NSKeyValueCoding.ValueAccessor (WebObjects 5.4.2 Reference)

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WebObjects 5.4.2

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com.webobjects.foundation
Class NSKeyValueCoding.ValueAccessor

java.lang.Object
  com.webobjects.foundation.NSKeyValueCoding.ValueAccessor

Enclosing interface:: NSKeyValueCoding

public abstract static class NSKeyValueCoding.ValueAccessor
extends Object
extends Object

NSKeyValueCoding.ValueAccessor is an abstract class that establishes a mechanism by which NSKeyValueCoding can operate on object's package access instance variables.

By default, Foundation's implementations of NSKeyValueCoding cannot access package access instance variables. If you have package access instance variables in your NSKeyValueCoding objects, you can make them available to key-value coding in one of the three ways:

Implement public setKey and key accessor methods for those instance variables that set and return the instance variable's values.
Make the instance variables public.
Add a subclass of NSKeyValueCoding.ValueAccessor named KeyValueCodingProtectedAccessor to your package. This class provides a mechanism to manipulate package access instance variables.

The best solution is to implement accessor methods or to make the instance variables public. However, if you have a lot of classes with a lot of package access instance variables, you can use the short-term solution that NSKeyValueCoding.ValueAccessor provides until you make the necessary changes to your code.

To use NSKeyValueCoding.ValueAccessor's mechanism, simply create a class in your package as follows:

           <blockquote>

           package yourPackage;
           import java.lang.reflect.*;
           import com.webobjects.foundation.*;

           public class KeyValueCodingProtectedAccessor extends
                                                   NSKeyValueCoding.ValueAccessor {

             public KeyValueCodingProtectedAccessor() {
               super();
             }

             public Object fieldValue(Object object, Field field) throws
                              IllegalArgumentException, IllegalAccessException {
               return field.get(object);
             }

             public void setFieldValue(Object object, Field field, Object value) throws
                              IllegalArgumentException, IllegalAccessException {
               field.set(object, value);
             }

             public Object methodValue(Object object, Method method) throws
                   IllegalArgumentException, IllegalAccessException,
                                                        java.lang.reflect.InvocationTargetException {
               return method.invoke(object);
             }

             public void setMethodValue(Object object, Method method, Object value) throws
                   IllegalArgumentException, IllegalAccessException,
                                                           java.lang.reflect.InvocationTargetException {
               method.invoke(object, new Object[] {value});
             }
           }
           </blockquote>

See Also:: NSKeyValueCoding

Constructor Summary
`NSKeyValueCoding.ValueAccessor()` empty constructor is required for subclasses implementing the ValueAccessor interface

Method Summary
`abstract Object`	`fieldValue(Object object, Field field)`
`abstract Object`	`methodValue(Object object, Method method)` Uses `method` to return `object`'s corresponding property value.
`static NSKeyValueCoding.ValueAccessor`	`protectedAccessorForPackageNamed(String packageName)`
`static void`	`removeProtectedAccessorForPackageNamed(String packageName)` Removes (unregisters) the value accessor for the package identified by `packageName`.
`abstract void`	`setFieldValue(Object object, Field field, Object value)` Sets `object`'s `field` value to `value`.
`abstract void`	`setMethodValue(Object object, Method method, Object value)` Uses `method` to set `object`'s corresponding property to `value`.
`static void`	`setProtectedAccessorForPackageNamed(NSKeyValueCoding.ValueAccessor valueAccessor, String packageName)` Sets the value accessor for the package identified by `packageName` to `valueAccessor`.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail