object Declaration — Singleton

object Database {
    private val cache = mutableMapOf<String, String>()

    fun put(k: String, v: String) { cache[k] = v }
    fun get(k: String): String? = cache[k]
    fun size() = cache.size
}

fun main() {
    Database.put("api_url", "https://api.example.com")
    println(Database.get("api_url"))            // https://api.example.com
    println(Database.size())                     // 1

    // Anonymous object — one-shot instance with interface override
    val handler = object : Runnable {
        override fun run() {
            println("running…")
        }
    }
    handler.run()

    // Anonymous object that captures from the enclosing scope
    var counter = 0
    val ticker = object {
        fun tick() { counter++; println("tick $counter") }
    }
    ticker.tick(); ticker.tick()
}