When you define an extension-point in an
Ant build file you can have it conditional by using
the if or unless attribute. On a target
the if/unless prevent it's tasks from being run. But an extension-point doesn't have any tasks to conditionally run, so what does
the condition do? My thought (which proved to be incorrect in
Ant 1.8.0) is it would prevent any tasks that extend
the extension-point from being run. Here is an example build script showing
the problem:
<project name = "ext-test"
default = "main">
<property name = "do.it" value = "false" />
<extension-point name = "init"/>
<extension-point name = "doit" depends = "init" if = "${do.it}" />
<target name = "extend-init" extensionOf = "init">
<echo message = "Doing extend-init." />
</target>
<target name = "extend-doit" extensionOf = "doit">
<echo message = "Do It! (${do.it})" />
</target>
<target name = "main" depends = "doit">
<echo message = "Doing main." />
</target>
</project>
Using
the command:
ant -v
Relults in:
Apache
Ant version 1.8.0 compiled on February 1 2010
Trying
the default build file: build.xml
Buildfile: /Users/bob/build.xml
Detected Java version: 1.6 in: /System/Library/Frameworks/JavaVM.framework/Versions/1.6.0/Home
Detected OS: Mac OS X
parsing buildfile /Users/bob/build.xml with URI = file:/Users/bob/build.xml
Project base dir set to: /Users/bob
parsing buildfile jar:file:/Users/bob/Documents/Development/3P-Tools/apache-ant-1.8.0/lib/ant.jar!/org/apache/tools/ant/antlib.xml with URI = jar:file:/Users/bob/Documents/Development/3P-Tools/apache-ant-1.8.0/lib/ant.jar!/org/apache/tools/ant/antlib.xml from a zip file
Build sequence for target(s) `main' is [extend-init, init, extend-doit, doit, main]
Complete build sequence is [extend-init, init, extend-doit, doit, main, ]
extend-init:
[echo] Doing extend-init.
init:
extend-doit:
[echo] Do It! (false)
doit:
Skipped because property 'false' not set.
main:
[echo] Doing main.
BUILD SUCCESSFUL
Total time: 0 seconds
You will notice
the target extend-doit is executed but
the extention-point itself is skipped. Since an extention-point doesn't have any tasks exactly what has been skipped? Any targets that depend on
the extention-point still get executed since a skipped target is a successful target. What is
the value of
the if/unless attributes on an extention-point?
