Package com.oracle.truffle.sl.runtime

Class SLNull

java.lang.Object

com.oracle.truffle.sl.runtime.SLNull

All Implemented Interfaces:

com.oracle.truffle.api.interop.TruffleObject

public final class SLNull
extends Object
implements com.oracle.truffle.api.interop.TruffleObject

The SL type for a null (i.e., undefined) value. In Truffle, it is generally discouraged to use the Java null value to represent the guest language null value. It is not possible to specialize on Java null (since you cannot ask it for the Java class), and there is always the danger of a spurious NullPointerException. Representing the guest language null as a singleton, as in this class, is the recommended practice.

Field Summary

Fields

Modifier and Type	Field	Description
static final SLNull	SINGLETON	The canonical value to represent null in SL.

Method Summary

Modifier and Type	Method	Description
String	toString()	This method is, e.g., called when using the null value in a string concatenation.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Details

SINGLETON

public static final SLNull SINGLETON

The canonical value to represent null in SL.

Method Details

toString

public String toString()

This method is, e.g., called when using the null value in a string concatenation. So changing it has an effect on SL programs.

Overrides:

toString in class Object