Scala-IO Core: To Resource Converters

In order to simplify integration with existing libraries, most commonly Java libraries, Scala-IO provides a JavaConverters object with implicit methods that add as*** methods (asInput, asOutput, asSeekable, etc...) to several types of objects.  It is the same pattern as in the scala.collection.JavaConverters object.

These methods can be used instead of the Resource.from*** methods to provide a slightly nicer appearing code.

There is one warning. When using JavaConverters, instead of Resource.from*** for creating Input/Output/Seekable/etc... objects, the chances of falling into the trap of creating non-reusable resources or causing a resource leak is increased. See: scala-io-core-reusable-resources for more details on this.

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// JavaConverters object contains the implicit methods // which add the as*** methods to the applicable _normal_ objects import scalax.io.JavaConverters._   // Several objects can be converted to input objects using // asInput.  URLs, File, RandomAccessFile, InputStream, Traversable[Byte] // Array[Byte], ReadableByteChannel val input = new URL("http://www.camptocamp.com").asInput   // simple demonstation using the newly created input object println(input.bytes.size)   // asSeekable can only be applied to a few objects at the // moment.  Including RandomAccessFile, SeekableByteChannel, // File and perhaps in future mutable Sequences val file = new java.io.File("somefile.txt").asSeekable   // demonstrate a seekable method.  This method // ensures the file is empty file.truncate(0)   // write hi using the Output  API file.write("hi :)")   // output the file to the console to see the results println(file.string)   // asUnmanaged*** created Unmanaged resources for // operations.  The Unmanaged Resource post will // discuss this in more detail but essentially the // resource is not closed and thus is useful when // dealing with underlying objects that should not // be closed like System.out val unmanagedOutput = System.out.asUnmanagedOutput   // prints to standard out: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 unmanagedOutput.writeStrings(1 to 10 map (_.toString), ", ")   // prints: Hello World // This demonstrates how a simple Array or Traversable can be easily used // as an Input object.  The array is Hello world encoded as normal latin1 println(Array(72, 101, 108, 108, 111, 32, 87, 111, 114, 108, 100).asInput.string)   // prints: Hll Wrld // Raw Strings and Reader objects cannot currently be converted to an Input object // but can be converted to ReadChars object (Essentially the character API of Input) println("Hello World".asReadChars.chars.filterNot(c => "aeiou" contains c) mkString)   // Similarly Writer objects cannot be Output objects since they can't write // bytes so asWriteChars is used to be able to have the string writing // capabilities of Scala-IO new java.io.FileWriter("somefile.txt").asWriteChars write "Hi"   // prints: Hi println(new java.io.FileReader("somefile.txt").asReadChars.string)