Support for inheritance in Command and Notification Handling

[osoykan]

Description

Currently, kediatR does not support inherited command and notification handling. But, inheritance is sometimes needed to unify repetitive handler logic into the base class.

class MyCommandForInheritance : Command

abstract class MyAsyncCommandHandlerFor<TCommand : Command> : AsyncCommandHandler<TCommand>

class MyInheritedAsyncCommandHandler : MyAsyncCommandHandlerFor<MyCommandForInheritance>() {
    override suspend fun handleAsync(command: MyCommandForInheritance) {
        // should be invoked but was not registered at all
    }
}

As this example shows, MyInheritedAsyncCommandHandleris not accessible and not registered to the Registry because asyncCommandMap does not consider superClasses while building the container.

Implementation

In the RegistryImpl.kt the collection is being iterated over only the interfaces.

kediatR/kediatr-core/src/main/kotlin/com/trendyol/kediatr/RegistryImpl.kt

Lines 68 to 71 in 698b6ce

	(it.genericInterfaces).forEach { genericInterface ->
	if ((genericInterface is ParameterizedType) && genericInterface.rawType as Class<*> == AsyncCommandHandler::class.java) {
	val commandClazz = extractCommandClass<Command>(genericInterface)
	asyncCommandMap[commandClazz] = AsyncCommandProvider(dependencyProvider, it)

The fix should be located here.

Also, consider:

• Lift the common registry logic with PartialFunction

[osoykan]

closed with #27