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Truffle/Instrumentation: significant rearrangement (including moved class) and extension of the Truffle Instrumentation Framework. New interfaces include DebugContext (which can be attached to the ExecutionContext), through which access is provided to possibly language-specific (a) node instrumentation, (b) debug services manager, (c) notification when programs halt, (d) display of language values, and (e) display of variable identifiers.
author Michael Van De Vanter <michael.van.de.vanter@oracle.com>
date Mon, 03 Feb 2014 20:58:23 -0800
parents 0fbee3eb71f0
children
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/*
 * Copyright (c) 2013 Oracle and/or its affiliates. All rights reserved. This
 * code is released under a tri EPL/GPL/LGPL license. You can use it,
 * redistribute it and/or modify it under the terms of the:
 *
 * Eclipse Public License version 1.0
 * GNU General Public License version 2
 * GNU Lesser General Public License version 2.1
 */
package com.oracle.truffle.ruby.runtime;

/**
 * The {@link UndefinedPlaceholder} is a value that represents an undefined value in Ruby. This is
 * used to differentiate between nil and the true absence of a value, such as an argument that has
 * not been passed.
 */
public final class UndefinedPlaceholder {

    public static final UndefinedPlaceholder INSTANCE = new UndefinedPlaceholder();

    private UndefinedPlaceholder() {
    }

}