Lantern Load

Lantern Load provides a simple implementation of version resolution intended to allow data packs and their dependencies to load in a controllable order. Projects that depend on this library include AESTD, Gamemode 4, and PlayerDB.

This project is released under the BSD 0-Clause License, which in short means you can do whatever you want with these files, with nothing expected in return. You do not even have to credit us.

Warning

This pack is for Minecraft 1.17 or higher. This version of Lantern Load will not work correctly in 1.16 and will not even load in versions prior to 1.16. If you must release a pack for 1.16, please use an older version of Lantern Load.

Usage

Copy the load and minecraft directories from load/data/ into your pack’s data folder. The copied in load.json should now call #load:_private/load.
Add load functions in the desired load order to data/load/tags/functions/load.json or the other tags pre_load.json and post_load.json. For most cases you should prefer load.json.

Example load.json contents:

{
    "values": [
        "pack1:load",
        "your_pack:load"
    ]
}

Pack Versioning Specification

The recommended (but not mandatory) use of the load.status scoreboard:

Each pack should define at least one fake player whose name includes the name of the pack. At least one of these fake players should have a value that should not be decreased in future updates to the pack. This score value may be defined to remain constant, or increment in future updates to the pack with or without a semantic meaning.

This specification is intentionally open-ended as it is not this project’s goal to force a specific versioning scheme on every data pack. Following the specification simply implies that one can detect when your pack is loaded by checking your load.status score.

Avoiding the `#minecraft:tick` tag

The #minecraft:tick tag has several problems, the worst of which is that it runs before #minecraft:load, meaning that your pack may be ticked without first being initialized. Lantern Load is meant to allow every pack to initialize itself in a predictable order within the same tick, including on reload, and #minecraft:tick interferes with this design goal. The recommended solution is to instead invoke schedule from a function defined in #load:load.

Example contents of load and tick functions:

# your_pack:load
scoreboard players set your_pack load.status 1
schedule function your_pack:tick 1t

# your_pack:tick
say this is a tick!
schedule function your_pack:tick 1t

Checking for dependencies

In your load function, you may wish to check the value of another pack’s score in load.status before initializing scoreboards or scheduling your tick function. Doing so is a useful way to handle missing dependencies and reduce the risk of your data pack causing errors.

Example of checking the value of another pack’s load status:

# your_pack:load
schedule clear your_pack:tick
execute if score other_pack load.status matches 1 run scoreboard players set your_pack load.status 1
execute if score your_pack load.status matches 1 run function your_pack:init

# your_pack:init
scoreboard objectives add your_objective dummy
schedule function your_pack:tick 1t

# your_pack:tick
scoreboard players add your_score your_objective 1
schedule function your_pack:tick 1t

License

Lantern Load is made freely available under the terms of the BSD 0-Clause License. Third-party contributions shall be licensed under the same terms unless explicitly stated otherwise.