WeakReferencingObject

Can anyone tell me why this example is allowed to ignore the "must be the same size" rule of poseAsClass: by adding an extra int to the definition? Incidentally, I reformatted the code to stop it adding a horizontal scrollbar on my screen. --General/KritTer

Have written it, I can’t tell you that. It compiles… or did… maybe bit rot has set in, I’m not certain. As it is, I don’t really have any use for it, so it’s fallen by the proverbial wayside; thank you for the formatting, however (the horizontal scrollbar is bloody evil). – General/RobRix

General/FDWeakReferencingObject is a nice little class which poses as General/NSObject to give all objects some lovely little General/WeakReferencing methods.

Class reference:

+(void)setupWeakReferencing

This does absolutely nothing except insure that the runtime has sent the +initialize method to the class. Use this to allow you to use weak referencing everywhere. This is the only method you’ll need to call directly.

-(id)weakRetain

Increments the weakRetainCount and retainCount.

-(void)weakRelease

Decrements the weakRetainCount and retainCount.

-(void)release

This is an extension of General/NSObject’s -release method (that is, it calls General/NSObject’s -release method within the implementation). All it adds is a short block of code to check whether or not the weakRetainCount and retainCount are the same, and if they are, it -releases and -weakReleases self till both counts are zero.

-(unsigned int)weakRetainCount

Returns weakRetainCount, which is the number of weak retains that have been made.

-(id)description

Returns a description of the instance. This varies from General/NSObject’s version by putting the weakRetainCount in along with the class name.

I have provided the code for your fancy (this is newer than the code on my site):

From General/FDWeakReferencingObject.h

// v1.2

#import <Foundation/Foundation.h>

void setupWeakReferencing(); // sets up weak referencing by making certain that the // General/FDWeakReferencing Class has had a chance to pose as General/NSObject. // It does this by allocating and releasing a temporary // object, so we know that the runtime has sent the +initialize // message to the class.

@interface General/FDWeakReferencingObject : General/NSObject { unsigned int weakRetainCount; } +(void)initialize; +(void)setupWeakReferencing;

-(id)weakRetain; -(void)release; -(void)weakRelease;

-(unsigned int)weakRetainCount;

-(id)description; @end

From General/FDWeakReferencingObject.m

// v1.2

#import “General/FDWeakReferencingObject.h”

@implementation General/FDWeakReferencingObject

(void)initialize { static BOOL tooLate = NO; if (tooLate == NO) { General/[FDWeakReferencingObject poseAsClass:General/[NSObject class]]; tooLate = YES; } }

+(void)setupWeakReferencing { // that’s all we need to get it to work. empty. not a thing further. //life is sweet. }

-(void)__incrementCount { weakRetainCount++; }

-(void)__decrementCount { weakRetainCount–; }

-(id)weakRetain { [self __incrementCount]; return [self retain]; }

-(void)release { if([self retainCount] == [self weakRetainCount]) { unsigned int counter = 0; for(counter = 0; counter < [self retainCount]; counter++) { [self weakRelease]; [super release]; } } else { [super release]; } }

-(void)weakRelease { [self __decrementCount]; [self release]; }

-(unsigned int)weakRetainCount { return weakRetainCount; }

-(id)description { General/NSMutableString *descriptionString = General/[[NSMutableString alloc] init];

[descriptionString appendFormat:
    @"Instance of %@ with a weakRetainCount of %i",
    [self class], [self weakRetainCount]];

return [descriptionString autorelease]; }

@end

void setupWeakReferencing() { static BOOL hasBeenSetUp = NO;

if(hasBeenSetUp == NO)
{
	General/[FDWeakReferencingObject setupWeakReferencing];
} }

– General/RobRix

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