Scala Logging

Scala Logging is a convenient and performant logging library wrapping logging libraries like SLF4J and potentially others.

It's convenient, because you can simply call log methods without checking whether the respective log level is enabled:

logger.debug(s"Some $expensive message!")

It's performant, because thanks to Scala macros the check-enabled-idiom is applied, just like writing this more involved code:

if (logger.isDebugEnabled) logger.debug(s"Some $expensive message!")

Prerequisites

• Java 6 or higher
• Scala 2.11
• Logging backend compatible with SLF4J, e.g. Logback

Getting Scala Logging

Scala Logging is published to Sonatype OSS and Maven Central:

• Group id / organization: com.typesafe.scala-logging
• Modules (artifact id / name):
  • scala-logging-api if you just need the API
  • scala-logging-slf4j for the SLF4J-backed implementation
• Latest release version is 2.0.2

The following example shows how to add a dependency to the latest version of Scala Logging to your sbt build definition:

libraryDependencies += "com.typesafe.scala-logging" %% "scala-logging-slf4j" % "2.0.2"

Using Scala Logging

API

Scala Logging comes with a thin API layer, packaged in the scala-logging-api module, which is independent of a particular logging library. The com.typesafe.scalalogging package contains the following members:

The Logger trait declares abstract logging methods like error, info, etc.

The Logging trait declares the abstract logger member of type Logger, i.e. requires the class, into which this trait is mixed, to define a Logger.

SLF4J-backed implementation

The implementation for SLF4J is packaged in the scala-logging-slf4j module. The com.typesafe.scalalogging.slf4j package contains the following members:

The Logger class implements the Logger trait from the API package. It wraps an underlying SLF4J logger. Hence, in order to create a Logger, you have to pass a SLF4J logger to the apply factory method defined in the Logger companion object:

val logger = Logger(LoggerFactory getLogger "name")

The LazyLogging and StrictLogging traits implement the Logging trait from the API package. They define the logger member as a lazy or strict value respectively. In both cases the underlying SLF4J logger is named like the class into which these traits are mixed:

class MyClass extends LazyLogging {
  logger.debug("This is very convenient ;-)")
}

Contribution policy

Contributions via GitHub pull requests are gladly accepted from their original author. Before we can accept pull requests, you will need to agree to the Typesafe Contributor License Agreement online, using your GitHub account.

License

This code is open source software licensed under the Apache 2.0 License.