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Your First Feature

This guide builds one feature end-to-end: definition, targeting rules, and evaluation.

1) Define a namespace and a feature​

import io.amichne.konditional.context.*

object AppFeatures : Namespace("app") {
    val darkMode by boolean<Context>(default = false) {
        rule(true) { platforms(Platform.IOS) }
        rule(true) { locales(AppLocale.UNITED_STATES) }
    }
}

2) Create a context and evaluate​

val ctx = Context(
    locale = AppLocale.UNITED_STATES,
    platform = Platform.IOS,
    appVersion = Version.of(2, 0, 0),
    stableId = StableId.of("user-123"),
)

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

If no rule matches, the default value is returned.

What just happened​

  • A Namespace is a registry of features.
  • A Feature is a typed value with rules.
  • A Rule is criteria -> value mapping.
  • A Context provides runtime inputs used by rules.

Guarantees​

  • Guarantee: Evaluation always returns a non-null value of the declared type.

  • Mechanism: Features require a default value and return it when no rule matches.

  • Boundary: Konditional does not validate business logic; it only evaluates rules.

Next steps​