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https://issues.apache.org/jira/browse/MPH-220?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17906425#comment-17906425
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Nils Breunese commented on MPH-220:
-----------------------------------

This seems to work indeed:

{code}
❯ mvn --raw-streams -q help:evaluate -Dexpression=project.version -DforceStdout
1.0.0-SNAPSHOT
{code}

Should this become the documented example for Maven 4 in the Maven Help Plugin 
docs at https://maven.apache.org/plugins/maven-help-plugin/evaluate-mojo.html 
then?

> Evaluating an expression for use in a script fails on Maven 4.0.0-rc-1
> ----------------------------------------------------------------------
>
>                 Key: MPH-220
>                 URL: https://issues.apache.org/jira/browse/MPH-220
>             Project: Maven Help Plugin
>          Issue Type: Bug
>          Components: evaluate
>    Affects Versions: 3.5.1
>            Reporter: Nils Breunese
>            Priority: Major
>
> https://maven.apache.org/plugins/maven-help-plugin/evaluate-mojo.html shows 
> that to use the value of an expression in a script, you can use this:
> {code}
> mvn help:evaluate -Dexpression=project.version -q -DforceStdout
> {code}
> I use a variant of this in a project and it works fine with Maven 3.9.9, but 
> when I try it with Maven 4.0.0-rc-1, I no longer get the expected output.
> Here is a small reproducer POM:
> {code}
> <?xml version="1.0" encoding="UTF-8"?>
> <project xmlns="http://maven.apache.org/POM/4.0.0";
>          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";
>          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 
> http://maven.apache.org/xsd/maven-4.0.0.xsd";>
>   <modelVersion>4.0.0</modelVersion>
>   <groupId>com.example</groupId>
>   <artifactId>foo</artifactId>
>   <version>${revision}</version>
>   <packaging>pom</packaging>
>   <properties>
>     <revision>1.0.0-SNAPSHOT</revision>
>   </properties>
>   <build>
>     <plugins>
>       <plugin>
>         <groupId>org.apache.maven.plugins</groupId>
>         <artifactId>maven-help-plugin</artifactId>
>         <version>3.5.1</version>
>       </plugin>
>     </plugins>
>   </build>
> </project>
> {code}
> This returns {{1.0.0-SNAPSHOT}} with Maven 3.9.9:
> {code}
> ❯ mvn help:evaluate -Dexpression=project.version -q -DforceStdout
> 1.0.0-SNAPSHOT
> {code}
> But there is no output with Maven 4.0.0-rc-1:
> {code}
> ❯ mvn help:evaluate -Dexpression=project.version -q -DforceStdout
> {code}
> Note that when I omit the {{-q}} flag, then I do see the expected version in 
> the output, but that output is of course not usable in an automated script.



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