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Forest-of-actors runtime supporting real-time systems and real-time recoding - bringing aspects of Erlang, Smalltalk and Extempore to Java.

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/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 2023 Neil C Smith.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License version 3 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
 * version 3 for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License version 3
 * along with this work; if not, see http://www.gnu.org/licenses/
 *
 *
 * Please visit https://www.praxislive.org if you need additional information or
 * have any questions.
 */
package org.praxislive.code;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * Base class for user rewritable Root code.
 */
public class CodeRootDelegate extends CodeDelegate {

    /**
     * Hook called whenever the delegate needs to be initialized. Will be called
     * when the root is started, and any time the code is updated. Because this
     * code is called in a running root, the code should be suitable for
     * real-time usage.
     */
    public void init() {
    }

    /**
     * Mark a field referencing an interface implementation to be wrapped by an
     * interface proxy, and used to drive updates of the root. Any call to the
     * proxy will cause a root update on the calling thread, prior to calling
     * through to the interface implementation.
     * 
     * By default, polling for messages will be done in a background thread
     * between calls to the interface - code may execute outside of calls to the
     * interface. Updates may also be forced on the background thread if the
     * interface has not been called in some time.
     * 

     * The field must refer to the desired implementation after delegate
     * instantiation - the easiest way is to initialize the field with the right
     * value. The field value will be wrapped in a proxy, which will be set as
     * the new field value during code attachment. This way the implementation
     * of the interface may be freely changed, while the reference passed to
     * external code remains constant.
     * 
     * The field type must be that of the desired interface rather than its
     * implementation.
     */
    @Retention(RetentionPolicy.RUNTIME)
    @Target(ElementType.FIELD)
    public @interface Driver {
    }

}