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Objective-C literals for NSDictionary, NSArray, and NSNumber

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Re: Objective-C literals for NSDictionary, NSArray, and NSNumber

#31

Post by alextgordon »

rbrown46 wrote: post #28
pooriaazimi wrote: post #17

Earlier quoted context omitted.

> ...so it only is available to those in Apple's Developer Program. correction: Apple's Mac developer program. I'm an iOS developer and I don't see Xcode 4.4 in my dashboard.

This is the second time (to my knowledge, may have been going on for a while) that an Xcode beta has been made available to only one of the two (Mac and iOS) developer programs. The Xcode 4.3 beta was only available to iOS developers -- despite containing bug fixes and improvements useful to developers on both platforms. Now the Xcode 4.4 beta is only available to Mac developers. I really don't see the logic in withh…

Xcode 4.2 was also only available to iOS developers.

Xcode 4.1 was part of the Lion pre-release, so I don't think that iOS developers got it during beta, though apparently it was made available for SL users a few weeks after Lion shipped.

It at least makes sense to limit the betas to the Mac program only if the tool in question only works on a prerelease OS (I assume that's the case with 4.4 and ML). But limiting it to iOS developers only makes no technical sense at all.

Edit: 4.4 works on 10.7.3+, so yeah, this is just the usual bullshit.

Re: Objective-C literals for NSDictionary, NSArray, and NSNumber

#32

Post by ary »

openbear wrote: post #29

I'm glad to see these additions, but the syntax for an NSArray literal bugs me. When I want an array literal in C, I'd write ... int foo[] = { 1, 2, 3, 4, 5}; ... but in Objective-C, for an NSArray literal I'd write ... NSArray *bar = @[o1, o2, o3]; Why did they choose '[' over '{'? Oddly enough, NSDictionary uses '{'. I feel like the syntax for an NSString literal is more natural (as a C developer). NSString *baz =…

> Why did they choose '[' over '{'? Oddly enough, NSDictionary uses '{'.

Who knows, but it seems to mirror Python in that respect. Being a fan of Python I can only approve.

Re: Objective-C literals for NSDictionary, NSArray, and NSNumber

#33

Post by thought_alarm »

frou_dh wrote: post #5

Does this come courtesy of a new version of the Objective-C language? The definition of ObjC confuses me a bit. It's said to be a superset of C - but which C? C89? C99? GNU-C-Something?

Obj-C is essentially a preprocessor on top of a C compiler. Whether that C compiler is C89, C99, or C++11 is up to you.

Obj-C also includes the Foundation classes that were originally introduced with the OpenStep SDK in 1994 (NSObject, NSString, NSNumber, NSArray, NSRunLoop, NSAutoreleasePool, etc.).

Re: Objective-C literals for NSDictionary, NSArray, and NSNumber

#34

Post by frou_dh »

thought_alarm wrote: post #33
frou_dh wrote: post #5

Does this come courtesy of a new version of the Objective-C language? The definition of ObjC confuses me a bit. It's said to be a superset of C - but which C? C89? C99? GNU-C-Something?

Obj-C is essentially a preprocessor on top of a C compiler. Whether that C compiler is C89, C99, or C++11 is up to you. Obj-C also includes the Foundation classes that were originally introduced with the OpenStep SDK in 1994 (NSObject, NSString, NSNumber, NSArray, NSRunLoop, NSAutoreleasePool, etc.).

Is it possible to see this straight C translation? Using Clang for example. I'm sort of aware of the "objc_msgSend" business, but would like to see more.

Talking of OpenStep, after seeing some of those NeXT videos on HN the other day, I found a torrent of OpenStep 4.2 incl the dev tools. It's a VMware image and boots and runs just fine. Pretty nifty. Then I noticed OpenStep 5.0 redirects to Mac OS X on Wikipedia!

Re: Objective-C literals for NSDictionary, NSArray, and NSNumber

#35

Post by 2mur »

ary wrote: post #32
openbear wrote: post #29

I'm glad to see these additions, but the syntax for an NSArray literal bugs me. When I want an array literal in C, I'd write ... int foo[] = { 1, 2, 3, 4, 5}; ... but in Objective-C, for an NSArray literal I'd write ... NSArray *bar = @[o1, o2, o3]; Why did they choose '[' over '{'? Oddly enough, NSDictionary uses '{'. I feel like the syntax for an NSString literal is more natural (as a C developer). NSString *baz =…

> Why did they choose '[' over '{'? Oddly enough, NSDictionary uses '{'. Who knows, but it seems to mirror Python in that respect. Being a fan of Python I can only approve.

Completely agree. Looks natural to me as a python/javascript guy

Re: Objective-C literals for NSDictionary, NSArray, and NSNumber

#36

Post by msbarnett »

natesm wrote: post #22

On one hand, it's nice, and it'll make coding in Obj-C nicer. On the other hand, it strengthens the coupling between Objective-C the language the Cocoa the framework, and I'm not sure how I feel about that. I do like it better than the property dot syntax though. (is a simple assignment to a struct member? is it an objc_msgSend of unknown complexity?)

This doesn't do much of anything to increase coupling to Cocoa.

It does represent yet another link between the language syntax and the Foundation framework (along with NSStrings, blocks, etc), but Foundation is effectively part of the language.

Re: Objective-C literals for NSDictionary, NSArray, and NSNumber

#38

Post by pjmlp »

demallien wrote: post #12
flyosity wrote: post #8

Earlier quoted context omitted.

Maybe I'm misunderstanding, but how much effort are you talking about here? Skipping @synthesize on properties or using literal syntax where/when it makes sense wouldn't cause much additional cognitive load and you don't have to convert old code to use the new sugar.

It's not as simple as that when you're planning for the long term. Firstly you need to examine the changes and make sure that they aren't going to create any compatability problems, of the type "if you activate this option, then you can no longer link to libraries that don't use this option". Garbage collection in particular had a lot of those sorts of problems. But even if you can convince yourself that it is just s…

Why should you rewrite working code?

Re: Objective-C literals for NSDictionary, NSArray, and NSNumber

#39

Post by Zev »

frou_dh wrote: post #34
thought_alarm wrote: post #33

Earlier quoted context omitted.

Obj-C is essentially a preprocessor on top of a C compiler. Whether that C compiler is C89, C99, or C++11 is up to you. Obj-C also includes the Foundation classes that were originally introduced with the OpenStep SDK in 1994 (NSObject, NSString, NSNumber, NSArray, NSRunLoop, NSAutoreleasePool, etc.).

Is it possible to see this straight C translation? Using Clang for example. I'm sort of aware of the "objc_msgSend" business, but would like to see more. Talking of OpenStep, after seeing some of those NeXT videos on HN the other day, I found a torrent of OpenStep 4.2 incl the dev tools. It's a VMware image and boots and runs just fine. Pretty nifty. Then I noticed OpenStep 5.0 redirects to Mac OS X on Wikipedia!

Quick example of calling a method that doesn't take any arguments and returns an object:

  id foo = [self bar];
is the same as:

  id foo = self.bar;
which is also the same as:

  id foo = [self performSelector:@selector(bar)];
or:

  IMP barImp = [self methodForSelector:@selector(bar)];
  id foo = barImp(self, @selector(bar); [1]
and finally:

  id foo = ((id)(id, SEL)objc_msgSend)(self, @selector(bar)); [2, 3, 4]
1. Because we're calling the IMP, or implementation, directly, we don't need a cast (like we do below, with objc_msgSend).

2. Casting the function is optional, but, helps to prevent things like endian differences and your return value getting mangled when using the same code on PPC and Intel. Not too big of a deal anymore.

3. There are actually two other varieties of objc_msgSend, depending on your return type — specifically, floating point calls should use objc_msgSend_fpret and calls that return a struct should use objc_msgSend_stret.

4. I hope I got this cast right, I didn't try to compile it.

Re: Objective-C literals for NSDictionary, NSArray, and NSNumber

#40

Post by bebop »

openbear wrote: post #29

I'm glad to see these additions, but the syntax for an NSArray literal bugs me. When I want an array literal in C, I'd write ... int foo[] = { 1, 2, 3, 4, 5}; ... but in Objective-C, for an NSArray literal I'd write ... NSArray *bar = @[o1, o2, o3]; Why did they choose '[' over '{'? Oddly enough, NSDictionary uses '{'. I feel like the syntax for an NSString literal is more natural (as a C developer). NSString *baz =…

I think they chose the [] for arrays and {} for dictionaries as that is the style that seems to be most popular right now. Python for instance uses this.
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