점프와 쉼없는 나아감

if (logger.isDebugEnabled()) {
    logger.debug(some.expensiveMethod());
}

//Logger.scala:
package corund.logger

import org.apache.log4j.Level

class Logger(cat: String) {
    val payload = org.apache.log4j.Logger.getLogger(cat)

    def debug(msg: => String) {
        if (payload.isDebugEnabled()) {
            debug(msg)
        }
    }

    def info(msg: => String) {
        if (payload.isInfoEnabled()) {
            info(msg)
        }
    }

    def warn(msg: => String) {
        if (payload.isEnabledFor(Level.WARN)) {
            warn(msg)
        }
    }
    // error 메서드 등 생략 ....
}

object Logger {
    def apply(cat: String): Logger = new Logger(cat)
}

//Logging.scala
package corund.run

import org.apache.log4j.BasicConfigurator
import org.apache.log4j.Level
import corund.logger.Logger

object Logging {
    def main(args: Array[String]) {
        BasicConfigurator.configure()
        org.apache.log4j.Logger.getRootLogger().setLevel(Level.WARN)
        val logger = Logger("corund.run.Logging")

        class Data(str: String) {
            def expensive() = {
                println("Invoked! - " + str)
                str
            }
        }

        val data = new Data("expensive object")

        logger.debug("debug: " + data.expensive())
        logger.info("info: " + data.expensive())
        logger.warn("warn: " + data.expensive())
        logger.error("error: " + data.expensive())
    }
}

I can honestly say if someone had shown me the Programming Scala book by by Martin Odersky, Lex Spoon & Bill Venners back in 2003 I'd probably have never created Groovy.

Conclusion:

Given that MrJava, MrJRuby and MrGroovy are all tipping Scala as javac's long term replacement, there might be something in it. So what are you waiting for; get the Programming Scala book or the O'Reilly Scala book and start having fun :)