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From Roger Vaughn <rvau...@seaconinc.com>
Subject Re: Immutable Properties in 1.1?
Date Thu, 20 Jul 2000 20:24:57 GMT
Bravo.  Basically this is like subroutines for Ant.  (I know, I know, it's
more like XSL templates, but still...)  This feature would be *very*
welcomed.  I wanted this for years in Make, and lamented even the repetition
I had to do in Ant.  So for me, make that

+1

Jesse Glick wrote:

> Roger Vaughn wrote:
> > I have to agree that the example given on the download page is worth
> > preventing, but I have been using redefined properties for perfectly
> > legitimate purposes - to simplify constructing sets of similar targets
> > in my builds.
>
> I should mention that I have done some work on an experimental patch to
> the core (I know, hisses) which should permit you to specify templates
> for targets rather than concrete targets. The syntax is pretty simple,
> using regular expressions (not ideal but simple to understand and very
> flexible):
>
> <project name="foo" default="echo-hello" basedir=".">
>   <target pattern="echo-(.*)">
>     <echo message="I say: $[1]"/>
>   </target>
> </project>
>
> This should print "I say: hello". In other words, the target is really a
> template; it is instantiated on demand and $[number] variables in
> substitutable places within the target body are replaced by the
> corresponding regex match strings. If you have used Perl, sed, etc. then
> the idea should be pretty clear. That example is dumb of course but more
> to the point:
>
> > <target name="jar1">
> >   <property name="jarfile" value="jar1.jar"/>
> >   <property name="includes" value="**/somefiles"/>
> >   <!-- some code that uses ${jarfile} and ${includes} -->
> > </target>
> >
> > <target name="jar2">
> >   <property name="jarfile" value="jar2.jar"/>
> >   <property name="includes" value="**/someotherfiles"/>
> >   <!-- some code that uses ${jarfile} and ${includes} -->
> > </target>
>
> This would become:
>
> <project name="xxx" basedir="." default="all-jars">
>   <target name="all-jars" depends="jar1,jar2"/>
>   <target pattern="jar([0-9]+)">
>     <echo message="Running target $[0]..."/>
>     <someJarTask jarfileToUse="jar$[1].jar"
>                  includeList="**/someotherfiles-$[1]"/>
>   </target>
> </project>
>
> No property mutation or copy-and-paste required. For those familiar with
> GNU make, this is similar to use of % patterns in make targets, except
> more flexible (regexps vs. shell patterns, and multiple match
> substrings). You can have as many templates as you need; the first one
> which matches a required target name will be used.
>
> I would appreciate any thoughts on whether people would find this sort
> of thing valuable, or if there is an obvious way to get the same effect
> with Ant as it is. I guess you can run an Ant sub-project but that seems
> rather cumbersome. Hopefully the syntax does not appear too wretched.
> One caveat: <script> will not see targets from template unless they had
> been instantiated anyway; I do not see any way around this.
>
> BTW implementation of this is a headache: can I suggest for the future
> that ProjectHelper parse the document, *then* go through and construct
> targets and tasks (depth-first-search from root)? That would greatly
> simplify changes like this (at the expense of a small increase in memory
> at runtime). It would also be helpful when running Ant embedded in some
> other tool (parse one, run many). Especially since properties are set
> while parsing, which seems sort of a hack.
>
> -Jesse
>
> --
> Jesse Glick   <mailto:Jesse.Glick@netbeans.com>
> NetBeans, Open APIs  <http://www.netbeans.org/>
> tel (+4202) 3300-9161 Sun Micro x49161 Praha CR


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