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Groovy example source code file (ExpandoMetaClassCreationHandle.java)

This example Groovy source code file (ExpandoMetaClassCreationHandle.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Groovy tags/keywords

class, expandometaclass, expandometaclasscreationhandle, expandometaclasscreationhandle, metaclass, metaclass, metaclasscreationhandle, metaclasscreationhandle, metaclassregistry, metaclassregistry

The Groovy ExpandoMetaClassCreationHandle.java source code

/*
 * Copyright 2003-2007 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package groovy.lang;

import groovy.lang.MetaClassRegistry.MetaClassCreationHandle;
import org.codehaus.groovy.reflection.ClassInfo;

/**
 * <p>A handle for the MetaClassRegistry that changes all classes loaded into the Grails VM
 * to use ExpandoMetaClass instances
 *
 * <p>The handle should be registered with the Groovy runtime before Groovy loads, for example
 * in your main method.
 *
 * <code>GroovySystem.metaClassRegistry.metaClassCreationHandle = new ExpandoMetaClassCreationHandle()
 *
 * @see groovy.lang.MetaClassRegistry
 * @see groovy.lang.MetaClassRegistry.MetaClassCreationHandle
 * @see org.codehaus.groovy.runtime.metaclass.MetaClassRegistryImpl#setMetaClassCreationHandle(groovy.lang.MetaClassRegistry.MetaClassCreationHandle)
 *
 * @author Graeme Rocher
 * @since 1.5
 */
public class ExpandoMetaClassCreationHandle extends MetaClassCreationHandle {

    public static final ExpandoMetaClassCreationHandle instance = new ExpandoMetaClassCreationHandle();

    /* (non-Javadoc)
     * @see groovy.lang.MetaClassRegistry.MetaClassCreationHandle#create(java.lang.Class, groovy.lang.MetaClassRegistry)
     */
    protected MetaClass createNormalMetaClass(Class theClass, MetaClassRegistry registry) {
        if(theClass != ExpandoMetaClass.class) {
            return new ExpandoMetaClass(theClass, true, true);
        }
        else {
            return super.createNormalMetaClass(theClass, registry);
        }
    }

    /**
     * Registers a modified ExpandoMetaClass with the creation handle
     *
     * @param emc The EMC
     */
    public void registerModifiedMetaClass(ExpandoMetaClass emc) {
        final Class klazz = emc.getJavaClass();
        GroovySystem.getMetaClassRegistry().setMetaClass(klazz,emc);
    }

    public boolean hasModifiedMetaClass(ExpandoMetaClass emc) {
        return emc.getClassInfo().getModifiedExpando() != null;
    }

    /**
     * <p>Enables the ExpandoMetaClassCreationHandle with the registry
     *
     * <code>ExpandoMetaClassCreationHandle.enable();
     *
     */
    public static void enable() {
        final MetaClassRegistry metaClassRegistry = GroovySystem.getMetaClassRegistry();
        synchronized (metaClassRegistry) {
            if (metaClassRegistry.getMetaClassCreationHandler() != instance) {
                ClassInfo.clearModifiedExpandos();
                metaClassRegistry.setMetaClassCreationHandle(instance);
            }
        }
    }

    public static void disable() {
        final MetaClassRegistry metaClassRegistry = GroovySystem.getMetaClassRegistry();
        synchronized (metaClassRegistry) {
            if (metaClassRegistry.getMetaClassCreationHandler() == instance) {
                ClassInfo.clearModifiedExpandos();
                metaClassRegistry.setMetaClassCreationHandle(new MetaClassCreationHandle());
            }
        }
    }
}

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