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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

#51

Post by __david__ »

bebop wrote: post #40
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.

And Perl. And Javascript. And Ruby. There's lots of precedent.

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

#52

Post by __david__ »

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 =…

Because presumably (I don't have the new XCode to check) you can do things like:

    [someObject dictArg:@{ a:@"B" } arrayArg:@[1,2,34]];
So if they were both using "{" to set them off the parser doesn't know which one you mean until it hits the first ":" (and it can't guess from the type when the type is "id"). Now that's not impossible to write a parser that looks ahead to figure out what you mean, but it's much easier to parse if they have completely different syntax from the outset. And the "{" vs "[" distinction is very standard amongst the higher level languages, even if it isn't in straight C.

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

#53

Post by ZenPsycho »

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?)

Are there any drawbacks/pitfalls involved in creating a compiler that translates these literals to some other data structure library (such as glib, for example)?

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

#54

Post by openbear »

bebop wrote: post #40
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.

When adding features to something, I tend to be a big fan of "when in Rome"[1]. If these were extensions to Python (or Ruby or JavaScript) then I would totally be for using '[' with arrays. As a C guy though, I would rather have seen them use '{' for NSArray and '[' for NSDictionary. Regardless, I'm glad to see this stuff added.

[1] http://en.wiktionary.org/wiki/when_in_Rome,_do_as_the_Romans...

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

#55

Post by zoul »

boucher wrote: post #46

We've been talking about similar changes to Objective-J for quite some time (we already have JavaScript literals that map more cleanly than C ones). The one thing we've discussed that I don't think made it here is a set literal. It would be nice to have sets treated in a more first class way, considering how often arrays are used when sets would be more appropriate.

Indeed. Even [NSDictionary allKeys] returns an array instead of a set.

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

#56

Post by aaronblohowiak »

___Calv_Dee___ wrote: post #30
Derbasti wrote: post #20

Well, I guess that was long overdue. Anyway, another nice step to bring Objective-C forward. It seems to develop into a nice combination of low-level, high-performance C and a pretty straightforward, dynamic, object system. In short, I vastly prefer its object system to C++, because it reasonably trades some performance for greater dynamisms and an easier syntax. It'll be interesting how Objective-C will develop.

I completely agree, it's great to see that the language continues to move forward and advance in it's OO design. It's especially nice that these forward steps do not hinder or reduce Obj-C's low-level functionality, leaving available the performance gains from it's use.

Exactly, gcd could have been objc but it is just a c extension!!

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

#57

Post by xsmasher »

openbear wrote: post #54
bebop wrote: post #40

Earlier quoted context omitted.

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.

When adding features to something, I tend to be a big fan of "when in Rome"[1]. If these were extensions to Python (or Ruby or JavaScript) then I would totally be for using '[' with arrays. As a C guy though, I would rather have seen them use '{' for NSArray and '[' for NSDictionary. Regardless, I'm glad to see this stuff added. [1] http://en.wiktionary.org/wiki/when_in_Rome,_do_as_the_Romans...

It's already custom in objc to use {} for dicts and [] for arrays when printing them out, unless I'm misremembering. It also matches the use of those characters in JSON, so it seems natural to me.

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

#58

Post by pjmlp »

yuhao wrote: post #47
glhaynes wrote: post #26

Earlier quoted context omitted.

It's never before fully struck me how cleanly the "Objective-C is too verbose" complaint really breaks down to two separate issues: one of them being that method names are long (which is arguably a plus) and the other being mostly comprised of the stuff that's apparently mostly taken care of with this release. Actually, I suppose there used to be a third, too: (auto)release/retain statements all over the place. As so…

ARC in XCode 4.2 takes care of the release/retain business!

Kind of. It does not apply to all Cocoa libraries and you need to follow certain conventions, otherwise the compiler will fail to add the release/retain calls.
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