edwardt / scala-arm

This project aims to be the Scala Incubator project for Automatic-Resource-Management in the scala library

Scala Automatic Resource Management

This project is an attempt to provide an Automatic-Resource-Management library for the scala distribution. It is based off of code contributed to the Scalax project.

Using scala-arm

In SBT:

libraryDependencies += "com.jsuereth" %% "scala-arm" % "1.3"

or

libraryDependencies += "com.jsuereth" % "scala-arm_2.9.2" % "1.3"
libraryDependencies += "com.jsuereth" % "scala-arm_2.10" % "1.3"

In Maven:

<dependency>
   <groupId>com.jsuereth</groupId>
   <artifactId>scala-arm_${scala.binary.version}</artifactId>
   <version>1.3</version>
</dependency>

Examples

Scala-arm provides many ways of managing resources and re-using code. Here's a few examples.

Imperative Style

import resource._
// Copy input into output.
for(input <- managed(new java.io.FileInputStream("test.txt"));
    output <- managed(new java.io.FileOutputStream("test2.txt"))) {
  val buffer = new Array[Byte](512)
  def read(): Unit = input.read(buffer) match {
    case -1 => ()
    case  n => output.write(buffer,0,size); read()
  }
  read()
}

Delimited continuation style

import resource._
import java.io.{File, FileInputStream => Fin, FileOutputStream => Fout}
def copyFile(from: File, to: File): Unit =
  withResources {
    val f = managed(new Fin(from)).reflect[Unit]
    val t = managed(new Fout(to)).reflect[Unit]
    val buffer = new Array[Byte](512)
    def read(): Unit = f.read(buffer) match {
      case -1 => ()
      case  n => t.write(buffer,0,n); read()
    }
    read()
}

For more information on usage, see Usage

SCALA LICENSE

Copyright (c) 2002-2013 EPFL, Lausanne, unless otherwise specified. All rights reserved.

This software was developed by the Programming Methods Laboratory of the Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland.

Permission to use, copy, modify, and distribute this software in source or binary form for any purpose with or without fee is hereby granted, provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

3. Neither the name of the EPFL nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.