I use the <if> from ant-contrib combined with antcall or antcallback to have more flexibility on calling targets.

I use properties like ${nocvs} to not use CVS, even when the target is executed (again using <if> or unless)



I have unless properties for CVS, junit, javadoc, compile .....



In your case:

  <target name="checkout-sources" depends="other stuff" unless="nocvs">

    <!-- takes several minutes -->



In "other stuff" you have to introduce other unless properties probably.



Now you run

ant -Drelease.number=... -Dnocvs=true target1"



whil you run target2 this way



ant -Drelease.number=... target2"





-----Ursprüngliche Nachricht-----
Von: Niklas Matthies [mailto:ml_ant-user@(protected)]
Gesendet: Mittwoch, 18. August 2010 00:35
An: user@(protected)
Betreff: Conditional target problem



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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