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Core API Reference

Reference for evaluating features in a total, deterministic runtime path.

Feature.evaluate(context, registry): T​

Standard evaluation API.

fun <T : Any, C : Context, M : Namespace> Feature<T, C, M>.evaluate(
    context: C,
    registry: NamespaceRegistry = namespace,
): T

  • Guarantee: Returns a value of type T and never returns null for supported runtime usage.

  • Mechanism: Evaluation returns the first matching rule value or the declared default.

  • Boundary: Throws IllegalStateException if the feature is not registered in the registry.

Example​

val enabled: Boolean = AppFeatures.darkMode.evaluate(context)

Behavior​

  1. Resolve the feature definition from the registry.
  2. If the registry kill-switch is enabled, return the default.
  3. If the flag is inactive, return the default.
  4. Evaluate rules by descending specificity.
  5. Apply ramp-up to the first matching rule.
  6. Return the rule value or the default.

Observability and explain diagnostics​

  • Public explain APIs were removed.
  • Internal diagnostics are still produced for sibling modules (OpenFeature, observability, telemetry) via internal API opt-in.
  • Application code should use evaluate(...) as the public entrypoint.

Next steps​