Adding stuff to tasks when plugin order is unknown

Help/Discuss
1

This is something that I mentioned in my talk at Greach this year. I said that this is the only way I know of doing in this and if someone knows a shorter way I would love to hear about it. René might have mentioned something, but if he did, I forgot. Therefore the question is now on the forum.

This is for the case where when I want to perform an additional action on a task in another plugin, but I do not know in which order plugins will be applied by a script author or whether it even will be applied.

// Let's say I want to do add something to 'jar' task, 
// but only if the 'java' plugin is applied.
// If is not applied, I don't want to do anything i.e. 
// I don't want my plugint to force-apply 'java'.

 try {
  Task t = project.tasks.getByName('jar')
  // Handle the case where task already exist
  if( t instanceof Jar) {
    do_something_with(t)   
}
} catch(UnknownTaskException) {
  // Handle case for when task is added at a later stage
  project.tasks.whenTaskAdded { Task t ->
  if (t.name == 'jar' && t instanceof Jar) {
    do_something_with(t)
  }
}

Is there any shorter way of writing the above?

2

Hey Schalk,

you could do something like this:

class MyPlugin implements Plugin<Project> {
    void apply(Project project) {
        project.plugins.withType(JavaPlugin) {
	     // add logic only if JavaPlugin is applied  (lazy evaluated)
             // no matter if applied after or before my own plugin
        }
     }
 }

cheers,
René

3

Hey René,

That’s find for something that ships woth Gradle, but what if I want to use ‘some.foo.bar.otherPlugin’ without creating a direct dependency on between my plugin and anotehr plugin.

For instance if I wanted to do something with John Engelman’s shadowJar, I can do

  project.tasks.whenTaskAdded { Task t ->
    if(t.class.superclass.name == 'com.github.jengelman.gradle.plugins.shadow.tasks.ShadowJar' && t.name=='shadowJar') {
      // Handle case for when shadowJar is added
    }
  }

which gets me around the dependency issue.

However I’m, not sure how I would achieve something similar using your example. I see there is a matching method, but it does not provide an option to provide an action as with withType.

4

You could use something like Class.forName() to check for the existence of the plugin on the classpath and conditionally then use plugins.withType() to register some configuration if the class exists.

1 Like
5

You could use

project.plugins.withId("com.github.johnrengelman.shadow") {
    //add your custom logic here
}

to avoid a direct compile dependency

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