Rules

RulesEvaluator

The IRulesEvaluator interface evaluates the given rules to determine whether a file or parameter should be used. Some parameters or files are only applicable in specific OS versions or when certain features are enabled.

Examples

• OS-specific files: lwjgl-windowsd is only enabled on Windows.

• Feature-specific parameters: The --demo parameter is only used if the is_demo_user feature is enabled.

Game versions provide a rules property to specify in which environments particular features should be enabled.

Built-in Implementation

The built-in implementation of IRulesEvaluator, named RulesEvaluator, behaves identically to the Mojang Launcher’s implementation. In most cases, this implementation is sufficient.

If you need custom behavior, you can implement your own IRulesEvaluator. You can set your IRulesEvaluator in MinecraftLauncherParameters.

RulesEvaluatorContext

RulesEvaluatorContext represents the current environment information for evaluating the given rules. This includes the OS type, version, architecture, and list of enabled features currently running.

The code below creates a RulesEvaluatorContext that represents the current environment.

var context = new RulesEvaluatorContext(LauncherOSRule.Current, []);

If you want to simulate running in a different environment, you can initialize the RulesEvaluatorContext by yourself.

var context = new RulesEvaluatorContext(new LauncherOSRule("windows", "64", "10.0"), []);

You can set the value of RulesContext for the launcher.

var launcher = new MinecraftLauncher();
launcher.RulesContext = new RulesEvaluatorContext(new LauncherOSRule("windows", "64", "10.0"), []);