home | career | drupal | java | mac | mysql | perl | scala | uml | unix

Groovy example source code file (MetaObjectProtocol.java)

This example Groovy source code file (MetaObjectProtocol.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, list, list, metamethod, metaobjectprotocol, metaproperty, metaproperty, object, object, string, string, util

The Groovy MetaObjectProtocol.java source code

/*
 * Copyright 2003-2009 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 java.util.List;

/**
 * <p>An interface that defines the API usable by clients of Groovy's Meta Object Protocol (MOP). These methods are
 * implemented by the reference implementation of the {@link groovy.lang.MetaClass} interface.</p>
 *
 * @see MetaClassImpl
 *
 * @author John Wilson
 * @author Graeme Rocher
 */
public interface MetaObjectProtocol {

    /**
     * Obtain a list of all meta properties available on this meta class
     *
     * @see groovy.lang.MetaProperty
     * @return A list of MetaProperty instances
     */
    List<MetaProperty> getProperties();
    /**
     * Obtain a list of all the meta methods available on this meta class
     *
     * @see groovy.lang.MetaMethod
     * @return A list of MetaMethod instances
     */
    List<MetaMethod> getMethods();
    
    /**
     * <p>Returns an object satisfying Groovy truth if the implementing MetaClass responds to
     * a method with the given name and arguments types.
     *
     * <p>Note that this method's return value is based on realised methods and does not take into account
     * objects or classes that implement invokeMethod or methodMissing
     *
     * <p>This method is "safe" in that it will always return a value and never throw an exception
     *
     * @param obj The object to inspect
     * @param name The name of the method of interest
     * @param argTypes The argument types to match against
     * @return A List of MetaMethods matching the argument types which will be empty if no matching methods exist
     */
    List<MetaMethod> respondsTo(Object obj, String name, Object[] argTypes);

    /**
     * <p>Returns an object satisfying Groovy truth if the implementing MetaClass responds to
     * a method with the given name regardless of arguments. In other words this method will
     * return for foo() and foo(String).
     *
     * <p>Note that this method's return value is based on realised methods and does not take into account
     * objects or classes that implement invokeMethod or methodMissing
     *
     * <p>This method is "safe" in that it will always return a value and never throw an exception
     *
     * @param obj The object to inspect
     * @param name The name of the method of interest
     * @return A List of MetaMethods which will be empty if no methods with the given name exist
     */
    List<MetaMethod> respondsTo(Object obj, String name);

    /**
     * <p>Returns true of the implementing MetaClass has a property of the given name
     *
     * <p>Note that this method will only return true for realised properties and does not take into
     * account implementation of getProperty or propertyMissing
     *
     * @param obj The object to inspect
     * @param name The name of the property
     * @return The MetaProperty or null if it doesn't exist
     */
    MetaProperty hasProperty(Object obj, String name);

    /**
     * Returns a MetaProperty for the given name or null if it doesn't exist
     *
     * @param name The name of the MetaProperty
     * @return A MetaProperty or null
     */
    MetaProperty getMetaProperty(String name);

    /**
     * Retrieves a static MetaMethod for the given name and argument values, using the types of the arguments
     * to establish the chosen MetaMethod
     *
     * @param name The name of the MetaMethod
     * @param args The argument types
     * @return A MetaMethod or null if it doesn't exist
     */
    MetaMethod getStaticMetaMethod(String name, Object[] args);


    /**
     * Retrieves an instance MetaMethod for the given name and argument values, using the types of the
     * argument values to establish the chosen MetaMethod
     *
     * @param name The name of the MetaMethod
     * @param args The argument types
     * @return A MetaMethod or null if it doesn't exist
     */
    MetaMethod getMetaMethod(String name, Object[] args);

    /**
     * Retrieves that Java Class that the attached Meta behaviours apply to
     *
     * @return The java.lang.Class instance
     */
    Class getTheClass();

    /**
     * Invokes a constructor for the given arguments. The MetaClass will attempt to pick the best argument which
     * matches the types of the objects passed within the arguments array
     *
     * @param arguments The arguments to the constructor
     * @return An instance of the java.lang.Class that this MetaObjectProtocol object applies to
     */
    Object invokeConstructor(Object[] arguments);

    /**
     * <p>Invokes a method on the given Object with the given name and arguments. The MetaClass will attempt to pick
     * the best method for the given name and arguments. If a method cannot be invoked a MissingMethodException will be
     * thrown.</p>
     *
     *
     * @see groovy.lang.MissingMethodException
     *
     * @param object The instance which the method is invoked on
     * @param methodName The name of the method
     * @param arguments The arguments to the method
     * @return The return value of the method which is null if the return type is void
     */
    Object invokeMethod(Object object, String methodName, Object[] arguments);

    /**
     * <p>Invokes a method on the given object, with the given name and single argument.

* * @see #invokeMethod(Object, String, Object[]) * * @param object The Object to invoke the method on * @param methodName The name of the method * @param arguments The argument to the method * @return The return value of the method which is null if the return type is void */ Object invokeMethod(Object object, String methodName, Object arguments); /** * <p>Invokes a static method on the given Object with the given name and arguments.

* * <p> The Object can either be an instance of the class that this * MetaObjectProtocol instance applies to or the java.lang.Class instance itself. If a method cannot be invoked * a MissingMethodException is will be thrown</p> * * @see groovy.lang.MissingMethodException * * @param object An instance of the class returned by the getTheClass() method or the class itself * @param methodName The name of the method * @param arguments The arguments to the method * @return The return value of the method which is null if the return type is void */ Object invokeStaticMethod(Object object, String methodName, Object[] arguments); /** * <p>Retrieves a property of an instance of the class returned by the getTheClass() method.

* * <p>What this means is largely down to the MetaClass implementation, however the default case would result * in an attempt to invoke a JavaBean getter, or if no such getter exists a public field of the instance.</p> * * @see MetaClassImpl * * @param object An instance of the class returned by the getTheClass() method * @param property The name of the property to retrieve the value for * @return The properties value */ Object getProperty(Object object, String property); /** * <p>Sets a property of an instance of the class returned by the getTheClass() method.

* * <p>What this means is largely down to the MetaClass implementation, however the default case would result * in an attempt to invoke a JavaBean setter, or if no such setter exists to set a public field of the instance.</p> * * @see MetaClassImpl * * @param object An instance of the class returned by the getTheClass() method * @param property The name of the property to set * @param newValue The new value of the property */ void setProperty(Object object, String property, Object newValue); /** * <p>Retrieves an attribute of an instance of the class returned by the getTheClass() method.

* * <p>What this means is largely down to the MetaClass implementation, however the default case would result * in attempt to read a field of the instance.</p> * * @see MetaClassImpl * * @param object An instance of the class returned by the getTheClass() method * @param attribute The name of the attribute to retrieve the value for * @return The attribute value */ Object getAttribute(Object object, String attribute); /** * <p>Sets an attribute of an instance of the class returned by the getTheClass() method.

* * <p>What this means is largely down to the MetaClass implementation, however the default case would result * in an attempt to set a field of the instance.</p> * * @see MetaClassImpl * * @param object An instance of the class returned by the getTheClass() method * @param attribute The name of the attribute to set * @param newValue The new value of the attribute */ void setAttribute(Object object, String attribute, Object newValue); }

Other Groovy examples (source code examples)

Here is a short list of links related to this Groovy MetaObjectProtocol.java source code file:

new blog posts

 

Copyright 1998-2014 Alvin Alexander, alvinalexander.com
All Rights Reserved.