com.webobjects.foundation
Class NSKeyValueCoding.ValueAccessor

java.lang.Object
  |
  +--com.webobjects.foundation.NSKeyValueCoding.ValueAccessor

Enclosing class:

NSKeyValueCoding

public abstract static class NSKeyValueCoding.ValueAccessor

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:

 

 
 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,
                                              InvocationTargetException {
     return method.invoke(object, null);
   }

   public void setMethodValue(Object object, Method method, Object value) throws
         IllegalArgumentException, IllegalAccessException,
                                                 InvocationTargetException {
     method.invoke(object, new Object[] {value});
   }
 }
 
 

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

NSKeyValueCoding.ValueAccessor

public NSKeyValueCoding.ValueAccessor()

empty constructor is required for subclasses implementing the ValueAccessor interface

Method Detail

fieldValue

public abstract Object fieldValue(Object object,
                                  Field field)
                           throws IllegalArgumentException,
                                  IllegalAccessException

Parameters:

object - the object whose package access instance variables are to be operated on

field - the value of object's field

Returns:

object's field

Throws:

IllegalArgumentException -

IllegalAccessException -

methodValue

public abstract Object methodValue(Object object,
                                   Method method)
                            throws IllegalArgumentException,
                                   IllegalAccessException,
                                   InvocationTargetException

Uses method to return object's corresponding property value.

Parameters:

object - the object whose package access instance variables are to be operated on

method - instance variables of the object

Returns:

object's corresponding property value

Throws:

IllegalArgumentException -

IllegalAccessException -

java.lang.InvocationTargetException -

protectedAccessorForPackageNamed

public static NSKeyValueCoding.ValueAccessor protectedAccessorForPackageNamed(String packageName)

Parameters:

packageName - the package identified to be operated on

Returns:

the value accessor for the package identified by packageName

removeProtectedAccessorForPackageNamed

public static void removeProtectedAccessorForPackageNamed(String packageName)

Removes (unregisters) the value accessor for the package identified by packageName.

Parameters:

packageName - the package identified to be operated on

setFieldValue

public abstract void setFieldValue(Object object,
                                   Field field,
                                   Object value)
                            throws IllegalArgumentException,
                                   IllegalAccessException

Sets object's field value to value.

Parameters:

object - the object whose package access instance variables are to be operated on

field - object's property whose value is to be set

value - object's property identified by field is set to this

Throws:

IllegalArgumentException -

IllegalAccessException -

setMethodValue

public abstract void setMethodValue(Object object,
                                    Method method,
                                    Object value)
                             throws IllegalArgumentException,
                                    IllegalAccessException,
                                    InvocationTargetException

Uses method to set object's corresponding property to value.

Parameters:

object - the object whose package access instance variables are to be operated on

method - instance variables of the object

value - object's field identified by field is set to this

Throws:

IllegalArgumentException -

IllegalAccessException -

java.lang.InvocationTargetException -

setProtectedAccessorForPackageNamed

public static void setProtectedAccessorForPackageNamed(NSKeyValueCoding.ValueAccessor valueAccessor,
                                                       String packageName)

Sets the value accessor for the package identified by packageName to valueAccessor.

Parameters:

valueAccessor - the value accessor for the package identified by packageName

packageName - the value accessor for the package is identified by this