trywithmanyresources.kt

import java.io.Closeable
import java.util.*

class ResourceContext {
    private val toClose = mutableListOf<Closeable>()
    fun <A : Closeable> open(thing: A): A {
        toClose.add(thing)
        return thing
    }

    fun onExit() {
        throw toClose.map {
            try {
                it.close()
                null
            } catch (e: Exception) {
                e
            }
        }.firstOrNull() ?: return
    }
}


inline fun <R> tryWithManyResourcesContext(block: ResourceContext.() -> R): R {
    val ctx = ResourceContext()
    try {
        return ctx.run(block)
    } finally {
        ctx.onExit()
    }
}


fun main() {
    val text = tryWithManyResourcesContext {
        val scanner = open(Scanner(System.`in`))
        return@tryWithManyResourcesContext scanner.nextLine()
    }
    println(text)
}