TempPath (<: AutoCloseable) and withTempFile|Dir convenience methods

Readme.adoc

@@ -1157,6 +1157,43 @@ os.followLink(wd / "misc" / "folder-symlink") ==> Some(wd / "folder1")
 os.followLink(wd / "misc" / "broken-symlink") ==> None
 ----
 
+==== `os.temp.withFile`
+
+[source,scala]
+----
+os.temp.withFile[A](fun: Path => A): A
+----
+
+Creates a temporary file, passes it to the given function and removes it immediately after the function completed, even if the function threw an exception. 
+
+This doesn't rely on the JVM's `deleteOnExit` handler, therefor the temp file gets deleted even if JVM never stopps gracefully (e.g. because it's intended to run continually, or the process get's killed from the outside).
+
+[source,scala]
+----
+os.temp.withFile { file =>
+  os.write(file, "some content")
+}
+----
+
+==== `os.temp.withDir`
+
+[source,scala]
+----
+os.temp.withDir[A](fun: Path => A): A
+----
+
+Creates a temporary directory, passes it to the given function and removes it immediately after the function completed, even if the function threw an exception. 
+
+This doesn't rely on the JVM's `deleteOnExit` handler, therefor the temp dir gets deleted even if JVM never stopps gracefully (e.g. because it's intended to run continually, or the process get's killed from the outside).
+
+[source,scala]
+----
+os.temp.withDir { file =>
+  val file = dir / "somefile"
+  os.write(file, "some content")
+}
+----
+
 ==== `os.temp`
 
 [source,scala]

build.sc

@@ -35,6 +35,7 @@ object Deps {
   val acyclic = ivy"com.lihaoyi:::acyclic:0.3.6"
   val jna = ivy"net.java.dev.jna:jna:5.13.0"
   val geny = ivy"com.lihaoyi::geny::1.0.0"
+  val scalaCollectionCompat = ivy"org.scala-lang.modules::scala-collection-compat::2.9.0"
   val sourcecode = ivy"com.lihaoyi::sourcecode::0.3.0"
   val utest = ivy"com.lihaoyi::utest::0.8.1"
   def scalaLibrary(version: String) = ivy"org.scala-lang:scala-library:${version}"
@@ -143,10 +144,15 @@ trait OsLibModule extends CrossScalaModule with PublishModule with AcyclicModule
   )
   def platformSegment: String
   override def millSourcePath = super.millSourcePath / oslib.up
-  override def sources = T.sources(
-    millSourcePath / "src",
-    millSourcePath / s"src-$platformSegment"
-  )
+  override def sources = T.sources {
+    Seq(
+      PathRef(millSourcePath / "src"),
+      PathRef(millSourcePath / s"src-$platformSegment")
+    ) ++
+      ZincWorkerUtil.versionRanges(crossScalaVersion, scalaVersions).map(vr =>
+      PathRef(millSourcePath / s"src-${vr}"))
+
+  }
 }
 
 trait OsLibTestModule extends ScalaModule with TestModule.Utest with SafeDeps {
@@ -168,9 +174,13 @@ trait OsLibTestModule extends ScalaModule with TestModule.Utest with SafeDeps {
 
 trait OsModule extends OsLibModule {
   override def artifactName = "os-lib"
-  override def ivyDeps = Agg(
-    Deps.geny
-  )
+  override def ivyDeps = T {
+    val scalaV = scalaVersion()
+    if (scalaV.startsWith("2.11") || scalaV.startsWith("2.12")) {
+      // include collection compat, mostly for a backported scala.util.Using
+      Agg(Deps.geny, Deps.scalaCollectionCompat)
+    } else Agg(Deps.geny)
+  }
 }
 
 trait WatchModule extends OsLibModule {

os/src/Path.scala

@@ -1,7 +1,8 @@
 package os
 
 import java.net.URI
-import java.nio.file.Paths
+import java.nio.file.{LinkOption, Paths}
+import java.nio.file.Files
 
 import collection.JavaConverters._
 import scala.language.implicitConversions
@@ -450,7 +451,7 @@ trait ReadablePath {
 class Path private[os] (val wrapped: java.nio.file.Path)
     extends FilePath with ReadablePath with BasePathImpl {
   def toSource: SeekableSource =
-    new SeekableSource.ChannelSource(java.nio.file.Files.newByteChannel(wrapped))
+    new SeekableSource.ChannelSource(Files.newByteChannel(wrapped))
 
   require(wrapped.isAbsolute, s"$wrapped is not an absolute path")
   def segments: Iterator[String] = wrapped.iterator().asScala.map(_.toString)
@@ -497,7 +498,32 @@ class Path private[os] (val wrapped: java.nio.file.Path)
 
   def resolveFrom(base: os.Path) = this
 
-  def getInputStream = java.nio.file.Files.newInputStream(wrapped)
+  def getInputStream = Files.newInputStream(wrapped)
+}
+
+class TempPath private[os] (wrapped: java.nio.file.Path)
+  extends Path(wrapped) with AutoCloseable {
+
+  override def close(): Unit = deleteRecursively(wrapped)
+
+  /** Wouldn't it be nice if we could just call `os.remove.all(this)`?
+    * For some reason, Scala 2 throws a rather obscure `[error] Unwanted cyclic dependency`
+    */
+  private def deleteRecursively(ioPath: java.nio.file.Path): Unit = {
+    if (Files.isDirectory(ioPath)) {
+      // while we support Scala 2.11 we need (something like) this:
+      Files.list(ioPath).forEach(
+        new java.util.function.Consumer[java.nio.file.Path] {
+          override def accept(path: java.nio.file.Path): Unit =
+            deleteRecursively(path)
+        }
+      )
+
+      // this works for Scala 2.12+
+      // Files.list(ioPath).forEach(deleteRecursively)
+    }
+    Files.deleteIfExists(ioPath)
+  }
 }
 
 sealed trait PathConvertible[T] {

os/src/TempOps.scala

@@ -1,11 +1,23 @@
 package os
 
-import java.nio.file.attribute.{FileAttribute, PosixFilePermission, PosixFilePermissions}
+import java.nio.file.attribute.{FileAttribute, PosixFilePermissions}
+import scala.util.Using
 
 /**
- * Alias for `java.nio.file.Files.createTempFile` and
- * `java.io.File.deleteOnExit`. Pass in `deleteOnExit = false` if you want
- * the temp file to stick around.
+ * Create temporary files and directories. [[withFile]] and [[withDir]] 
+ * are convenience methods that handle the most common case. They delete the temp
+ * file/dir immediately after the given function completed - even if the given
+ * function threw an exception. 
+ * 
+ * {{{
+ * os.temp.withFile { file =>
+ *   os.write(file, "some content")
+ * }
+ * }}} 
+ * 
+ * [[os.temp()]] and [[os.temp.dir()]] are aliases for
+ * `java.nio.file.Files.createTemp[File|Directory]` and `java.io.File.deleteOnExit`.
+ * Pass in `deleteOnExit = false` if you want the temp file to stick around.
  */
 object temp {
 
@@ -27,7 +39,7 @@ object temp {
       suffix: String = null,
       deleteOnExit: Boolean = true,
       perms: PermSet = null
-  ): Path = {
+  ): TempPath = {
     import collection.JavaConverters._
     val permArray: Array[FileAttribute[_]] =
       if (perms == null) Array.empty
@@ -40,7 +52,7 @@ object temp {
 
     if (contents != null) write.over(Path(nioPath), contents)
     if (deleteOnExit) nioPath.toFile.deleteOnExit()
-    Path(nioPath)
+    new TempPath(nioPath)
   }
 
   /**
@@ -56,7 +68,7 @@ object temp {
       prefix: String = null,
       deleteOnExit: Boolean = true,
       perms: PermSet = null
-  ): Path = {
+  ): TempPath = {
     val permArray: Array[FileAttribute[_]] =
       if (perms == null) Array.empty
       else Array(PosixFilePermissions.asFileAttribute(perms.toSet()))
@@ -67,7 +79,59 @@ object temp {
     }
 
     if (deleteOnExit) nioPath.toFile.deleteOnExit()
-    Path(nioPath)
+    new TempPath(nioPath)
   }
 
+  /**
+    * Convenience method that creates a temporary file and automatically deletes it
+    * after the given function completed - even if the function throws an exception. 
+    * 
+    * {{{
+    * os.temp.withFile { file =>
+    *   os.write(file, "some content")
+    * }
+    * }}} 
+    */
+  def withFile[A](
+    fun: Path => A,
+    contents: Source = null,
+    dir: Path = null,
+    prefix: String = null,
+    suffix: String = null,
+    perms: PermSet = null
+  ): A = {
+    Using.resource(os.temp(
+      contents = contents,
+      dir = dir,
+      prefix = prefix,
+      suffix = suffix,
+      deleteOnExit = false, // TempFile.close() deletes it, no need to register with JVM
+      perms = perms
+    ))(fun)
+  }
+
+  /**
+    * Convenience method that creates a temporary directory and automatically deletes it
+    * after the given function completed - even if the function throws an exception. 
+    * 
+    * {{{
+    * os.temp.withDir { file =>
+    *   val file = dir / "somefile"
+    *   os.write(file, "some content")
+    * }
+    * }}} 
+    */
+  def withDir[A](
+    fun: Path => A,
+    dir: Path = null,
+    prefix: String = null,
+    perms: PermSet = null
+  ): A =
+    Using.resource(os.temp.dir(
+      dir = dir,
+      prefix = prefix,
+      deleteOnExit = false, // TempFile.close() deletes it, no need to register with JVM
+      perms = perms
+    ))(fun)
+
 }

os/test/src/TempPathTests.scala

@@ -0,0 +1,77 @@
+package test.os
+
+import os._
+import scala.util.Using
+import utest.{assert => _, _}
+
+object TempPathTests extends TestSuite{
+  val tests = Tests {
+
+    test("convenience methods") {
+      test("temp.withFile") {
+        var tempFilePath: String = null
+        os.temp.withFile { file =>
+          tempFilePath = file.toString
+          assert(os.exists(file))
+        }
+        assert(!os.exists(os.Path(tempFilePath)),
+          s"temp file did not get auto-deleted after `Using` block: $tempFilePath")
+      }
+      test("temp.withDir") {
+        var tempDirPath: String = null
+        var tempFilePath: String = null
+        os.temp.withDir { dir =>
+          val file = dir / "somefile"
+          tempDirPath = dir.toString
+          tempFilePath = file.toString
+          os.write(file, "some content")
+          assert(os.exists(dir))
+          assert(os.exists(file))
+        }
+        assert(!os.exists(os.Path(tempDirPath)),
+          s"temp dir did not get auto-deleted after `Using` block: $tempDirPath")
+      }
+    }
+
+    test("delete after `Using` block") {
+      test("single file") {
+        var tempFilePath: String = null
+        Using(os.temp()) { file =>
+          tempFilePath = file.toString
+          assert(os.exists(file))
+        }
+        assert(!os.exists(os.Path(tempFilePath)),
+          s"temp file did not get auto-deleted after `Using` block: $tempFilePath")
+      }
+      test("directory") {
+        var tempDirPath: String = null
+        var tempFilePath: String = null
+        Using(os.temp.dir()) { dir =>
+          val file = dir / "somefile"
+          tempDirPath = dir.toString
+          tempFilePath = file.toString
+          os.write(file, "some content")
+          assert(os.exists(dir))
+          assert(os.exists(file))
+        }
+        assert(!os.exists(os.Path(tempDirPath)),
+          s"temp dir did not get auto-deleted after `Using` block: $tempDirPath")
+      }
+
+      test("multiple files") {
+        var tempFilePaths: Seq[String] = Nil
+        Using.Manager { use =>
+          val file1 = use(os.temp())
+          val file2 = use(os.temp())
+          val files = Seq(file1, file2)
+          tempFilePaths = files.map(_.toString)
+          files.foreach(file => assert(os.exists(file)))
+        }
+        tempFilePaths.foreach { file =>
+          assert(!os.exists(os.Path(file)),
+            s"temp file did not get auto-deleted after `Using` block: $file")
+        }
+      }
+    }
+  }
+}