Question

In the code below, if I uncomment the for loop the file no longer gets deleted

val file = "myfile.csv"
//for (line <- Source.fromFile(file).getLines()) { }
new File(file).delete()

If so is there some type of close function that I should be calling?

Answer 1

There is some sort of close that you should be calling:

val file = "myfile.csv"
val source = Source.fromFile(file)
for (line <- source.getLines()) { }
source.close
new File(file).delete

but this is a bit tedious. If you rewrite the for loop as

source.getLines().foreach{ line => }

you can then

class CloseAfter[A <: { def close(): Unit }](a: A) {
  def closed[B](f: A => B) = try { f(a) } finally { a.close }
}
implicit def close_things[A <: { def close(): Unit }](a: A) = new CloseAfter(a)

and now your code would become

val file = "myfile.csv"
Source.fromFile(file).closed(_.foreach{ line => })
new File(file).delete

(which would be a benefit if you’re doing it many times in your code, or if you already maintain your own library of helpful functions and it would be easy to add the closing implicit just once there so you could use it everywhere).