Passing optional path arguments to ant

Question

I have an ant task that uses an apply task to run a script on a group of files.

I have a directory structure resultant of something like this: mkdir -p a/{b,c,d,e}/f

Normally (if I pass no arguments), I would like ant to run on all fs. That is, if I called ant mytask, it should process: a/b/f, a/c/f, a/d/f, a/e/f. This already works using apply and patternsets.

However, when I pass it an optional argument called foo, it should only call the script on a/foo/f.

So if I called ant mytask -foo b, it should process a/b/f only, and not the others.

I have read this SO post, which explains ways of passing arguments, and I have looked at the ant documentation regarding properties, and conditionals. But I am still unable to piece them together in a way that works.

Also, I do not want to use one of the suggestions from the SO above which called for arguments like this:

<arg value="${arg0}"/>
<arg value="${arg1}"/>

I want to be able to call it as ant mytask -foo valueoffoo for any arbitrary foo.

Thanks.

---

I tried martin clayton's suggestion below and have code like:

<target name="mytask">
  <property name="foo" value="*" />
  <apply executable="perl">
    <arg value="somescript"/>
    <dirset id="them" dir="a">
      <include name="${foo}/*/f" />
    </dirset>
  </apply>
</target>

The above does what I want.

Note 1: In my actual code I use a patternset instead of dirset but it should work the same.

Note 2: In my original question I said the directory structure was a/{b,c,d,e}/f. It is in fact a bit more complicated, hence the * in the include above. I omitted that the first time around because it did not seem relevant.

Answer 1

You can do this - albeit with a slightly different command-line syntax - using a property 'override'.

First, in the buildfile, construct your fileset or dirset from a property foo, something like this:

<property name="foo" value="*" />
<dirset id="them" dir="a">
    <include name="${foo}/f" />
</dirset>

This will give you your default behaviour - processing all subdirectories of a that themselves have a subdirectory f.

Now, if you run Ant like this:

ant -Dfoo=d

Only directory a/d/f will be processed.

This works because Ant properties are not mutable - well, not normally anyway - so the command-line definition of foo prevents the one within the buildfile from being used.