Scala (19): Lazy

lazy means it only be initialized for the first visit, not when its class is initialized. lazy is suitable for some scenario, for example, the cost time on initializing is very long.

Here is an example to get Scala version number from github.

class ScalaCurrentVersion(val url: String) {
  lazy val source = {
    println("fetching from url...")
    scala.io.Source.fromURL(url).getLines().toList
  }
  lazy val majorVersion = source.find(_.contains("version.major"))
  lazy val minorVersion = source.find(_.contains("version.minor"))
}
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