There are a few *.java files in the source tree of Scala in the scala.runtime directory.
Those files seem to be very simple, e. g. DoubleRef.java
looks like this:
package scala.runtime;
public class DoubleRef implements java.io.Serializable {
private static final long serialVersionUID = 8304402127373655534L;
public double elem;
public DoubleRef(double elem) { this.elem = elem; }
public String toString() { return java.lang.Double.toString(elem); }
}
Is there any reason why those classes can't be defined in Scala?
Just a guess, too: there is no Scala construct that compiles to a public field — public var
s in Scala compile to a private field and to a public accessor and mutator. As I imagine that those *Ref
classes are used extensively, this could be an optimization to avoid frequent method calls and replace them with direct field access.