RE: Can plugins be extended?

Plugins can't really be extended. What is most likely happening is that the metadata that tells plexus what to inject is not included in your plugin. There is a plugin/tool out there that supposedly allows you to extend plugins by merging the metadata, but I forget the name.

-----Original Message-----
From: walid joseph Gedeon [mailto:wgedeon@...]
Sent: Tuesday, April 29, 2008 10:37 AM
To: Maven Developers List
Subject: Can plugins be extended?

Hello all,
   After failing to customize the compiler pluging (by passing
<compileSourceRoots /> in the maven-compiler-plugin <configuration />); I've
went onto trying to extend the maven-compiler-plugin CompileMojo to just set
that variable.

It looks like I've missed something: the injected parameters of the super
classes are not being set (e.g. the parameter compilerId, or the component
compilerManager in AbstractCompilerMojo are null).
Is there a flag that enables injection of parameters in super classes? Or is
the issue something else?

Thanks :-)
Walid.

Note: a component definition maps the custom-compile goal to the <compile />
phase.

o====x maven-customcompile-plugin Mojo: x====o
/**
* @goal custom-compile
* @phase compile
* @requiresDependencyResolution runtime
*/
public class CustomCompilerMojo extends CompilerMojo {
   // ...

   /**
    * @parameter
    */
   private List<String> compileSourceRoots;

   protected List<String> getCompileSourceRoots()
   {
       return compileSourceRoots;
   }

   public void execute() throws MojoExecutionException,
CompilationFailureException
   {
       super.execute();
   }
}

o====x Project POM: x====o
<!-- ... -->
  <build>
    <plugins>
      <plugin>
        <groupId>fr.gedeon</groupId>
        <artifactId>maven-customcompile-plugin</artifactId>
        <extensions>true</extensions>
        <configuration>
          <compileSourceRoots>
            <directory>Dev/src/java</directory>
          </compileSourceRoots>
        </configuration>
      </plugin>
    </plugins>
  </build>

o====x Partial Trace: x====o
[DEBUG] Configuring mojo
'fr.gedeon:maven-customcompile-plugin:1.0-SNAPSHOT:custom-compile' -->
[DEBUG]   (f) compileSourceRoots = [Dev/src/java]
[DEBUG]   (f) project = org.apache.maven.project.MavenProject@82bcf39e
[DEBUG] -- end configuration --
[INFO] [bem:custom-compile]
[DEBUG] Using compiler 'null'.
>       ^ this is from getLog().debug( "Using compiler '" + compilerId +
"'." );
>         in AbstractCompilerMojo
[INFO]
------------------------------------------------------------------------
[ERROR] FATAL ERROR
[INFO]
------------------------------------------------------------------------
[INFO] null
[INFO]
------------------------------------------------------------------------
[DEBUG] Trace
java.lang.NullPointerException
        at
org.apache.maven.plugin.AbstractCompilerMojo.execute(AbstractCompilerMojo.java:267)
>          ^ I suppose this is compiler = compilerManager.getCompiler(
compilerId );
>            with compilerManager = null
        at
org.apache.maven.plugin.CompilerMojo.execute(CompilerMojo.java:114)
        at
org.apache.maven.plugin.CompileBemMojo.execute(CompileBemMojo.java:37)
...