//

 //  KVUtils.h

 //  MYUtilities

 //

 //  Created by Jens Alfke on 2/25/08.

 //  Copyright 2008 Jens Alfke. All rights reserved.

 //

 #import <Cocoa/Cocoa.h>

 enum {

     MYKeyValueObservingOptionOnce = 1<<31,

     MYKeyValueObservingOptionDelayed = 1<<30

 };

 @interface Observance : NSObject

 {

     id _target;

     id _observed;

     NSString *_keyPath;

     NSKeyValueObservingOptions _options;

     SEL _action;

 }

 - (id) initWithTarget: (id)target 

                action: (SEL)action

              observed: (id)observed

               keyPath: (NSString*)keyPath 

               options: (NSKeyValueObservingOptions)options;

 - (void) stopObserving;

 @property (readonly) id observed;

 @property (readonly) NSString* keyPath;

 @end

 @interface Observer : NSObject

 {

     id _target;

     NSMutableArray *_observances;

 }

 - (id) initWithTarget: (id)target;

 @property (readonly) id target;

 - (void) observe: (id)observed 

          keyPath: (NSString*)keyPath 

          options: (NSKeyValueObservingOptions)options

           action: (SEL)action;

 - (void) observe: (id)observed 

          keyPath: (NSString*)keyPath 

           action: (SEL)action;

 /** observed or keyPath may be nil, meaning wildcard */

 - (void) stopObserving: (id)observedOrNil keyPath: (NSString*)keyPathOrNil;

 - (void) stopObserving: (id)observed;

 - (void) stopObserving;

 @end