Overview

NeoForge supports full client + server environments, the Cloth Config GUI, and resource pack / data pack generation; bytecode transformation is implemented via the coremod mechanism.

Entrypoints and Load Timing

• Entrypoint class: net.luojiayuan.jython.mod.JythonModNeoForge (@Mod("jythonmod"))
• Registration timing difference: NeoForge freezes the registry during mod construction, so Python mods cannot register items/blocks in the constructor. Therefore main (common environment) is deferred to the RegisterEvent phase (when the registry is writable), while client / server environments run in FMLClientSetupEvent / FMLDedicatedServerSetupEvent respectively (determined by FMLEnvironment.getDist()).
• Each environment runs only once (guarded by AtomicBoolean).

Class Names and Mapping

NeoForge uses official (Mojang) mappings; class names match the Yarn names in 1.21.11 and can be used directly, with no intermediary conversion needed.

Configuration

• Cloth Config, config file config/jython-mod.json, supports an in-game GUI.
• Dependency declaration: META-INF/neoforge.mods.toml requires cloth_config >= 21.11.152.

Bytecode Transformation

Supported, via the coremod mechanism: NeoForgeBytecodeProcessor implements the ClassProcessor SPI (META-INF/services/net.neoforged.neoforgespi.transformation.ClassProcessor) and processes class bytecode after Mixin and COMPUTING_FRAMES. The Python side still uses BytecodeHelper.registerTransformer() (see libs.md).

Resource Packs / Data Packs

Supported. Same as Fabric (see resources.md).

Build and Deployment

./gradlew neoforgeJar

Artifact: build/libs/jython-mod-<version>-neoforge.jar (bundles the GraalPy runtime and the coremod service file).

Deployment: put the JAR in the mods/ folder, put the Python module ZIP in the jymods/ folder, then start the game.

Dependencies: NeoForge >= 21.11, Minecraft [1.21.11, 1.22), Cloth Config. See neoforge.mods.toml.

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Contributors: RyanLuoJiayuan1120

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