A simple question about istrue of Ant.

[George2]

Hello everyone,

I have written the folllowing scripts, just want to output "Foo is true." when the property foo is set to true. But when using Eclipse to run the simple script, there are something wrong. Could anyone help to check what is the wrong with my shell scripts?

Source codes,

--------------------
<project default="Trivial">
<target name="Trivial">
<echo>Target trivial is running.</echo>
<property name="foo" value="true" />
<istrue value="${foo}" />
<then>
<echo> Foo is true. </echo>
</then>
</target>

</project>
--------------------

Error messages,
--------------------
Buildfile: C:\Documents and Settings\Admin\TestBuild.xml
Trivial:
[echo] Target trivial is running.
BUILD FAILED: C:\Documents and Settings\Admin\TestBuild.xml:5: Could not create task or type of type: istrue.

Ant could not find the task or a class this task relies upon.

This is common and has a number of causes; the usual
solutions are to read the manual pages then download and
install needed JAR files, or fix the build file:
- You have misspelt 'istrue'.
Fix: check your spelling.
- The task needs an external JAR file to execute
and this is not found at the right place in the classpath.
Fix: check the documentation for dependencies.
Fix: declare the task.
- The task is an Ant optional task and the JAR file and/or libraries
implementing the functionality were not found at the time you
yourself built your installation of Ant from the Ant sources.
Fix: Look in the ANT_HOME/lib for the 'ant-' JAR corresponding to the
task and make sure it contains more than merely a META-INF/MANIFEST.MF.
If all it contains is the manifest, then rebuild Ant with the needed
libraries present in ${ant.home}/lib/optional/ , or alternatively,
download a pre-built release version from apache.org
- The build file was written for a later version of Ant
Fix: upgrade to at least the latest release version of Ant
- The task is not an Ant core or optional task
and needs to be declared using <taskdef>.
- You are attempting to use a task defined using
<presetdef> or <macrodef> but have spelt wrong or not
defined it at the point of use

Remember that for JAR files to be visible to Ant tasks implemented
in ANT_HOME/lib, the files must be in the same directory or on the
classpath

Please neither file bug reports on this problem, nor email the
Ant mailing lists, until all of these causes have been explored,
as this is not an Ant bug.
Total time: 391 milliseconds
--------------------

thanks in advance,
George

[hooknc]

What the error is saying is that istrue is not an ant task that shipped with ant called "istrue". Which there isn't.

Try looking at ants "condition" task. It should be able to do what you need it to. You can then nest different types of condition elements in your "condition" task.

[George2]

hooknc,

What the error is saying is that istrue is not an ant task that shipped with ant called "istrue". Which there isn't.

Try looking at ants "condition" task. It should be able to do what you need it to. You can then nest different types of condition elements in your "condition" task.

Very valuable advice. Thanks!

regards,
George

[JustSomeGuy]

I have written the folllowing scripts, just want to output "Foo is true." when the property foo is set to true.

I'm trying to figure out how to do conditional execution without resorting to triggering targets everywhere, which is an antified version of goto. Here's a "goto" way to code your trivial example:

<project default="Trivial">

<property name="foo" value="true" />
<condition property="foo.true">
  <istrue value="${foo}"/>
</condition>

<target name="Trivial" depends="FooTrue,FooFalse">
<echo> Target trivial is running. </echo>
</target>

<target name="FooTrue" if="foo.true">
<echo> Foo is true. </echo>
</target>

<target name="FooFalse" unless="foo.true">
<echo> Foo is False. </echo>
</target>

</project>

What's the right way to do conditional execution without resorting to goto-ing a target with a depends= and if= clause?

[lybarger999]

What's the right way to do conditional execution without resorting to goto-ing a target with a depends= and if= clause?

Unfortunately, I think that's really the way it works. I write and maintain a lot of Ant code and I've had to resort to that (double target call with if and unless attributes) on a few occasions, and to writing custom ant tasks on others.

[vinu09]

--------------------
<project default="Trivial">
<target name="Trivial">
<echo>Target trivial is running.</echo>
<property name="foo" value="true" />
<istrue value="${foo}" />
<then>
<echo> Foo is true. </echo>
</then>
</target>

</project>
--------------------

I don't know whether this is too late , but I think there is genuine w
error here which says istrue can't be created as it is only valid inside <condition>

--Thanks
Vinu