I know ant is supposed to be follow a declarative style rather than a
procedural style. But what is wrong with writing scripts using the 'if' task in
conjunction with the ant-call task?
like the below example
<target name="determine-release-number"<if> <not> <isset
property="release.number"/> </not> <then> <ant-call
target="checkout-sources"/> </then> </if>
--- On Tue, 8/17/10, Vimil Saju <vimils...@yahoo.com> wrote:
From: Vimil Saju <vimils...@yahoo.com>
Subject: Re: Conditional target problem
To: "Ant Users List" <user@ant.apache.org>
Date: Tuesday, August 17, 2010, 4:20 PM
I know ant is supposed to be declarative language as opposed to a procedural
one, but whats wrong with using the 'if' task provided with ant-contrib along
with "ant-call" task? Wont it make ant-scripts more readable
something like this
<if>
--- On Tue, 8/17/10, Niklas Matthies <ml_ant-u...@nmhq.net> wrote:
From: Niklas Matthies <ml_ant-u...@nmhq.net>
Subject: Conditional target problem
To: user@ant.apache.org
Date: Tuesday, August 17, 2010, 3:35 PM
We have something like the following (target bodies omitted):
<target name="checkout-sources" depends="other stuff">
<!-- takes several minutes -->
<target name="determine-release-number"
depends="checkout-sources" unless="release.number">
<!-- determines release.number from sources -->
<target name="target1" depends="determine-release-number">
<!-- needs release.number -->
<target name="target2" depends="checkout-sources, target1">
<!-- needs sources and target1 -->
The problem: "ant -Drelease.number=... target1" causes
checkout-sources (and its dependencies) to be executed although there
is no need for it, as release.number is already defined.
We can't put the unless="release.number" on checkout-sources (and its
dependencies) because it would break target2 when release.number is
predefined.
We can't make checkout-sources a macro (called both by target2 and by
determine-release-number) because of all its dependencies, and also
because an up-to-date check on it is highly non-trivial, so in the
target2 case it might end up being executed twice.
We _could_ duplicate the body and the dependencies of checkout-sources
into determine-release-number (and remove the latter's dependency on
checkout-sources), but I'd have to do that for quite a number of the
dependencies as well, as they contribute to the expensiveness of
checkout-sources. The result would be a lot of redundancy, effectively
duplicating a dependency subgraph.
Is there a way to solve the problem, within a single Ant instance,
without creating redundancies?
-- Niklas Matthies
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