Why doesn't Scala Source close the underlying InputStream?
file-io, scala
Solution
`Scala.io._` is a barebones hack created for the sole purpose of supporting the XML library and the compiler. It is badly designed and suffers from many problems. Scala 2.8 will purport an improved version of it, though hardly anything to write home about.
There is an on-going third party effort by interested parties to develop a sound Scala I/O library. It aims to take home the lessons learned by the JDK7 I/O redesign, while providing an Scala-ish API.
Meanwhile... use Java libraries whenever your application stumbles upon the design problems of the present library.
Problem
I'm using Scala `Source.fromFile` however I can't seem to find a nice way of getting it to `close` the underlying `InputStream` once the file has been read. Here's my code that will fail with an `AssertionError` because the file cannot be deleted. ``` def main(args : Array[String]) : Unit = { val myFile = new File("c:/tmp/doodah.txt") var src = Source.fromFile(myFile) src.getLines.foreach(l => print(l)) val deleted: Boolean = myFile.delete assert (deleted , "File was not deleted - maybe the stream hasn't been closed in Source") } ``` Source has a method called `reset` however all that this does is recreate the source from the file. Internally `Source` creates an underlying `BufferedSource` that has a `close` method. However this is not exposed from Source. I'd hope that Source would release the file handle once the contents of the file had been read but it doesn't seem to do that. The best workaround I've seen so far is to essentially cast the `Source` to a `BufferedSource` and call `close`. ``` try { src.getLines.foreach(l => print(l)) } finally src match { case b: scala.io.BufferedSource => b.close } ``` Alternatively I could create a `Source` from an `InputStream` and manage the closing myself. However this seems somewhat dirty. How are you supposed to release the file handle when using `Source`?