Simple Scala pattern for “using/try-with-resources” (Automatic Resource Management)

Question

C# has using with the IDisposable interface. Java 7+ has identical functionality with try and the AutoCloseable interface

Answer 1

This is the code I use:

def use[A <: { def close(): Unit }, B](resource: A)(code: A ⇒ B): B =
    try
        code(resource)
    finally
        resource.close()

Unlike Java try-with-resources, the resource doesn't need to implement AutoCloseable. Only a close() method is needed. It only supports one resource.

Here is an example use with an InputStream:

val path = Paths get "/etc/myfile"
use(Files.newInputStream(path)) { inputStream ⇒
    val firstByte = inputStream.read()
    ....
}