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From Stefan Bodewig <>
Subject Re: executing task for each file in file set
Date Tue, 12 Jun 2001 13:42:20 GMT
Peter Vogel <> wrote:

> I guess my point is that "bad practices" will happen, no matter what
> you do to prevent them.


> I challenge you to describe what a number of core and/or official
> optional tasks do without using the words for, each and if.

<echo> writes a message to Ant's logging system ;-)

Too me most tasks don't iterate but operate on sets, so I actually can
describe lots of tasks without using for in the sense of iteration:

<copy> copies a subset of the files given by the nested <fileset>
elements to the directory given in the todir attribute.  The subset
consists of those files that are newer than their corresponding

I know that the difference is just a small one, but I don't think
"iteration" when I talk about most tasks that accept filesets.

<execon> is a different beast.  As long as you say parallel="false",
we are talking about iteration, but this nice little parallel
attribute makes all the difference - you can transform a whole set of
files at once, without any iteration.  <execon> is a little more than
just <foreach> and <exec> nested into a single task.

This is not taking away anything from the argument that iteration can
be used to describe what you want to do.

>> In the meantime Ant has gathered some other quite popular tasks
>> that show what could be done with tasks - ejbjar and junit are
>> quite prominent examples.
> Haven't had a need for them yet.  I find it interesting that the
> examples most often cited for best meeting the goals of ant are not
> a part of the "core" and are very special-purpose (one is
> exclusively for use with WebLogic based projects, the other is based
> on a testing framework).

It has been a long time that <ejbjar> has been a Weblogic only tool,
it now supports a whole bunch of EJB containers.

JUnit is extremely popular (especially outside the open source
community).  Using Ant you can enforce a "no commit without running
the unit tests" policy - which possible with other build as well, but
gives you the integration for free.

> That said, they both look like good examples of appropriate use of
> ant's extensibility, there are others in the optional library that
> look like good examples of someone prefering to write a java task
> than to use the "<exec>" tag.

But even if they are just that, they provide a convenience layer on
top of exec for the uninitiated.  I've never used any source control
system apart from cvs and PVCS, but I think I could start using many
of them without reading the documentation - solely relying on the Ant

And then, things that start out as convenience layers may be expanded
to become much more than that at some point of time ...


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