add extraLoggers to make it easier to add loggers

main/Defaults.scala

@@ -62,6 +62,7 @@ object Defaults extends BuildCommon
 		credentials :== Nil,
 		scalaHome :== None,
 		javaHome :== None,
+		extraLoggers :== { _ => Nil },
 		version :== "0.1",
 		outputStrategy :== None,
 		exportJars :== false,
@@ -90,6 +91,7 @@ object Defaults extends BuildCommon
 	))
 	def projectCore: Seq[Setting[_]] = Seq(
 		name <<= thisProject(_.id),
+		logManager <<= extraLoggers(LogManager.defaults),
 		runnerSetting
 	)
 	def paths = Seq(

main/Keys.scala

@@ -26,6 +26,7 @@ object Keys
 	val showSuccess = SettingKey[Boolean]("show-success", "If true, displays a success message after running a command successfully.")
 	val showTiming = SettingKey[Boolean]("show-timing", "If true, the command success message includes the completion time.")
 	val timingFormat = SettingKey[java.text.DateFormat]("timing-format", "The format used for displaying the completion time.")
+	val extraLoggers = SettingKey[ScopedKey[_] => Seq[AbstractLogger]]("extra-loggers", "A function that provides additional loggers for a given setting.")
 	val logManager = SettingKey[LogManager]("log-manager", "The log manager, which creates Loggers for different contexts.")
 	val logBuffered = SettingKey[Boolean]("log-buffered", "True if logging should be buffered until work completes.")
 

main/LogManager.scala

@@ -17,6 +17,7 @@ object LogManager
 		manager(data, task, to)
 	}
 	lazy val default: LogManager = withLoggers()
+	def defaults(extra: ScopedKey[_] => Seq[AbstractLogger]): LogManager  =  withLoggers(extra = extra)
 
 	def defaultScreen: AbstractLogger = ConsoleLogger()
 	def defaultBacked(useColor: Boolean): PrintWriter => AbstractLogger =
@@ -24,13 +25,13 @@ object LogManager
 
 	def withScreenLogger(mk: => AbstractLogger): LogManager = withLoggers(mk)
 	
-	def withLoggers(screen: => AbstractLogger = defaultScreen, backed: PrintWriter => AbstractLogger = defaultBacked(ConsoleLogger.formatEnabled)): LogManager =
+	def withLoggers(screen: => AbstractLogger = defaultScreen, backed: PrintWriter => AbstractLogger = defaultBacked(ConsoleLogger.formatEnabled), extra: ScopedKey[_] => Seq[AbstractLogger] = _ => Nil): LogManager =
 		new LogManager {
 			def apply(data: Settings[Scope], task: ScopedKey[_], to: PrintWriter): Logger =
-				defaultLogger(data, task, screen, backed(to))
+				defaultLogger(data, task, screen, backed(to), extra(task).toList)
 		}
 
-	def defaultLogger(data: Settings[Scope], task: ScopedKey[_], console: AbstractLogger, backed: AbstractLogger): Logger =
+	def defaultLogger(data: Settings[Scope], task: ScopedKey[_], console: AbstractLogger, backed: AbstractLogger, extra: List[AbstractLogger]): Logger =
 	{
 		val scope = task.scope
 		def getOr[T](key: AttributeKey[T], default: T): T = data.get(scope, key) getOrElse default
@@ -39,9 +40,9 @@ object LogManager
 		val screenTrace = getOr(traceLevel.key, -1)
 		val backingTrace = getOr(persistTraceLevel.key, Int.MaxValue)
 
-		val multi = new MultiLogger(console :: backed :: Nil)
+		val multi = new MultiLogger(console :: backed :: extra)
 			// sets multi to the most verbose for clients that inspect the current level
-		multi setLevel Level.union(backingLevel, screenLevel)
+		multi setLevel Level.unionAll(backingLevel :: screenLevel :: extra.map(_.getLevel))
 			// set the specific levels
 		console setLevel screenLevel
 		backed setLevel backingLevel

util/log/Level.scala

@@ -16,6 +16,7 @@ object Level extends Enumeration
 	val SuccessLabel = "success"
 
 	def union(a: Value, b: Value) = if(a.id < b.id) a else b
+	def unionAll(vs: Seq[Value]) = vs reduceLeft union
 
 	/** Returns the level with the given name wrapped in Some, or None if no level exists for that name. */
 	def apply(s: String) = values.find(s == _.toString)