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Message-ID: <879A5AD5DD0ED511891F0003473A9B5603CCC28E@Z011004>
From: Jan.Materne@rzf.fin-nrw.de
To: user@ant.apache.org
Subject: AW: AW: Conditional target execution based on prerequisite execut
	ion
Date: Tue, 18 Feb 2003 17:07:45 +0100
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Is <uptodate> your solution?


Jan Mat=E8rne


-----Urspr=FCngliche Nachricht-----
Von: Timothy Wall [mailto:twall@oculustech.com]
Gesendet am: Dienstag, 18. Februar 2003 17:02
An: Ant Users List
Betreff: Re: AW: Conditional target execution based on prerequisite
execution

The goal is not "run A before B" (although that may be a requirement).  =

The goal is "only run B if it is out of date".  Ant by default runs=20
(almost) everything all the time.

If B takes nonzero time to run, I *only* want it to run if B is "out of =

date".  Normally, a target would be considered out of date if
a) any of its "depends" is out of date (and thus gets run)
b) some other prerequisites are not satisfied (i.e. .java is newer than =

.class, or the .jar file is not yet built)

Some examples of standard conditional execution:

idl parsing/code generation: generate .java code only if .idl files=20
have been modified
jar file: only run jar if the class files it depends on have been=20
regenerated
java compiler: only compile if .java is newer than .class

The last is the only thing that I've seen ant handle automatically,=20
although I seem to have a knack for configuring things such that it=20
recompiles everything every time.

On a complex project, typically you'll have many smaller targets with=20
internal dependencies (and some with prerequisit targets as=20
dependencies) and several overall targets that primarily consist of=20
prerequisite target dependencies (a jar file or shared library, for=20
instance).

On Tuesday, February 18, 2003, at 10:23 AM, Jan.Materne@rzf.fin-nrw.de=20
wrote:

> When you use <target name=3D"B" depends=3D"A"/> the Ant framework =
will
> invoke A before B. Why setting a property?
>
> BTW the "onlyif" is <target if=3D"propertyname"/>
> There is a unless=3D"propertyname", too.
>
>
> Jan Mat=E8rne
>


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