Blocked-C

Update: It appears that the original article has been removed, and has been superseded by material at: http://developer.apple.com/mac/articles/cocoa/introblocksgcd.html. The original article had more on the Cocoa block APIs and gave a refreshingly honest assessment of the for-loop vs. Block-iteration comparison.

While the news that Apple is adding blocks to C and Objective-C in the SnowLeopard time frame has been around for some time, a recent article shed some light on the actual API.

While there probably are some places where Objective-C blocks can be useful, I am not really impressed. In the following samples, red is used to show noise, meaning code that is just there to make the compiler happy.

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NSMutableArray *filteredItems= [NSMutableArray array];
[items enumerateObjectsWithOptions:0 withBlock:
    ^(id item, NSUInteger index, BOOL *stop) {
        [filteredItems addObject:[item stringByAppendingString:@"suffix"]];
    }
];

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As you can see, the version using blocks is very, very noisy, both syntactically and semantically, especially compared with the HOM version:

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[[items collect] stringByAppendingString:@"suffix"];

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No prizes for guessing which I'd prefer. To put some numbers on my preference: 234 characters vs. 52, 19 tokens vs. 3, 5 lines vs. 1. In fact, even a plain old C for-loop is more compact and less noisy than our "modern" blocked version:

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NSMutableArray *filteredItems= [NSMutableArray array];
for (int i=0; i < [items count]; i++ ) {
     [filteredItems addObject:[items objectAtIndex:i] stringByAppendingString:@"suffix"];
    }
];

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