybody have any creative ideas to solve this problem?

Thanks in advance!

Answer 1

I'd simply write a custom task in Java that (1) takes the folder name, (2) assembles the result string and (3) stores it to the ${prependJars} property.

In ant you just define the task (taskdef) and use like all other tasks afterwards.

I did it once when I was faced with a simliar problem and found that it was very, very easy.

Here's the tutorial.

Answer 2

If a system path format is useful to you, you can use the following:

<target name="getPrependJars">
    <path id="prepend.jars.path">
        <fileset dir="${project.name}/hotfixes">
            <include name="*.jar"/>
        </fileset>
    </path>         
    <property name="prependJars" value="${toString:jars.path}" />

    <echo message="result ${prependJars}" />
</target>

Answer 3

You might be able to use the pathconvert task, which allows you to specify the separator character as comma.

<target name="getPrependJars">
    <fileset id="appendJars" dir="${project.name}/hotfixes">
        <include name="*.jar" />
    </fileset>
    <pathconvert property="prependJars" refid="appendJars" pathsep="," />

    <echo message="prependJars: ${prependJars}" />
</target>