yield(self) pattern implemented with objective-C blocks

yield-self.m

//
// yield(self) pattern implemented using objective-C blocks
// (not as pretty as Ruby...)
// 
// compile:
// llvm-gcc-4.2 -o yield-self -framework Foundation yield-self.m

#import <Foundation/Foundation.h>

@class MyClass;

typedef id (^YieldSelfBlock)(MyClass *instance);

@interface MyClass : NSObject
{
    NSString* _name;
}

@property (nonatomic, copy) NSString *name;

+ (id)instanceUsingBlock:(YieldSelfBlock)block;
+ (id)newUsingBlock:(YieldSelfBlock)block;

- (id)initUsingBlock:(YieldSelfBlock)block;

@end

@implementation MyClass

@synthesize name = _name;

+ (id)instanceUsingBlock:(YieldSelfBlock)block
{
    return [[[self alloc] initUsingBlock:block] autorelease];
}

+ (id)newUsingBlock:(YieldSelfBlock)block
{
    return [[self alloc] initUsingBlock:block];
}

- (id)initUsingBlock:(YieldSelfBlock)block;
{
    if ( (self != [super init]) )
    {
        [self release];
        return nil;
    }
    
    if ( block )
        block(self);
    
    return self;
}

- (void)dealloc
{
    [_name release]; _name = nil;
    [super dealloc];
}

@end

int main(int argc, char** argv)
{
    MyClass *example = [MyClass newUsingBlock:^id (MyClass *obj){
        obj.name = @"Brian";
    }];
        
    NSLog(@"example: %@; name = %@", example, example.name);
    
    [example release];  
    
    return 0;
}