From Fzzy Config 0.5.9, there is a simple registration system built into the PlatformApi for cross-platform registration to built-in or modded Registry objects.

Registrar Pieces and Parts

The system is built out of two basic parts

Registrar

The registration manager object for a particular Registry. Game objects are registered into this, much like a DeferredRegister from a (Neo)Forge modding context.

RegistrySupplier

The output object of a Registrar, this supplier performs all the basic registry-reference actions you should need

RegistrySupplier provides:

• get() - The registered object; it is a Supplier<T> of the object type.
• getKey() - The RegistryKey the object is registered with.
• getId() - The Identifier the object is registered with.
• getEntry() - The RegistryEntry that stores the object in the registry.

Creating a Registrar

Create a new Registrar using the PlatformApi accessed through the ConfigApi.

val myItemRegistrar: Registrar<Item> = ConfigApi.platform().createRegistrar(MOD_ID, Registries.ITEM)

Using the Registrar

Once you have a registrar, there are two primary activities you need to do with it.

1. register() objects to it
2. init() the registrar to link it to the mod loading system

val myItemRegistrar: Registrar<Item> = ConfigApi.platform().createRegistrar(MOD_ID, Registries.ITEM)

val ITEM_1: RegistrySupplier<Item> = myItemRegistrar.register("item_1", Supplier { Item1() })

//mod initializer, in your mod entrypoint or related initializer
fun myCommonInit() {
    myItemRegistrar.init()
}

Load Order

Fzzy Config doesn't currently have the ability to strictly work with load orders, so keep this in mind if you need to register in a certain order relative to another mod. On Fabric, load orders aren't even a concept.