KotlinLoader

Kotlin PluginLoader for Spigot.

KotlinLoader

Kotlin is a wonderful growing programming language with support for the JVM. This allows us to write Minecraft Plugins in Kotlin. While this works fine, it does bring some inconveniences. To run kotlin, it is mandatory for the kotlin library files to be available at runtime. While it is possible to provide these classes with the -classpath option, when starting the JVM, most spigot servers run in managed environments. The go-to workaround for this problem is to add these library files to the final jar by shading them. This will increase your jar size a lot.

KotlinLoader provides a custom PluginLoader, that will provide the Kotlin library classes for you.\

Included Kotlin Libraries

• kotlin-stdlib
• kotlin-stdlib-jdk8
• kotlin-stdlib-jdk7
• kotlinx-coroutines
• kotlin-reflect

Pros

• Write Idiomatic Kotlin!
• The main class can be an object singleton, instead of a normal class.
• Decrease size of the final plugin jar.

Cons

• This plugin uses a lot of reflection and injection hacks to allows Kotlin classes to be accessed by JavaPlugins
• Plugins extending KotlinPlugin should be located in the <server_root>/plugins/kotlin folder.

Roadmap

• Add support for .kts configuration
• Add support for annotation based plugin descriptions
• Add BungeeCord support

Usage

In the spigot server

Build or download the plugin and place it into your plugins folder like any other plugin. Note that plugins running with this pluginloader should go into the <server_root>/plugins/kotlin folder!

When writing a plugin

The KotlinLoader offers two ways to write a plugin.

A regelar KotlinPlugin should be written as any other Spigot Plugin. The main class should extend KotlinPlugin. It is possible to use object for the main class.

Events

The current Bukkit Event system does not fit within idiomatic Kotlin. The mandatory HandlerList forces you to write ugly companion objects which a @JvmStatic annotation. The KotlinLoader Plugin provides an event generation system which write this boilerplate for you!

Normal Events

Events using this generator feature should either extend dev.steyn.kotlinloader.api.event.Event as superclass or have the dev.steyn.kotlinloader.api.event.GenHandlers annotation. The latter one was introduced for applying the generator feature for Events which require a different superclass. Instantiation of the class dev.steyn.kotlinloader.api.event.Event is illegal outside of use of superclass. Please use the normal Bukkit event class.

Cancellable

The bukkit system for cancellable events also forces you to write alot of boilerplate. KotlinLoader introduces a default implementation which can be used through delegation.

class ServerFooEvent : Event() 

@GenHandlers
class PlayerFooEvent(who: Player) : PlayerEvent(who)

class CancellablePlayerFooEvent(who: Player) : PlayerEvent(who), Cancellable by Cancellable.default()

Compiling

KotlinLoader is a maven project. Use mvn package to build to project.

Dependency Information

Maven

<repository>
    <id>jitpack.io</id>
    <url>https://jitpack.io</url>
</repository>

<dependency>
    <groupId>com.github.steenooo</groupId>
    <artifactId>kotlin-loader</artifactId>
    <version>1.2.2</version>
    <scope>provided</scope>
</dependency>

Gradle

allprojects {
		repositories {
			...
			maven { url 'https://jitpack.io' }
		}
	}
  
dependencies {
	        implementation 'com.github.steenooo:kotlin-loader:1.2.2'
	}

This project was inspired by ScalaLoader