Auto close/dispose resource / published by https://github.com/dacr/code-examples-manager #671d5671-7524-476e-9b66-744ca9bbaf6f/2b3a1e6e54eabde44ce2ce1883bc72ed737fa496

scala-autoclose.sc

// summary : Auto close/dispose resource
// keywords : scala, autoclose, autodispose, @testable
// publish : gist
// authors : David Crosson
// license : Apache NON-AI License Version 2.0 (https://raw.githubusercontent.com/non-ai-licenses/non-ai-licenses/main/NON-AI-APACHE2)
// id : 671d5671-7524-476e-9b66-744ca9bbaf6f
// created-on : 2020-05-31T19:54:52Z
// managed-by : https://github.com/dacr/code-examples-manager
// run-with : scala-cli $file

// ---------------------
//> using scala "3.4.2"
// ---------------------

// ----------------------------------
// -- The legacy way

class That() {
  def sayHello():Unit = {
    println("Hello")
  }
  def close():Unit = {
    println("Closed")
  }
}

import reflect.Selectable.reflectiveSelectable

def using[R, T <: { def close():Unit }](getres: => T)(doit: T => R): R = {
  val res = getres
  try doit(res) finally res.close()
}

using(new That()) {that => 
  that.sayHello()
}


// ----------------------------------
// -- The scala 2.13 way

import scala.util.Using

class ThatAgain() extends AutoCloseable {
  def sayHello():Unit = {
    println("Hello")
  }
  override def close():Unit = {
    println("Closed")
  }
}

Using(new ThatAgain()) { that =>
  that.sayHello()
}