Simple-Moduleloader

Simple Moduleloader is a Module Loading System very heavily inspired by QuickStartModuleLoader
but with the focus on simplicity in the Implementation but with few compromises.

I've tried to make getting started with this System very easy, but it should also be very extensible for those that need the customization

Before you begin!

Please note that I (like most of my projects) have written this library in Kotlin.

While i can imagine that using Kotlin is quite unpopular simply due to the additional size it brings with it.I don't have any plans to port this to pure java.
If you want to use a pure java version which is very small, use the original module-loader by the Nucleus team.

Getting Started

Dependencies

To include Simple-Moduleloader into your Project add the Bintray Repository & the Dependency.

repositories {
    maven("https://dl.bintray.com/nanabell/Sponge-Minecraft")
}

dependencies {
    implementation("com.nanabell.quickstart", "simple-moduleloader", "VERSION")
}

simple-moduleloader has the required kotlin libraries (v1.3.61) as well as configurate-core (3.6.1) declared as runtime dependency, If you use e.g shadow these will automatically be added to the shaded jar.

How to get started

To get started with Modules you need some module classes. A Module requires a few things:

• Module Config Class that implements com.nanabell.quickstart.config.ModuleConfig
• Implement com.nanabell.quickstart.Module<ModuleConfig>
• Have @com.nanabell.quickstart.RegisterModule Annotation

Currently, every Module must have a Config Class which will be (De)-Serialized. with the configurate library.

Instead of implementing the Module Interface directly you can use the AbstractModule<ModuleConfig> abstract class.
This class handles bridging the Module Class with the ConfigAdapter.

Let's start by creating the ModuleConfig Class:

import com.nanabell.quickstart.config.ModuleConfig
import ninja.leaping.configurate.objectmapping.Setting
import ninja.leaping.configurate.objectmapping.serialize.ConfigSerializable

@ConfigSerializable
data class DemoConfig(

    @Setting("my-value", comment = "This is a Demo Config entry")
    val mySerializedProperty: String = "Default Value"

) : ModuleConfig

As you can see apart from the ModuleConfig annotation this is a default Configurate POJO Class

Next up is the actual Module Class.

This Class is the main entry point for the Module.

import com.nanabell.quickstart.AbstractModule

@RegisterModule(id = "unique-id", name = "Display Name", description = "Free Description", softDependencies = ["soft-dep1", "soft-dep2"], dependencies = ["requried-dep"], required = false /*if true cant be disabled*/)
class DemoModule : AbstractModule<DemoConfig>() {

    override fun preEnable() {
        TODO("Not yet implemented")
    }

    override fun onEnable() {
        TODO("Not yet implemented")
    }

    override fun postEnable() {
        TODO("Not yet implemented")
    }

}

Here we use the AbstractModule so we don't have to implement methods like getConfig() or getConfigAdapter()

Every Module has to implement the 3 main Methods and has 2 optional ones.

• getConfigConstructor() - Optional Allows to override the default no-arg ConfigConstructor used to create a instance of the ModuleConfig.
• preEnable() - Called just after the Config files have been attached to the module. Use this phase to Construct any Essential components, like Services etc.
• checkExternalDependencies() - Optional. Use this to connect to any external resources. Throwing a MissingDependencyException will indicate that the Module cannot load due to missing external dependencies.
• onEnable() - The Main Phase for every Module. Construct any runtime components here.
• postEnable() - Cleanup phase, use this to remove any resources only needed to construct the module.

That's everything for the Module.

The actual Module Loader

Just defining Modules won't do much as we still need a Instance of the Actual ModuleLoader.
While this could be done at any time i suggest to use the GamePreInitializationEvent & GameInitializationEvent respectively.

GamePreInitializationEvent: Creating Container and discovering Modules

Create a new Event Listener for the GamePreInitializationEvent to construct the ModuleContainer

@Listener
fun preInit(event: GamePreInitializationEvent) {
    try {
        val moduleConfig = HoconConfigurationLoader.builder()
                .setPath(configDir.resolve("my-config-filename.conf"))
                .build()

        moduleContainer = DiscoveryModuleContainer.builder()
                .setConfigurationLoader(moduleConfig)
                .setModuleConfigKey("-modules")
                .setPackageToScan(javaClass.`package`.name + ".module")
                .setLogger(logger)
                .build(true)
    } catch (e: ModuleDiscoveryException) {
        logger.error("Plugin PreInitialization failed!", e)
    }
}

Here I use the HoconConfigurationLoader with the default options and use the file my-config-filename.conf

• setConfigurationLoader() - Required Sets the ConfigurationLoader used to load & save the Configs.
• setModuleConfigKey() - Required Name of the Node where the ENABLE/DISABLE configs will be
• setPackageToScan() - Required Name of the root package to scan from. In my case this is the Package where the Plugin is located + .module e.g = com.myplugin.module.**
• setLogger() - Optional define a customer logger else it will create one with LoggerFactory.getLogger(this::class.java)
• build() - Actually Build the ModuleContainer, optionally pass true to instantly start discovering Modules else call moduleContainer.startDiscover()

There are more options, but those are for more specific requirement i won't go into here.
Note: The ModuleContainer will error if it can't find any Modules in the Discovering Phase and will be unusable after that

GameInitializationEvent: Loading the Modules

Last step to success is actually loading the modules that have been discovered.

@Listener
fun onInit(event: GameInitializationEvent) {
    try {
        moduleContainer.loadModules(true)
    } catch (e: ModuleException) {
        logger.error("Plugin Initialization failed!", e)
    }
}

This will actually load the Modules and construct them. The Boolean argument indicates if the ModuleLoader should cancel as soon as one Module throws an Error.
If set to false it will continue with the rest of the modules which do not depend on the crashed Module.
Note: The ModuleContainer will error if all Modules are disabled for one or the other reason and there are actually no Modules left to construct.

Loading Order

If a Module errors or is marked Disabled it will stop loading:

• Construct Modules
• Load ModulesStatusConfigs
• PreEnable phase
• checkExternalDependencies
• OnEnable phase
• PostEnable phase
• CreateDefaultConfigs

Credits

This whole Project has been very heavily based upon QuickStartModuleLoader by the NucleusPowered team