How Snow Leopard Cut ObjC Launch Time In Half

← Back to Stories (view on slashdot.org)

How Snow Leopard Cut ObjC Launch Time In Half

Posted by Soulskill on Sunday September 6, 2009 @02:33AM from the paring-down dept.

MBCook writes "Greg Parker has an excellent technical article on his blog about the changes to the dynamic linker (dyld) for Objective-C that Snow Leopard uses to cut launch time in half and cut about 1/2 MB of memory per application. 'In theory, a shared library could be different every time your program is run. In practice, you get the same version of the shared libraries almost every time you run, and so does every other process on the system. The system takes advantage of this by building the dyld shared cache. The shared cache contains a copy of many system libraries, with most of dyld's linking and loading work done in advance. Every process can then share that shared cache, saving memory and launch time.' He also has a post on the new thread-local garbage collection that Snow Leopard uses for Objective-C."

158 comments

I've heard that before.... by LO0G · 2009-09-06 02:36 · Score: -1, Troll

In other words, Apple just re-invented Superfetch
Photocopiers anyone?
1. Re:I've heard that before.... by sa666_666 · 2009-09-06 02:39 · Score: 0, Troll
  
  Also sounds like the prelink application in Linux.
2. Re:I've heard that before.... by Anonymous Coward · 2009-09-06 02:41 · Score: -1, Flamebait
  
  Isn't caching executables and shared libraries something Unix and variants have been doing for ages too? Way to stay ahead of the game, Slow Leopard :P
3. Re:I've heard that before.... by Anonymous Coward · 2009-09-06 02:43 · Score: 1, Informative
  
  Or the GAC
4. Re:I've heard that before.... by BorgDrone · 2009-09-06 02:44 · Score: 5, Informative
  
  Did you even read the article ? Suppose not... this is slashdot after all.
  The article states that prebinding (similar to prelink) was used in previous versions of OS X and has been replaced by a much faster shared cache.
5. Re:I've heard that before.... by pizzach · 2009-09-06 02:45 · Score: 0, Troll
  
  I don't think so. From the article you linked:
  
  The intent is to improve performance in situations where running an anti-virus scan or back-up utility would result in otherwise recently-used information being paged out to disk, or disposed from in-memory caches, resulting in lengthy delays when a user comes back to their computer after a period of non-use.
  Everybody obviously knows that no viruses exist for the mac so your assertions are asymptotically false.
  
  --
  Once you start despising the jerks, you become one.
6. Re:I've heard that before.... by leuk_he · 2009-09-06 02:45 · Score: 1
  
  And reintroduced dll hell as well?
7. Re:I've heard that before.... by mdwh2 · 2009-09-06 02:47 · Score: 3, Funny
  
  Well okay then, Apple were the ones who "popularised" it! ("Well I hadn't heard about Superfetch, but I heard about Apple doing it first, therefore, Apple did it first")
  Or um ... they "integrated" it better. Yeah, that's it.
8. Re:I've heard that before.... by sa666_666 · 2009-09-06 03:01 · Score: -1, Offtopic
  
  Christ, the OSX fanbois are out in force today. This is the first time I've ever gotten a troll rating, basically for stating that it's similar to something that Linux has. It wasn't meant as a disparagement. I regularly use OSX and applaud any performance improvements. But I guess we can't even mention when similar features exist on other platforms. Note that I said SIMILAR; I recognize that it isn't exactly the same as prelink in Linux.
9. Re:I've heard that before.... by bhima · 2009-09-06 03:05 · Score: 1, Informative
  
  no. we've had a variant but lesser hell for years. Which has led to a series of cargo cult like maintenance procedures for Mac OS.
  
  --
  Nothing in the world is more dangerous than sincere ignorance and conscientious stupidity.
10. Re:I've heard that before.... by CharlyFoxtrot · 2009-09-06 03:08 · Score: 3, Interesting
  
  It's nothing like Superfetch. Superfetch preloads applications into system memory and this shared cache doesn't do that instead from what I understand it preforms some of the work the linker would do on load in advance.
  
  --
  If all else fails, immortality can always be assured by spectacular error.
11. Re:I've heard that before.... by sa666_666 · 2009-09-06 03:13 · Score: -1, Offtopic
  
  And this latter part is exactly what I referred to above when I compared it to prelink in Linux. And I was subsequently marked a troll for stating this similarity.
12. Re:I've heard that before.... by pizzach · 2009-09-06 03:19 · Score: 0
  
  I hoped my ridiculous words at the end would make people laugh, but I know most slashdotters lack a sense of humor. :) Tis life.
  
  --
  Once you start despising the jerks, you become one.
13. Re:I've heard that before.... by lysergic.acid · 2009-09-06 03:22 · Score: 3, Informative
  
  Well, the FP is claiming that they're the same thing, and your post seemed to be agreeing with him. But yea, that troll rating probably should have gone to the post you replied to.
  I don't know anything about prelink, but Superfetch sounds completely different from dyld. Superfetch keeps frequently launched applications in memory to make them launch faster (much like Winamp Agent does for Winamp). dyld, OTOH, shortens application launch times by not reloading a shared library each time an application is launched. Keeping the shared library loaded in a shared cache also reduces the number of copies of that library you need loaded in memory. It doesn't sound like Superfetch does that.
  Both a turbocharger and a cold air intake can improve car performance, but that doesn't make them the same thing.
14. Re:I've heard that before.... by pizzach · 2009-09-06 03:23 · Score: 0, Troll
  
  Actually, it is interesting I was marked troll for quoting some text that the original poster linked. O.o A view into the minds of the moderators.
  
  --
  Once you start despising the jerks, you become one.
15. Re:I've heard that before.... by Simonics+Zsolt · 2009-09-06 03:32 · Score: 3, Insightful
  
  And maybe kdeinit does something similiar since 2003?
16. Re:I've heard that before.... by pizzach · 2009-09-06 03:49 · Score: 1
  
  You phrased things much better than I could fine sir. The link to the wikipedia article that the original poster included read nothing like TFA. Though because of the glaring placement of the post toward the top of the page and how straight forward it is written, I think most mods probably modded it without checking against either of the articles. That is how human nature is :). It's nice that slashdot moderation tends to correct itself over time thanks to insightful replies lower in the tree.
  
  --
  Once you start despising the jerks, you become one.
17. Re:I've heard that before.... by plsuh · 2009-09-06 03:51 · Score: 5, Informative
  Moderators, please mod the parent down -- it completely misses the point.
  Objective-C selector uniquing caching is NOT the same as Windows Superfetch.
  Objective-C uses a two-phase dispatch for method calls. When you see a call in the Objective-C source code that looks like:
  
  [myObject init];
  the dispatch system:
  
  Looks up the function pointer for the method "init" in a table.
  Calls the "init" function via the function pointer.
  The problem arises in the method dispatch table when you have multiple methods named "init" -- which is very common. When an application is loaded the dynamic loader ("dyld") needs to separately identify all of the methods named "init" (and any other methods with conflicting names) that apply to different classes. This is done by "tagging" each method in the dispatch table, a process called selector uniquing.
  Now, this has to be not only for the application binary itself, but also for any Objective-C classes in shared libraries that are loaded. Almost all apps on Mac OS X load the libobjc.dylib library, which is cached to improve performance. As a part of the caching process, Snow Leopard now does the selector uniquing only once, and then stores the uniqued selectors in the cache. Thus, any application that links against libobjc.dylib (or any other library that is in the cache) only has to unique its own selectors, not those of the library as well. This significantly reduces the amount of overhead for launching an application compared to previous versions of Mac OS X.
  This process does not attempt to retain application binary code in memory in the face of page-outs as Superfetch does. Selector uniquing caching speeds application launch times by reducing the amount of computation that has to happen at launch, not by pre-loading the application's binary.
  Thread-local garbage collection is NOT the same as Windows Superfetch.
  Thread-local garbage collection is a third phase of garbage collection added on top of the Objective-C 2.0 garbage collection system, which speeds up the garbage collection system even further. By concentrating GC to what has occurred in a single thread, the GC system can delay and reduce the cost of a slow global sweep even beyond the generational GC algorithm.
  Windows Superfetch is a response to poorly written software.
  To quote from the Wikipedia article:
  
  The intent is to improve performance in situations where running an anti-virus scan or back-up utility would result in otherwise recently-used information being paged out to disk, or disposed from in-memory caches, resulting in lengthy delays when a user comes back to their computer after a period of non-use.
  In my opinion as an experienced application developer the user should never run into the problem that Superfetch attempts to solve. Anti-malware scans or backups are generally limited by I/O transfer rates, not by CPU. In such situations, using lots of memory to pre-load data makes no sense. It is relatively easy to write a two-buffer, threaded, streaming system for situations that are constrained by disk transfer rates without consuming scads of memory.
  In the bigger picture, Superfetch attempts to learn the times of day when apps are used and pre-loads their binaries. This is a nice concept, but I have serious doubts as to how useful it really is. The penalty for guessing wrong is fairly high, and users are more tolerant of consistent small slowdowns than they are of occasional long hangs (see the Mac literature on the spinning beach ball).
  Mac OS X is less likely to need such anti-malware scans in the first place as the application binaries are now digitally signed by the developer. Any malware that attempts to insert itself into applications will run into problems. This is not to say that the Mac is immune -- I can think of a number of holes that could be exploited (such as the fact that unsigned binaries w
18. Re:I've heard that before.... by Creepy · 2009-09-06 03:52 · Score: 2, Informative
  
  For reference, normally when a program is launched without prebinding, the program has to look into the symbol table for the shared library and "bind" it (basically, tell the program where it is). Prebinding basically does that in advance and saves the lookup table, but any time the library is changed, the bindings have to be regenerated.
  The article says prebinding is actually quite efficient for C/C++ code, but objective-C (used by macOS X and iPhone) is structured more like Smalltalk or Java, and uses selectors, which I believe can't be prebound (for you java programmers, these are equivalent to interfaces - C/C++ does not have this concept and instead allows direct access to the classes using protected or public) to interface into classes and these are instanced once for every application accessing that shared library. According to TFA, by keeping a single cached copy of the selector, they avoid the memory overhead of keeping individual copies. Since the OS itself has over 30000 selectors, you can imagine this cuts overhead by quite a bit, especially with commonly loaded libraries like Cocoa.
  For people comparing this to superfetch, it's not really the same thing - superfetch was pre-loading heavily used libraries into memory to avoid the delay in loading them during start time, and this is caching the library lookups onto disk that may or may not be memory resident at any particular time.
19. Re:I've heard that before.... by malevolentjelly · 2009-09-06 04:09 · Score: 2, Informative
  
  It's nothing like Superfetch. Superfetch preloads applications into system memory [microsoft.com] and this shared cache doesn't do that instead from what I understand it preforms some of the work the linker would do on load in advance.
  The whole dyld sounds a lot like some of the basic features of the .NET runtime...
  Or maybe some of the features in this advanced futuristic os:
  http://blogs.technet.com/askperf/archive/2008/02/06/ws2008-dynamic-link-library-loader-and-address-space-load-randomization.aspx
20. Re:I've heard that before.... by Spaham · 2009-09-06 04:15 · Score: 2, Funny
  
  mod parent : should be the article itself :D
21. Re:I've heard that before.... by Anonymous Coward · 2009-09-06 04:27 · Score: 0
  
  Windows had this in 1995. The whole idea behind PE style DLLs is that you can just read in the module from disk and you can just use it as is. If the default loading address is available, which is normally almost always the case, you can use all the prebindings and you don't even have to patch your I/E tables. The only reason I won't mention the DLL cache is that that was only added in 2000 or so.
22. Re:I've heard that before.... by Anonymous Coward · 2009-09-06 04:41 · Score: 0
  
  Dude, get over it. Sometimes mods are stupid. That's life. I'm sorry someone foolishly marked you as a troll, but you really need to move on.
23. Re:I've heard that before.... by TheRaven64 · 2009-09-06 05:23 · Score: 4, Informative
  
  selectors, which I believe can't be prebound (for you java programmers, these are equivalent to interfaces - C/C++ does not have this concept and instead allows direct access to the classes using protected or public)
  I'm sorry, but this and most of the rest of your description is completely wrong. Selectors are nothing like Java interfaces. Interfaces are Java's version of Objective-C Protocols. Selectors are abstract method names (Smalltalk calls them symbols). Each Objective-C class has some data structure mapping these to function pointers. When you send a message (call a method) you look up the function pointer corresponding to the selector in the receiving class. To make this fast, all selector comparisons are done as pointer comparisons. To make this work, the runtime needs to make sure that selectors are unique. This process involves building a large hash table and inserting every selector referenced by every compilation unit into it. By making the linker handle this uniquing, you have several advantages. The first is that the resulting table can be shared more easily between processes, resulting in a memory efficiency gain. The second is that the runtime can first try doing pointer comparison when registering a new selector, and only use the hash if the linker didn't unique the selector.
  
  --
  I am TheRaven on Soylent News
24. Re:I've heard that before.... by osu-neko · 2009-09-06 06:03 · Score: 1
  
  Okay, whoever modded the above post as "Troll" is confused. Talking about the moderation system on a thread about some other topic (e.g. Snow Leopard) isn't a "Troll", it's "Off-topic".
  
  --
  "Convictions are more dangerous enemies of truth than lies."
25. Re:I've heard that before.... by ari_j · 2009-09-06 06:04 · Score: 1
  
  So, Objective-C requires selectors (such as for message names) to be interned, and the old way was to intern all selectors at process startup time when the dynamic linker does its work; but the new way is to cache the interned selectors both on disk (faster startup) and in memory (even faster startup plus saved memory overhead). Is that correct?
26. Re:I've heard that before.... by good+soldier+svejk · 2009-09-06 06:05 · Score: 1
  
  Also sounds like the prelink application in Linux.
  No, OS X has always done that. Except they call it prebinding.
  
  --
  It is cowardly, and a betrayal of whatever it means to be a Jew, to act as a white man
  
  -James Baldwin
27. Re:I've heard that before.... by Anonymous Coward · 2009-09-06 06:40 · Score: 0
  
  Do you always throw a fit when you get modded down? I'm gonna bookmark this and give you the "overrated" treatment next time I get mod points, be sure to post crying about it.
28. Re:I've heard that before.... by BESTouff · 2009-09-06 07:09 · Score: 1
  
  The intent is to improve performance in situations where running an anti-virus scan or back-up utility would result in otherwise recently-used information being paged out to disk, or disposed from in-memory caches, resulting in lengthy delays when a user comes back to their computer after a period of non-use.
  In my opinion as an experienced application developer the user should never run into the problem that Superfetch attempts to solve. Anti-malware scans or backups are generally limited by I/O transfer rates, not by CPU. In such situations, using lots of memory to pre-load data makes no sense. It is relatively easy to write a two-buffer, threaded, streaming system for situations that are constrained by disk transfer rates without consuming scads of memory.
  I don't think you understood it right: the perf problem is not for the anti-malware programs, but once they have run they have thrown everything out of the cache and subsequent applications have to re-populate it again, thus slowing eveything down. There used to be the same kind of problem under linux after the 'locate' cronjob.
29. Re:I've heard that before.... by TheRaven64 · 2009-09-06 07:14 · Score: 1
  
  Almost. The old way was to do it at module load time, in the Objective-C runtime library (libobjc), the new way is to do it in the loader (dyld). The loader caches the result of everything it does, including uniquing symbols (two symbols with the same name are resolved to one or other instance), while the runtime library does no caching.
  
  --
  I am TheRaven on Soylent News
30. Re:I've heard that before.... by Florian+Weimer · 2009-09-06 07:23 · Score: 1
  
  Thread-local garbage collection is a third phase of garbage collection added on top of the Objective-C 2.0 garbage collection system, which speeds up the garbage collection system even further. By concentrating GC to what has occurred in a single thread, the GC system can delay and reduce the cost of a slow global sweep even beyond the generational GC algorithm.
  Do you know how they detect that a pointer has escaped? Is there some sort of write barrier? How does this work with the somewhat unsafe base language?
31. Re:I've heard that before.... by guruevi · 2009-09-06 07:39 · Score: 1
  
  Dyld's (Dynamic Loader) have existed before Snow Leopard. They are extensively used in all Mac OS X versions since they are at the base of the system. They also appear in BSD and Linux under slightly different names. This just explains how they found out a way to do caching and preloading better than previously. It's like Microsoft finding out a way to automagically load all necessary dll's and correctly find out the dll amongst several different versions of the same dll for a program and preload them before the program even needs them. It does so correctly and consistently every time, they just sped it up now. I don't know if Windows DLL's even do versioning but from what I remember (latest experience was last week in XP) if one program writes over the other programs dll, you're shafted (I'm looking at you Aladdin USB/DRM Keys).
  
  --
  Custom electronics and digital signage for your business: www.evcircuits.com
32. Re:I've heard that before.... by pizzach · 2009-09-06 07:40 · Score: 0
  
  Depends on how you look at it. I was talking about how my post was rated troll which could and usually does turn into a talk about the content itself (which is on topic). A number of posts from other people on this article have been inaccurately moderated "Troll" for some reason though.
  At his point, I do believe we may be both off topic (thanks to the mods). It will be interesting to see if you get rated off topic, and this post here gets rated troll, too. Here's hoping for helpful meta-moderation.
  
  --
  Once you start despising the jerks, you become one.
33. Re:I've heard that before.... by malevolentjelly · 2009-09-06 07:44 · Score: 0
  
  I understand, and Apple did a great job with it. It just really disturbs me when Apple (and their ilk) keep rehashing work previously completed on other platforms and claiming that they somehow invented it. I am yet to see a feature that's really *new* in Snow Leopard, yet I can't stop hearing about how many amazing new technologies Apple has created.
  Apple did an intelligent new optimization of their dynamic loader on their platform. This is a good thing. They did not invent the concept of a dynamic loader.
34. Re:I've heard that before.... by TheGreenNuke · 2009-09-06 07:49 · Score: 1
  
  Sir, I believe you are mistaken. There obviously must have been at least one virus at some point for a Mac otherwise why would Apple include virus and malware protection in Snow Leopard. Only now will none exist since Apple has deemed it so by not allowing the rogue virus to infect their hardware. :P
35. Re:I've heard that before.... by v1 · 2009-09-06 10:05 · Score: 0, Offtopic
  
  Apple II had this in 1979. Back then we called it a "jump table". :)
  
  --
  I work for the Department of Redundancy Department.
36. Re:I've heard that before.... by TheRaven64 · 2009-09-06 10:15 · Score: 1
  
  There is a write barrier. Every pointer assignment is turned (by the compiler) into a call to the GC. You can find the code for this in the clang repository in lib/CodeGen/CGObjCMac.cpp (it's quite easy to read, in spite of being C++). If a pointer is assigned to a global or to an object that is marked as belonging to another thread, then it is treated as having escaped. The same is true if you call CFRetain() on it (which increments the ref count and tells the GC not to free it until the CFRelease() has been called.
  
  --
  I am TheRaven on Soylent News
37. Re:I've heard that before.... by Green+Monkey · 2009-09-06 10:56 · Score: 2, Insightful
  
  Gretchen, stop trying to make Superfetch happen. It's not going to happen.
  
  --
  Green Monkey
38. Re:I've heard that before.... by gutter · 2009-09-06 11:39 · Score: 1
  
  Dude, I think you're hearing things that people aren't saying. The article describes how apple has improved their dynamic loading. The author doesn't claim they invented it. Apple doesn't claim they invented it. Nobody said anything about amazing new technologies Apple created.
  
  --
  Check out DRM-free movies at http://www.bside.com
39. Re:I've heard that before.... by bonch · 2009-09-06 15:26 · Score: 0
  
  What the fuck? Nobody claimed Apple invented a dynamic loader. Nobody said this was a new technology. It's just a technical article about how Apple improved app launch time in Snow Leopard.
40. Re:I've heard that before.... by shmlco · 2009-09-06 19:08 · Score: 1
  
  Applesoft BASIC on the Apple II mapped keyword tokens directly to a jump table of ROM entry points.
  Other than the fact that it was not object-based, didn't reference system or external libraries, and all of the token offsets were fixed and predetermined...
  It's exactly the same. :)
  
  --
  Any sect, cult, or religion will legislate its creed into law if it acquires the political power to do so.
41. Re:I've heard that before.... by Anonymous Coward · 2009-09-06 22:30 · Score: 0
  
  The intent is to improve performance in situations where running an anti-virus scan or back-up utility would result in otherwise recently-used information being paged out to disk, or disposed from in-memory caches, resulting in lengthy delays when a user comes back to their computer after a period of non-use.
  In my opinion as an experienced application developer the user should never run into the problem that Superfetch attempts to solve. Anti-malware scans or backups are generally limited by I/O transfer rates, not by CPU. In such situations, using lots of memory to pre-load data makes no sense. It is relatively easy to write a two-buffer, threaded, streaming system for situations that are constrained by disk transfer rates without consuming scads of memory.
  This part right here makes no sense.
42. Re:I've heard that before.... by Anonymous Coward · 2009-09-07 00:47 · Score: 0
  
  Small talk????
  Obj-C is a union of smalltalk and C.
  Just my 5 sents even if i have no clue.
43. Re:I've heard that before.... by plsuh · 2009-09-07 02:12 · Score: 0
  The intent is to improve performance in situations where running an anti-virus scan or back-up utility would result in otherwise recently-used information being paged out to disk, or disposed from in-memory caches, resulting in lengthy delays when a user comes back to their computer after a period of non-use.
  In my opinion as an experienced application developer the user should never run into the problem that Superfetch attempts to solve. Anti-malware scans or backups are generally limited by I/O transfer rates, not by CPU. In such situations, using lots of memory to pre-load data makes no sense. It is relatively easy to write a two-buffer, threaded, streaming system for situations that are constrained by disk transfer rates without consuming scads of memory.
  I don't think you understood it right: the perf problem is not for the anti-malware programs, but once they have run they have thrown everything out of the cache and subsequent applications have to re-populate it again, thus slowing eveything down. There used to be the same kind of problem under linux after the 'locate' cronjob.
  In these situations it's usually not the disk cache that's the problem, it's what binaries the OS has loaded in RAM. If app A is inactive and app B requests a lot of memory, the OS will swap app A's binary out to the VM backing store. When app A becomes active again there is a delay while its code is reloaded from the VM backing store. There is no reason for an app such as an A/V program or backup program or locate (all of which are I/O-bounded) to require huge amounts of memory other than the developer not realizing how to scale to handling large volumes of data.
  What's happening is that the A/V app is just loading the entire application that it wants to scan into memory, then scanning it. This is unnecessary, especially if the app is really big and has lots of non-code resources (e.g., graphics). It's easy for the programmer, but bad for performance; indeed, it may cause problems for A/V performance as well if the app binary is larger than the amount of available memory, causing the A/V program to thrash in the VM system directly. Instead, create two buffers (each one around 1 MB as a good starting point, tune according to available memory, disk transfer rates, and system loads) and two threads. Thread 1 loads the buffers from disk -- its conditions are:
  Check buffer X -- if X is empty, load it from the disk and mark it as full. If X is full, go to step 2.
  Check buffer Y -- if Y is empty, load it from the disk and mark it as full. If Y is full, go to step 1.
  Thread 2 does the actual A/V scans:
  Check buffer X -- if X is full, scan it and mark it as empty. If X is empty, go to step 2.
  Check buffer Y -- if Y is full, scan it and mark it as empty. If Y is empty, go to step 1.
  You can do more improve efficiency by more threads, blocking on semaphores, and waiting on locks, but you get the idea. Note that there is no point in more than two buffers, since Thread 2 will always be done long before Thread 1. If the malware scan requires comparing widely separated parts of the target binary you may need to cache portions of it, but there's still no reason to hold in RAM the vast majority of the target binary.
  --Paul
44. Re:I've heard that before.... by Jimithing+DMB · 2009-09-07 04:38 · Score: 2, Informative
  
  selectors, which I believe can't be prebound (for you java programmers, these are equivalent to interfaces - C/C++ does not have this concept and instead allows direct access to the classes using protected or public)
  I'm sorry, but this and most of the rest of your description is completely wrong. Selectors are nothing like Java interfaces. Interfaces are Java's version of Objective-C Protocols. Selectors are abstract method names (Smalltalk calls them symbols). Each Objective-C class has some data structure mapping these to function pointers.
  Although I will agree with you that GPP is somewhat misinformed I take issue with your statement that selectors are nothing like Java Interfaces.
  It is true that the class structure of Objective-C (one root NSObject class, at least in common practice) and the class structure of Java (one root Object class) are virtually identical. And it is true that an Objective-C protocol has feature parity with a Java Interface and when you think of formal interfaces in Java the equivalent to that in Objective-C is a protocol.
  So Java has anObj instanceof SomeClass which will indicate that anObj is an instance of SomeClass or an instance of some other class that derives from SomeClass. The Objective-C equivalent to this is [anObj isKindOfClass:[SomeClass class]]. And Java has anObj instanceof SomeInterface where the equivalent in Objective-C is [anObj conformsToProtocol:@protocol(SomeInterface)].
  But then Objective-C also has this nifty thing [anObj respondsToSelector:@selector(doSomething:)] which does exactly what it says and allows you to see if the object will respond to the doSomething selector that takes one argument. Java has no analogue to this. I mean, you can sort of fake it using reflection to find methods but it isn't quite the same thing.
  The bottom line is that when a unique selector can be looked up like this each selector functions almost as if it were its own Java-style interface. There is clearly a parallel between Java if(anObj instanceof DoSomethingInterface) ((DoSomethingInterface)anObj).doSometing(1); and Objective-C if([anObj respondsToSelector:@selector(doSomething:)]) [(id)anObj doSomething: 1];
  From a coding standpoint where I would think to use a respondsToSelector: in Objective-C I wind up making an interface containing exactly 1 method in Java. Sometimes it's the right choice to add the extra lines and make an interface (and if so, then you should add all the extra lines and make a protocol in Objective-C). But often times I find the required formality of Java to be a distraction.
45. Re:I've heard that before.... by ari_j · 2009-09-07 04:47 · Score: 1
  
  For thoroughness, would you mind defining 'module load time' in the Objective-C context for me? I am familiar with the language but much less familiar with its runtime support components.
46. Re:I've heard that before.... by TheRaven64 · 2009-09-07 06:38 · Score: 1
  
  When you compile any C-family language, you get an object code file. This contains symbols which will be resolved by either the static or dynamic linker and various sections. One of these sections contains an array of pointers to functions which are called by the loader when that object file is loaded. These are not used in C. In C++, they are used for static constructors. In Objective-C, there is one that issues a call to __objc_exec() with a pointer to the struct objc_module created for that compilation unit as the argument. This registers all of the selectors, protocols, classes, and categories declared in that compilation unit with the module.
  When you statically link object code files together, these sections will be concatenated. When you then load the resulting object code file (either an executable or a binary), the loader will iterate through the combined section and call each function in turn. This is how you get code executing before main() in a program.
  
  --
  I am TheRaven on Soylent News
47. Re:I've heard that before.... by ari_j · 2009-09-07 12:21 · Score: 1
  
  Thanks. The part about Objective-C using that mechanism to register, on a per-compilation-unit basis, selectors, classes, and the like is news to me. :)
48. Re:I've heard that before.... by mini+me · 2009-09-08 17:55 · Score: 1
  
  From a coding standpoint where I would think to use a respondsToSelector: in Objective-C I wind up making an interface containing exactly 1 method in Java.
  With Objective-C, a method may not even exist at compile time. It is impossible to define formal interfaces in many cases. respondsToSelector allows you to ensure that any arbitrary object walks, swims, and quacks like a duck without strict class definitions.
49. Re:I've heard that before.... by Anonymous Coward · 2009-09-09 13:14 · Score: 0
  
  ...an array of pointers to functions which are called by the loader when that object file is loaded...In C++, they are used for static constructors.
  There are no static constructors in C++. Your other posts indicate that you're well-informed, so I assume you wrote that as shorthand for objects declared at namespace scope and static data members, but readers unfamiliar with C++ might have gone away misinformed. Also, IIRC nothing in the C++ standard requires static initialization to be handled by the loader (some platforms may not even have anything identifiable as a "loader"), but maybe you were referring only to Mac C++ implementations (I have no experience there).
  
  - T
enough fucking by Anonymous Coward · 2009-09-06 02:37 · Score: 0, Troll

snow leopard stories!
1. Re:enough fucking by Anonymous Coward · 2009-09-06 02:44 · Score: 5, Funny
  
  You've had enough of fucking, and would like more Snow Leopard stories? Each to his own, I guess.
2. Re:enough fucking by lysergic.acid · 2009-09-06 02:50 · Score: 4, Funny
  But I haven't even had a chance to submit these yet:
  
  Snow Leopard in Afghanistan
  Snow Leopard Diary
  LEOPARD PICTURES: Rare Snow Cats Caught by Camera Traps
  Terich Valley: Snow Leopard Survival Issues
  Central Park Zoo visitors go wild for new snow leopards
3. Re:enough fucking by mdwh2 · 2009-09-06 02:51 · Score: 1, Funny
  
  Hey, it makes a refreshing change from the daily "Do XYZ On Your Iphone" stories! I'm love the variation today here on Apple- er Slashdot.
4. Re:enough fucking by NoYob · 2009-09-06 02:55 · Score: 0, Troll
  
  What?!?
  Don't you understand that Snow Leopard is God's gift to operating systems?
  Objective-C happens to be the greatest programming language EVAR!
  Folks accuse Apple of re-inventing Superfetch. That is non-sense. Everything that Apple does is new and unique! It only seams as if Apple copies stuff because others come out with their own versions so fast that it sometimes seams as though they invented it first. But we all know that it was Apple who invented it first because their the ones who drive innovation in the PC world!
  Anyway, this story came out just in time! I'm on my way to Sunday Apple services at the local Apple store. The pastor was blessed by Jobs himself once at a MacWorld show! To be touched by a hand that was once touched by His Appleness is just spiritually uplifting!
  Praise Jobs - Glory Hallowed Be - Aaaaaaaaaamayyyen - Yaaaaeeeeeees!
  
  --
  It's NOT me! It's the meds! I'm on 1000mg of Fukitol.
5. Re:enough fucking by 644bd346996 · 2009-09-06 02:56 · Score: 2, Insightful
  
  Considering that the whole point of Snow Leopard was to refine the internal structure of the operating system and introduce new features for developers, it should come as no surprise that there are far more /. appropriate stories about it than the more eye-candy oriented releases.
6. Re:enough fucking by shovas · 2009-09-06 03:05 · Score: 1
  
  Maybe I've never realized before how bad slashdot is at beating a dead horse. But, really, this is going overboard with apple stories of the least bit of consequence or relevance (barring this story for once). I'm starting to think slashdot doesn't have pre-arranged deals with apple, and others, but that they get paid if a submission does happen to come through and is approved.
  
  --
  Selah.ca. Pause, and calmly think on that.
7. Re:enough fucking by TheRaven64 · 2009-09-06 04:21 · Score: 4, Insightful
  
  Comparing this to Superfetch is ignorant beyond belief. Superfetch is part of the paging system on Windows and attempts to trigger page faults before the data is actually needed so that it's already cached when it is needed. This is quite a nice feature and one I am naturally prejudiced to like because my PhD was in this topic.
  This is entirely different. Part of it is similar to the existing prebinding / prelinking stuff in Leopard / Linux, which generates the relocation tables in position-independent code. This is nothing like anything in Windows, because Windows doesn't use position-independent code for shared libraries (it uses a horribly ugly hack which performs better in the best case and much worse in the worst case). The article is a bit too light on details to understand exactly why the new version performs so much better.
  The other half, however, is very clever. By caching the selector uniquing information, they are saving a lot of time when loading compilation units containing Objective-C code. Even better is the fact that, because these symbols are now not modified, they can be shared between processes without triggering copy-on-write faults. This isn't actually that hard to implement for the GNU runtime; just give the selector symbols mangled names and mark them as having common linkage (it's a bit harder on Darwin because Mach-O is weird), then you can use pointer comparison as a first step in the runtime and avoid the strcmp() call. Combining this with the prelinking support and you get the caching for free, which is very nice. I actually implemented this in Clang while writing this post, so expect to see it on non-Apple platforms soon too.
  
  --
  I am TheRaven on Soylent News
8. Re:enough fucking by Anonymous Coward · 2009-09-06 04:50 · Score: 0
  
  Rather it strikes me that there are too few snow leopard stories. The gadget press goes crazy for almost every Apple launch, but somehow this OS is low key. Gizmodo isn't writing 100 posts a day about every nook and cranny of it, so on and so forth. A hypothetical tablet whereas seems to get a mention even in the new york times on a weekly basis. I simply don't get it.
  Maybe it's due to the fact that this new version does not add shiny bells and whistles to a crumbling architecture. Rather it focuses on bringing some seriously good ideas together under one roof. That, to me, is a new standard compared to the mindless hype over pretty graphics.
  Oh then again maybe the said "journalists" don't understand what they are seeing. Usually the core Apple fanatics orgasm by this time. Weird. Maybe the abscence of a RDF during launch had something to do with it.
  What do you guys think about it?
  If I ever switch from dual booting Ubuntu (buggy flash and video editing support will probably make me do it) and Win XP(for those windows only apps). OS X snow leopard is the thing I would buy.
9. Re:enough fucking by Anonymous Coward · 2009-09-06 06:14 · Score: 0
  
  No, this would be an decent enough story, assuming Slashdot actually was "news for nerds" and people were interested in the technical underpinnings. The handful of decent comments generated show that.
  However, in reality, Slashdot is a gloryhole of non-technical luser fanboys who just want to piss on each other about who ripped off whom without understanding any of the details.
10. Re:enough fucking by igny · 2009-09-06 07:23 · Score: 2, Funny
  
  Apple's dyld comes in handy in both cases.
  
  --
  In theory there is no difference between theory and practice. In practice there is. - Yogi Berra
11. Re:enough fucking by man_of_mr_e · 2009-09-06 07:26 · Score: 1
  
  Sounds like this "solution" is only a benefit because Apple chose to standardize on a language that generates very slow executables by default. Thus, the problem (and solution) are of their own making.
  
  --
  If you need web hosting, you could do worse than here
12. Re:enough fucking by hamburger+lady · 2009-09-06 07:48 · Score: 2, Funny
  
  that sound you hear is NoYob's spirit being completely crushed.
  bravo, sir.
  
  --
  
  ---
  Is this the MPAA? Is this the RIAA? Is this the DMCA? I thought it was the USA!
13. Re:enough fucking by Anonymous Coward · 2009-09-06 08:06 · Score: 0
  
  You are correct that this is nothing like Superfetch; however...
  This is nothing like anything in Windows, because Windows doesn't use position-independent code for shared libraries (it uses a horribly ugly hack which performs better in the best case and much worse in the worst case).
  Shows you have no idea what you are talking about with regard to Windows.
  Your reply is a basic reciting of a couple of Wikipedia articles and you are not smart enough to realize that the 'hacks' the Wikipedia article that you are referencing is in regard to outdated DLL sharing technologies from Windows.
  The article and your position is correct if you are stuck in Win32 and in the pre-Win2k/XP era of computing.
  1) WIndows is NOT just WIn32, running the BSD subsystem on Vista, do you not have the exact same BSD form of linking and execution? So your blanket statement about Windows fails here, as BSD on NT is BSD on Windows, get it?
  2) Windows XP changed how DLL sharing worked in the Win32 subsystem, and Vista and Win7 made massive changes to the DLL sharing mechanisms, as they are no longer fixed-position addressing.
  3) You either don't realize there are several shared DLL/Asset technologies in Windows or you are just ignorning them. Here is a hint, take a look at something called .NET or even go further to core NT linking technologies
  4) The way NT is designed, the core OS is not locked to any code execution or linking constructs, especially not something from an aged version of the Win32 subsystem. (This is one reason the VMS and UNIX designers of NT, chose not to use traditional kernel or UNIX constructs that are limited.)
  *I use Win32 loosely, as there are technically two main NT OS subsystems, Win32 and Win64, with a legacy Win16 subsystem on the 32bit version of Vista/Win7.
  You can beat up MS and Windows all you want, but if you want to pick on code linking, asset sharing, code caching or fundamental execution and compiler technologies, Microsoft is still one of the best companies in the world and continue to define technology progression in areas most SlashDot reader don't even realize exists.
  Pull-Quoting a Wikipedia article doesn't help your position, especially if you do have a PhD in this area.
  PS You might want to mention your actual doctorate, as the last time I was teaching there was no such thing as a doctorate on library sharing technology.
14. Re:enough fucking by Jesus_666 · 2009-09-06 08:44 · Score: 2, Informative
  
  You are reading apple.slashdot.org. It might have occurred to you that at this subdomain you might find stories about Apple? You can filter it out, you know.
  
  --
  USE HOT GRITS WITH STATUE OF NATALIE PORTMAN (NAKED AND PETRIFIED)
15. Re:enough fucking by Hurricane78 · 2009-09-06 08:58 · Score: 1
  
  I still don't see what the point is. My solution to this: More RAM and *Autostart*. Really. I start everything I need at boot time. Which is quite rare. So I never felt the need to speed up the first start of any programs.
  
  --
  Any sufficiently advanced intelligence is indistinguishable from stupidity.
16. Re:enough fucking by PhunkySchtuff · 2009-09-06 09:58 · Score: 1
  
  Yes, wouldn't it be terrible if Apple actually fixed issues with their OS...
  
  --
  Specialist Mac support for creative pros, Melbourne
17. Re:enough fucking by Anonymous Coward · 2009-09-07 04:18 · Score: 0
  
  I don't think Pull Quote means what you think it means.
I thought this was the shared libs always worked by noidentity · 2009-09-06 02:43 · Score: 3, Interesting

I thought one of the points of shared libraries was that the files could simply be mapped read-only into the memory of each process and executed directly. This would only require one physical copy in memory, even though it may exist at multiple logical addresses.
I take it since then shared library machine code has had to be patched in memory after it's loaded for a while now, thus preventing easy sharing among processes, and causing the page to need its own space in the swap file.
Sounds like this latest improvement effectively brings things back to the way they were, by effectively writing this patched version back to disk so that it can be mapped read-only as before, and not have to be patched every time the library is loaded into a process. It's odd, because I thought the OS already did this several versions ago when prebinding.
dyld by DoofusOfDeath · 2009-09-06 03:04 · Score: 5, Funny

dyld - noun. A reminder that regardless of age, you'll always have an adolescent sense of humor.
1. Re:dyld by Anonymous Coward · 2009-09-06 03:09 · Score: 0
  
  Oh...
2. Re:dyld by DoofusOfDeath · 2009-09-06 03:10 · Score: 0
  
  Oh...
  That's what she said.
3. Re:dyld by Anonymous Coward · 2009-09-06 11:48 · Score: 0
  
  dyld-oh I get it...
  Sorry.
4. Re:dyld by Anonymous Coward · 2009-09-06 14:32 · Score: 0
  
  i don't ge tit
Doesn't sound like this is loading apps. by Shag · 2009-09-06 03:11 · Score: 2, Interesting

Sounds like they've just updated their dynamic (shared) library loader to be able to handle Objective C (aka Cocoa) instead of just plain C, and to be a little smarter about keeping track of what it's already got going on, so it doesn't duplicate things.
As a long-time UNIX and Linux (and other more esoteric OSes) geek, this alone doesn't impress me too much. The idea that they went through the whole OS and worked to get little efficiency/performance gains like this all over the place impresses me a little more.

--
Village idiot in some extremely smart villages.
1. Re:Doesn't sound like this is loading apps. by Ma8thew · 2009-09-06 03:24 · Score: 4, Informative
  
  Objective-C is not equivalent to Cocoa. Cocoa is a set of frameworks written in Obj-C and primarily used by Obj-C programs.
2. Re:Doesn't sound like this is loading apps. by Shag · 2009-09-06 03:48 · Score: 1
  
  Good point. I should have said "as used in Cocoa" or something to be clearer. I'm not sure whether there are people out there writing Objective-C apps for the Mac without Cocoa, though. I guess there's always someone who won't use the nifty library and shortcuts and all that, because they're hardcore, efficiency nuts, or just masochists...
  
  --
  Village idiot in some extremely smart villages.
3. Re:Doesn't sound like this is loading apps. by INT_QRK · 2009-09-06 04:33 · Score: 3, Interesting
  
  What impresses me significantly is that instead of concentrating on glitzy and often useless new "features," Apple actually implemented substantive performance enhancements. The import of this approach can't be praised enough in my view. Anecdotally, I recovered 6 GB of hard drive space, and immediately experienced noticeably zippier launches since yesterday's upgrade. My MacBook Air on Snow Leopard loaded on feels almost as nimble as my old IBM T-41 that operates on Ubuntu 9.04. Holy cow, this is no small thing. Just, good on them!
4. Re:Doesn't sound like this is loading apps. by Anonymous Coward · 2009-09-07 12:26 · Score: 0
  
  What impresses me significantly is that instead of concentrating on glitzy and often useless new "features," Apple actually implemented substantive performance enhancements.
  You're spreading FUD; Apple is behind a lot of technological advancement from hardware to protocols to compiler technology.
This is news... how? by Foredecker · 2009-09-06 03:14 · Score: -1, Troll

So, Snow Leopard is now doing something Windows has always done... how is this news?

--
Jibe!
Sex wi*th a DOLL by Anonymous Coward · 2009-09-06 03:14 · Score: -1, Offtopic

a sad world. at
Is this really something new? by Anonymous Coward · 2009-09-06 03:14 · Score: 0

What's the difference between this and sticky files?
1. Re:Is this really something new? by AndGodSed · 2009-09-06 03:25 · Score: 2, Funny
  
  erm... these don't stick?
  
  --
  Seven Days with Ubuntu Unity
2. Re:Is this really something new? by K.+S.+Kyosuke · 2009-09-06 07:53 · Score: 1
  
  erm... these don't stick?
  Not even sticky files stick when applied to glue languages like Python. Must be glue incompatibility or something.
  
  --
  Ezekiel 23:20
Commen Sense Sharded Library by hackus · 2009-09-06 03:28 · Score: 0, Troll

I do not wish to be a poo poo, but since dynamic libraries and shared libraries have been around for just about forever, when even a second year CS major would immediately notice this could be done, is such big news now?
The first thing I would have done is built a cache for the library system. LINUX has one, why not the Mac?
So certainly I congratulate the Mac community. But wow, DUH, a cache for the linkage editor. :-)
-Hack

--
Got Geometrodynamics? Awe, too hard to figure out? Too bad.
1. Re:Commen Sense Sharded Library by Anonymous Coward · 2009-09-06 03:47 · Score: 3, Interesting
  
  Me thinks you (and many other readers) are mistaking this feature for more traditional static dyld caching.
  This enhancement is actually about caching a runtime computation for Objective-C purposes. In practice, as the linked article indicates, this computation is consistent most of the time. In some cases it is not. So to handle the general and most common case, these computations (selector uniquing) are cached and used across different processes.
  So the fair question is does Linux cache selector-uniquing?
2. Re:Commen Sense Sharded Library by keean · 2009-09-06 04:08 · Score: 1
  
  Does Linux need selector uniquing if it doesn't use Objective-C? To me this sounds like an inefficiency in Objective-C that made it less efficient than C++ (the other OO flavour of C) has been improved somewhat.
3. Re:Commen Sense Sharded Library by Anonymous Coward · 2009-09-06 04:12 · Score: 0
  
  "Less efficient than C++" is a pretty pointless thing to say. They're different languages with different capabilities. It makes no more sense to say that one is more efficient than the other than it does to say a tree is more efficient than a cat.
4. Re:Commen Sense Sharded Library by lurch_mojoff · 2009-09-06 04:44 · Score: 3, Insightful
  
  Does Linux need selector uniquing if it doesn't use Objective-C?
  No it doesn't. Since the average executable on linux is static code linked to dynamic libraries made up of static code, you get your "selector uniquing" at compile time - you don't get a method selector description, instead you get a pre-calculated and already unique address of the method or function.
  
  To me this sounds like an inefficiency in Objective-C that made it less efficient than C++ (the other OO flavour of C) has been improved somewhat.
  It is a tradeoff. You get to worry about the performance of shared library selector uniquing, but you get all the benefits of dynamic language and runtime. In practice such inefficiencies matter most in cases where you are very constrained for resources - e.g. on a phone, as hinted in TFA. I doubt in the context of the rest of the performance and efficiency improvements in Snow Leopard and on a reasonably modern computer, the 1/10 of a second or the few megabytes of memory saved matter all that much.
5. Re:Commen Sense Sharded Library by Anonymous Coward · 2009-09-06 04:44 · Score: 0
  
  I don't think we'll get very far comparing an Objective-C (or Objective-C++) app against a C++ app. For better or worse, Apple has chosen to use Objective-C for Cocoa (GUI applications) and is simply making performance improvements for it.
6. Re:Commen Sense Sharded Library by keean · 2009-09-06 04:58 · Score: 1
  
  Makes sense... but I am not sold on the benefits of a dynamic language... how is this better than dynamically loaded shared libraries? If you really need a dynamic framework there is always XPCOM, which gives you the added benefit of being able to use it from many different languages, and of course the dynamic binding is built into Javascript which makes it ideal for linking together components written in C++.
7. Re:Commen Sense Sharded Library by foniksonik · 2009-09-06 08:35 · Score: 1
  
  The article on Arstechnica about Snow Leopard goes into some detail about the advantages of Obj-C being a dynamic language... primarily due to the new inclusion of Closures aka functions assigned to variables so that you can pass a function to another function with dynamic arguments.
  This makes for not necessarily a better performing language but an easier, more efficient and less buggy language.
  It's still likely a personal coding preference of course.
  
  --
  A fool throws a stone into a well and a thousand sages can not remove it.
8. Re:Commen Sense Sharded Library by Anonymous Coward · 2009-09-06 09:07 · Score: 0
  
  The article on Arstechnica about Snow Leopard goes into some detail about the advantages of Obj-C being a dynamic language... primarily due to the new inclusion of Closures aka functions assigned to variables so that you can pass a function to another function with dynamic arguments.
  Closures exist in several static languages too.
9. Re:Commen Sense Sharded Library by Anonymous Coward · 2009-09-06 09:49 · Score: 0
  
  The fact that Apple's "blocks" (what they call closures/anonymous functions/etc.) are available in C/C++ should make it pretty damned obvious that they are completely unrelated to the advantages of using a dynamic language.
  There are plenty of advantages to using a dynamic language, but blocks ain't one of them.
10. Re:Commen Sense Sharded Library by bonch · 2009-09-06 15:32 · Score: -1, Flamebait
  
  Okay, it's time to bring out the fucking guns.
  Jesus fucking christ, you goddamn idiots. Read the fucking article. This is about selector caching for Objective-C. Your fucking piece of shit Linux doesn't do that, you yogurt-eating, functionally brain-dead simpleton. Please douse yourself in gasoline, jump off a building, and ignite yourself so that you explode onto the crowd below, raining guts and vital organs like a grotesque storm of stupidity.
  FUCKING HELL. RAWR.
11. Re:Commen Sense Sharded Library by Anonymous Coward · 2009-09-07 00:58 · Score: 0
  
  Linux users might want to ty GNU Step
12. Re:Commen Sense Sharded Library by abhi_beckert · 2009-09-07 01:04 · Score: 1
  
  Comparing JavaScript to Objective-C is a big leap. They're completely different.
  Yes, they're both "dynamic". But:
  * JavaScript is not a "proper" object oriented language, Objective-C is.
  * JavaScript is a lot more dynamic than Objective-C, it's compiled at run time. Objective-C just does some decisions at runtime.
  * Objective-C is orders of magnitude faster than JavaScript (I don't actually know how much faster, but having programmed in both I'm confident a few test would reveal tasks that take 2 seconds in javascript would take less than a millisecond in Objective-C)
  * Objective-C is compiled by a *C* compiler (more often than not, a C++ compiler). This means that any C/C++ code you find on the 'net, or any C/C++ library you find on the net, can be accessed seamlessly within your Objective-C code.
  * Because you can mix C/C++ code into your Objective C code, you can use the language which bests suites your task, for example a function could start with 3 lines of Objective-C code, then have 20 lines of C++, and then 4 more lines of Objective-C.
  As for not being convinced of dynamic languages... it really does depend on the task at hand. But it is generally accepted (definitely by me) that software written in a dynamic language tends to be less buggy (buffer over-runs and memory leaks are virtually impossible in many dynamic languages for example) and faster to write. Where you draw the line between bugs/faster to write and performance/flexibility depends on the individual project.
13. Re:Commen Sense Sharded Library by Anonymous Coward · 2009-09-07 01:40 · Score: 0
  
  JavaScript is not a "proper" object oriented language, Objective-C is.
  
  You obviously don't know what you're talking about. JavaScript is 100% pure OO. Objective C, thanks to the need for legacy C compatibility, isn't even close.
14. Re:Commen Sense Sharded Library by keean · 2009-09-07 02:30 · Score: 1
  
  I was referring to XPCOM, which allows many languages (including C++) to have the same kind of dynamic binding as objective-c. It is used by firefox to implement plugins for example. Of course in C++ it looks messy as the management of XPCOM objects is exposed. In Javascript this management is hidden. There is nothing wrong with implementing the computationally heavy parts of an application in C++, and then using Javascript as the toplevel. Besides, Javascript is a proper object oriented language. Javascript is both object oriented (using the object prototype model) and supports closures (something neither C, C++, and objective C cannot manage). See: http://javascript.crockford.com/javascript.html
15. Re:Commen Sense Sharded Library by Anonymous Coward · 2009-09-07 08:59 · Score: 0
  
  C, C++, and Objective-C all support closures on the Mac platform now, as of Mac OS X 10.6. Whether this will filter out to other platforms or whether it will remain an Apple-specific extension remains to be seen, but if you're writing Mac-only code then you can have closures in your C now.
Too bad I had to restore my computer to Leopard... by Anonymous Coward · 2009-09-06 03:29 · Score: -1, Offtopic

Too bad I had to restore my computer to Leopard.....because with all this whiz-bang technology, many of my applications started to crash when saving files. I lost a days time updating and then restoring my two macs.
Re:I thought this was the shared libs always worke by Anonymous Coward · 2009-09-06 03:29 · Score: 2, Informative

The shared libs are shared. What was not shared before is the linking table, that must be built for accessing that shared code. prelink precalculates that table, and this apple thing does more or less the same.
GNUstep Is Not Cocoa by tepples · 2009-09-06 04:04 · Score: 1

I'm not sure whether there are people out there writing Objective-C apps for the Mac without Cocoa, though. I guess there's always someone who won't use the nifty library and shortcuts and all that, because they're hardcore, efficiency nuts, or just masochists...
Or they use only a subset of Cocoa because they plan to port the app to GNU/Linux, *BSD, and Windows using GNUstep, an OpenStep-compatible toolkit that implements only some of Cocoa.
1. Re:GNUstep Is Not Cocoa by Shag · 2009-09-06 07:34 · Score: 1
  
  GNUstep FTW indeed! And thanks, because I think you've just come up with an answer to something I was pondering the other day - what Adobe will do for Creative Suite 5, since they want to go 64-bit on the Mac, and that can't be done using the transitional Carbon library.
  They're going to have to totally rewrite it in Cocoa (which I think is frankly a good thing, since the current codebase probably dates back to the early-to-mid 1990s, and has just had more and more crap glued onto it over the years), but I was thinking it'd be an awful pain to maintain both a Cocoa codebase for the Mac and the plain old codebase for Windows.
  If they can do an Objective-C codebase, and keep the differences between the code for Mac (using Cocoa everything) and the code for Windows (using GNUstep) to a reasonably low level, they can still have a single codebase, which would make life easier going forward. (Plus, it'd be a modern OO codebase.)
  
  --
  Village idiot in some extremely smart villages.
2. Re:GNUstep Is Not Cocoa by Jesus_666 · 2009-09-06 08:46 · Score: 1
  
  Nah, they'll probably write a wrapper that glues their C++/Carbon code to Cocoa and blame Apple for CS5 being slow.
  
  --
  USE HOT GRITS WITH STATUE OF NATALIE PORTMAN (NAKED AND PETRIFIED)
3. Re:GNUstep Is Not Cocoa by cheesybagel · 2009-09-09 07:55 · Score: 1
  
  Or use Qt.
4. Re:GNUstep Is Not Cocoa by Jesus_666 · 2009-09-09 08:56 · Score: 1
  
  You mean Adobe would not use horribly outdated APIs for no reason other than their unwillingness to accept that Mac OS 9 is dead? What's next, Microsoft implementing Windows 8 around the Linux kernel?
  
  --
  USE HOT GRITS WITH STATUE OF NATALIE PORTMAN (NAKED AND PETRIFIED)
dÃ©jÃ vu by Anonymous Coward · 2009-09-06 04:21 · Score: 0

SGI did this linking trick in the early '90s - they called it Quickstart.
Start working at 9 AM by tepples · 2009-09-06 04:23 · Score: 1
Objective-C uses a two-phase dispatch for method calls. When you see a call in the Objective-C source code that looks like:

[myObject init];
the dispatch system:
1. Looks up the function pointer for the method "init" in a table.
2. Calls the "init" function via the function pointer.
C++ follows the same steps. The big difference is that in Objective-C, the dispatch table is an associative array (C++ unordered_map, Java HashMap, Python dict) from strings to function pointers, not a plain array (C++ vector, Java ArrayList, Python list).

In my opinion as an experienced application developer the user should never run into the problem that Superfetch attempts to solve. Anti-malware scans or backups are generally limited by I/O transfer rates, not by CPU. In such situations, using lots of memory to pre-load data makes no sense. It is relatively easy to write a two-buffer, threaded, streaming system for situations that are constrained by disk transfer rates without consuming scads of memory.
But then you rely on the operating system to provide a method for applications to provide cache hints, and you rely on the antivirus software to provide such hints. SuperFetch tries to infer these even for applications developed prior to widespread knowledge of these hints or ported from systems that lack these hints.

In the bigger picture, Superfetch attempts to learn the times of day when apps are used and pre-loads their binaries. This is a nice concept, but I have serious doubts as to how useful it really is.
Having my applications ready to start at 08:57 when I'm about to grab the mouse at 08:58 improves my productivity. Consider that employees have sued their employers for requiring that employees be present during application startup time but not paid until the application has fully started up.

Mac OS X is less likely to need such anti-malware scans in the first place as the application binaries are now digitally signed by the developer.
But who signs the developer's certificate? And what keeps malware publishers from signing their trojans?

Any malware that attempts to insert itself into applications will run into problems.
Unless an application tries to insert itself as, say, an assistive technology using the accessibility API.
1. Re:Start working at 9 AM by larry+bagina · 2009-09-06 05:11 · Score: 1
  
  c++ virtual functions go through the vtable (with an offset known at compile time). With Objective C, the selector/function pointer might not be in the associative array, so all the methods (stored as a linked list of arrays) need to be scanned (and inserted into the associative array if found) And if it's still not found, you send another message asking if it can respond, at which time it may add a new method on the fly.
  
  --
  Do you even lift?
  These aren't the 'roids you're looking for.
2. Re:Start working at 9 AM by TheRaven64 · 2009-09-06 05:29 · Score: 1
  This depends on the implementation. What you say is almost true for the Apple runtime, which has a small cache and then does a slow search along a list of arrays for cache misses. The GNU runtime uses a tree for dispatch, which is slower than Apple's cache (although not by much) and a lot faster in cases of a cache miss (by a lot). In 10.6 there are actually three fall-back methods if the selector is not found:
  
  If it's a fast proxy, then the object can provide a new receiver and the process starts again.
  
  The object can use the runtime functions to install a method, and then the process begins again.
  
  The message is wrapped up in an NSInvocation object and passed to the object to handle (forward over the network, or whatever).
  --
  I am TheRaven on Soylent News
3. Re:Start working at 9 AM by rekoil · 2009-09-06 07:16 · Score: 1
  
  But who signs the developer's certificate? And what keeps malware publishers from signing their trojans??
  IIRC the intent here is that any change in the binary - for example, an automatic updater - would have to be signed by the cert that's in the original package, and as such can validate that it's a "genuine" update, as opposed to the binary being changed by a remote exploit of any sort.
4. Re:Start working at 9 AM by dkf · 2009-09-06 08:27 · Score: 1
  
  The big difference is that in Objective-C, the dispatch table is an associative array (C++ unordered_map, Java HashMap, Python dict) from strings to function pointers, not a plain array (C++ vector, Java ArrayList, Python list).
  There are a whole bunch of tricks used (e.g., the map is actually from interned strings, which makes it far quicker to do the check) yet it has the flexibility to do things like dynamic dispatch and at a speed that isn't too horrible. Clever compromise (and has much in common with the way dynamic languages manage method invocations). And one of the cleverest things about it is that only method calls are routed through this: nobody even pretends that normal function calls need the overhead of fancy dispatch.
  
  --
  "Little does he know, but there is no 'I' in 'Idiot'!"
5. Re:Start working at 9 AM by plsuh · 2009-09-07 01:41 · Score: 1
  But then you rely on the operating system to provide a method for applications to provide cache hints, and you rely on the antivirus software to provide such hints. SuperFetch tries to infer these even for applications developed prior to widespread knowledge of these hints or ported from systems that lack these hints.
  As I understand it, neither function pointer uniquing caching nor Superfetch require that the A/V or backup software provide cache hints. On Mac OS X, almost all apps load the libobjc.dylib library so caching the uniquing of function pointers is a big win for app launch times.
  
  Having my applications ready to start at 08:57 when I'm about to grab the mouse at 08:58 improves my productivity. Consider that employees have sued their employers for requiring that employees be present during application startup time but not paid until the application has fully started up.
  This may work for some, but not for others. The problem is the lack of consistency -- e.g., if I grab the mouse at 8:58 AM I get my e-mail quickly, but if I come in a little early at 8:30 AM I have to wait for it. This leads to user frustration and unnecessary force-quits of apps or hard power cycling.
  
  But who signs the developer's certificate? And what keeps malware publishers from signing their trojans?
  That's the point of the X.509 PKI system -- you have to be able to trace the signature on the app binary back to a known trusted root that signed the code-signing certificate. No, this won't prevent a malware writer from signing his or her code, but it accomplishes two things:
  It gives a traceable connection back to the author. Malware writers generally don't like this. ;-)
  It makes it impossible for the malware to inject code into an existing binary without disturbing the signature.
  The second is really the key point -- Mac OS X won't run a signed binary if the signature is present but is not consistent.
  
  Any malware that attempts to insert itself into applications will run into problems.
  Unless an application tries to insert itself as, say, an assistive technology using the accessibility API.
  The official accessibility API seems to be pretty safe from a security perspective. I haven't been able to find any reports of problems and a cursory look at the developer API docs doesn't send up any red flags. I would agree (and have long expressed the opinion to Apple) that Input Managers are a serious problem, and it looks like they've severely tightened the hole in Snow Leopard so that you need admin privs to install one. I'd like to see them gone entirely and have a proper system-level plug-in API. Now if only someone could get Microsoft to understand why ActiveX downloaded over the network is such a BAD idea... (*grumble*).
  --Paul
6. Re:Start working at 9 AM by tepples · 2009-09-07 02:00 · Score: 1
  As I understand it, neither function pointer uniquing caching nor Superfetch require that the A/V or backup software provide cache hints.
  True, because SuperFetch is an improvement to Windows caching that works around the lack of such hints.
  
  No, [code signing] won't prevent a malware writer from signing his or her code, but it accomplishes two things:
  
  It gives a traceable connection back to the author. Malware writers generally don't like this. ;-)
  It makes it impossible for the malware to inject code into an existing binary without disturbing the signature.
  3. The price of a certificate from a trusted root makes it uneconomic for some people to sign their software. Or at least that's what I've seen from Authenticode on Windows: most non-corporate-backed free software and freeware and much shareware is distributed without a signature. Likewise, homebrew applications for video game consoles use holes in the operating system's signature verification to start executing. At least Mac OS X has an option for self-signed certificates, which do #2 (make sure two binaries have the same publisher) without having to do #1 (make sure each publisher is part of a private club).
7. Re:Start working at 9 AM by plsuh · 2009-09-07 02:38 · Score: 1
  
  The price of a certificate from a trusted root makes it uneconomic for some people to sign their software. Or at least that's what I've seen from Authenticode on Windows: most non-corporate-backed free software and freeware and much shareware is distributed without a signature. Likewise, homebrew applications for video game consoles use holes in the operating system's signature verification to start executing. At least Mac OS X has an option for self-signed certificates, which do #2 (make sure two binaries have the same publisher) without having to do #1 (make sure each publisher is part of a private club).
  Grr... I just checked and a 1-year code signing cert from Comodo is $179.95, with discounts for multi-year certs. Other vendors also seem to have pretty reasonable prices. Anyone who has the time to put together a serious app (even for freeware) can afford that amount. Verisign charges an unconscionable amount (around $900 for one year!) for a code signing cert. Bleah!
  Video console homebrews are a different story, as the console makers won't sign an app that hasn't been through their (rather expensive) developer programs.
  --Paul
Re:I thought this was the shared libs always worke by Anonymous Coward · 2009-09-06 04:34 · Score: 0

A lot of people seem to be confused about operation of "shared" libraries.
Shared libraries on most platforms (mac,linux,windows..etc) are "shared" within a single processes memory space only. They are NOT "shared" between processes. Each separate process instantiates libraries separatly.
Apples change is to globally save some library state data to reduce each processes instantiation overhead when common libraries are used by multiple processes.
Apple made a rod for their own back with Obj-C by Viol8 · 2009-09-06 04:49 · Score: 1, Insightful

Perhaps Obj-C has a few nice features but personally I don't see it. If they'd stuck to C or C++ like every other version of Unix then this would never have been an issue in the first place. Plus a lot more people would have been able to cross-code for OS/X without having to learn an obscure OO version of C which never caught on in the wider IT world and is still used on practically no other system.
1. Re:Apple made a rod for their own back with Obj-C by Anonymous Coward · 2009-09-06 05:45 · Score: 1, Insightful
  
  Objective-C simplifies many design patterns. Some have language level support at the core. Objective-C is a very simply, elegant language. It's not hard to learn at all. In fact, compared to C++ it's down right plain. Personally, I don't want to waste my time and brain cells learning all the intricate, ass chapping c++ quirks. I'd be better devoting those brain cells to Haskell.
2. Re:Apple made a rod for their own back with Obj-C by mgbastard · 2009-09-06 05:46 · Score: 3, Insightful
  
  Right, because obviously the ultimate evolution of computer languages for all time is C and C++. There's never any need to further innovate that technology whatsoever.
  Are you @#$@ kidding? It wasn't that funny.
  I take issue with the assertion that nobody ever caught on with it. GNUStep? NeXT has been around for something like 15 years in industry now. EDS and others used it. Ross Perot was so impressed he invested in it and because a director at NeXT. It has a very feature rich set of frameworks associated with it, depending on your OS deployment. The only thing that sucks is Apple dropping OPENSTEP / Obj-C for Windows. But Steve didn't care about the enterprise market anymore at the time, and it might have eroded some mac hardware sales, and you couldn't very well charge a license for it. (I disagree, I think you could and can)
  
  --
  Anyone seen my low uid? last seen 10 years ago while panning the #@$# out of Taco's 'web based discussion system'
3. Re:Apple made a rod for their own back with Obj-C by ari_j · 2009-09-06 06:16 · Score: 1
  
  Not just that, but the expense of rewriting Openstep in C++ would have been ridiculous and likely would have put Apple out of business. They did the right thing, both in business terms and in technological terms. Instead of wasting time reinventing the wheel, they just got on the cart and started rolling forward. Obj-C is also not a bad language, all things considered.
4. Re:Apple made a rod for their own back with Obj-C by Anonymous Coward · 2009-09-06 06:33 · Score: 0, Insightful
  
  Right, because obviously the ultimate evolution of computer languages for all time is C and C++. There's never any need to further innovate that technology whatsoever.
  Sure there is need for that. But does Objective-C do that? The GP said he doesn't think so. You should start there if you wan't to make a point.
5. Re:Apple made a rod for their own back with Obj-C by am+2k · 2009-09-06 06:48 · Score: 1
  
  Considering what Apple did to WebObjects, my guess is that not even charging for it would have changed that decision.
6. Re:Apple made a rod for their own back with Obj-C by Anonymous Coward · 2009-09-06 07:37 · Score: 0
  
  Actually, one of the nicer features of Obj-C is the fact that it is a strict superset of C. What this means for developers is that any code written in C (and usually C++, though for different reasons) can be treated as Obj-C code, which makes it pretty easy to port such code to OS X. All that usually needs to be done is write a wrapper in Obj-C to handle all your OS X specific code.
7. Re:Apple made a rod for their own back with Obj-C by Ma8thew · 2009-09-06 10:30 · Score: 1
  
  The issue of learning the language doesn't seem to have held back iPhone development.
8. Re:Apple made a rod for their own back with Obj-C by bar-agent · 2009-09-06 10:54 · Score: 1
  
  The issue of learning the language doesn't seem to have held back iPhone development.
  Yeah, Viol8. Quit slacking off, roll up your sleeves, and get going. You're behind the curve.
  
  --
  i'd hit it so hard, if you pulled me out you'd be the king of britain [bash.org]
9. Re:Apple made a rod for their own back with Obj-C by GrahamCox · 2009-09-06 14:29 · Score: 1
  
  You personally don't see it. So? Try actually using it, maybe? The advantages of Obj-C over C/C++ are so manifold that the only way to appreciate it is to code in it. A list of features won't relay much if you don't try it. I used to think C++ would be all I'd ever need, but then I got into Obj-C and my productivity went through the roof. I could never go back now. In fact I don't know how to even express myself in C++ for the kinds of concept I can take for granted in Obj-C.
10. Re:Apple made a rod for their own back with Obj-C by Anonymous Coward · 2009-09-06 15:30 · Score: 0
  
  I'm afraid this is the normal comment from people who know C++ but have never developed anything big in Obj-C.
  Obj-C "just works" (tm), if M$ had used it all that horrid mess that was COM could have been avoided, they wouldn't need the .NET framework, and they might have even made a version of Windows that actually worked (tm) before XP came out.
  Obj-C is a huge part of what saved Apple's ass, you should try it.
11. Re:Apple made a rod for their own back with Obj-C by bonch · 2009-09-06 15:37 · Score: -1
  
  One of the more ignorant replies to this story. You seem to believe all progression should stop at C and C++. Compared to Objective-C, application development using C++ blows. Not to mention that if C and C++ are so important to you, you can freely mix them with Objective-C code anyway. As for being obscure, you may have heard of a little thing called the iPhone and its App Store which houses apps developed in Objective-C. But I guess since Viol8 of Slashdot personally doesn't see the viability of Objective-C, Apple should give it up and go back to the drawing board. Good call.
  Hell, you even added a slash for no reason in the name "OS X. Grr.
12. Re:Apple made a rod for their own back with Obj-C by fnj · 2009-09-07 13:21 · Score: 1
  
  The only thing that sucks is Apple dropping OPENSTEP / Obj-C for Windows.
  What in God's name are you talking about?
13. Re:Apple made a rod for their own back with Obj-C by fnj · 2009-09-07 13:25 · Score: 0, Flamebait
  
  So in other words you can't think of any substantive arguments in favor of ObjC?
14. Re:Apple made a rod for their own back with Obj-C by fnj · 2009-09-07 13:27 · Score: 0, Flamebait
  
  But instead of saying "I have seen perfection," can't you come up with any cogent explanations of exactly what features make ObjC nso divine?
15. Re:Apple made a rod for their own back with Obj-C by tim1724 · 2009-09-07 15:36 · Score: 1
  
  The only thing that sucks is Apple dropping OPENSTEP / Obj-C for Windows.
  What in God's name are you talking about?
  Back when Apple's aquisition of NeXT was first announced, Apple had indicated that they'd continue to support OPENSTEP Enterprise (the Windows implementation of OpenStep). But it was killed off pretty quick.
  
  --
  -- Tim Buchheim
16. Re:Apple made a rod for their own back with Obj-C by vonFinkelstien · 2009-09-07 15:43 · Score: 1
  
  You could cross-compile code for Windows and Next Machines in NeXT's version of X-Code back in the day.
17. Re:Apple made a rod for their own back with Obj-C by fnj · 2009-09-07 18:00 · Score: 1
  
  Thank you. I understand. As many times as I read the sentence I kept interpreting it as "dropping OPENSTEP / Obj-C for [i.e. in favor of] Windows." Was that before or after M$ dropped a bunch of dollar bills on Apple?
18. Re:Apple made a rod for their own back with Obj-C by SuiteSisterMary · 2009-09-08 06:41 · Score: 1
  
  "No one can be...told...what ObjC is. You have to experience it for yourself."
  
  --
  Vintage computer games and RPG books available. Email me if you're interested.
19. Re:Apple made a rod for their own back with Obj-C by fnj · 2009-09-16 07:58 · Score: 1
  
  Obviously the answer is "no", and obviously asshole moderators abound.
20. Re:Apple made a rod for their own back with Obj-C by fnj · 2009-09-16 15:30 · Score: 1
  
  Obviously, the answer is "no", and obviously asshole moderators abound.
I heard of it, and USED IT, before that... apk by Anonymous Coward · 2009-09-06 04:50 · Score: 0

"In other words, Apple just re-invented Superfetch" - by LO0G (606364) on Sunday September 06, @10:36AM (#29331275)
On that note? Well, I could say that Microsoft only "ripped off" ideas I've been using since the early 1990's (first on software ramdisks, & later on SSD's too, per how I use them noted in this post here on /., today (& long before THAT, many times here & elsewhere online)):
http://hardware.slashdot.org/comments.pl?sid=1359547&cid=29332071
Microsoft's only using a VARIATION OF MY IDEAS.
Ideas that took EEC Systems/SuperSpeed.com to a FINALIST position @ Microsoft's own Tech-Ed, 2 yrs. in a row, in its hardest category: SQLServer Performance Enhancement, albeit not for "home/end user oriented tasks" (which I list some of above & how I use it @ home @ least)...
That was for "back office app" perf. enhancement, & that url above shows proofs of that much for WebServers, File Servers, & DB Servers (from TechReport.com, in regards to Webserver, FileServer, & DB Server performance gains when using a TRUE SSD, like the IRAM).
E.G.-> AND? When that work showed improvements on SQLServer 6.5 & below, which used HDD space for various ops? Microsoft later "turned around", & made those ops take place in RAM...
(Which amounts to the SAME THING as doing it on a ramdisk in software really, & MUCH FASTER than HDD space could do it (MS uses a dedicated array/buffer in RAM now in SQLServer, because it works, for superior performance on DB work, bigtime)).
APK
P.S.=> More proof of my involvement here in this arena, goes back in WRITTEN PUBLICATION no less, as far back as 1996, here:
Windows NT Magazine (now Windows IT Pro) April 1997 "BACK OFFICE PERFORMANCE" issue, page 61
(&, for work done for EEC Systems/SuperSpeed.com on PAID CONTRACT (writing portions of their SuperCache program increasing its performance by up to 40% via my work) albeit, for their SuperDisk & HOW TO APPLY IT, took them to a finalist position @ MS Tech Ed, two years in a row)... apk
1. Re:I heard of it, and USED IT, before that... apk by Anonymous Coward · 2009-09-06 15:24 · Score: 1, Insightful
  
  Oh boy, its my good buddy Alexander Peter Kowalski
  Why do you always have to chime in with some bizarrely formatted story completely tangential to the topic at hand?
  I'm surprised you're not whining about the HOSTS file today. Boo-hoo, I can't put 0 in the HOSTS file. STFU.
  Go back and write some more useless Delphi shit you crazy fuck.
What? by gbutler69 · 2009-09-06 04:55 · Score: 1

Hmm?? I think one could make a very meaningful comparison of the efficiency of Tree vs. Cat. Energy consumed vs. usefulness. Tree wins methinks!
Also, so what if they're "different languages"? If they were the "same language" there'd be nothing to compare. Do you go around comparing your right eye to your right eye?

--
Over-the-top Response Guy! Giving "Over-the-Top Responses" since 1970.
1. Re:What? by Anonymous Coward · 2009-09-06 09:35 · Score: 0
  
  Which one is more efficient at killing mice? Which one is more efficient at photosynthesis?
  "Different languages" means that they have radically different capabilities, not just that they aren't identical. It makes sense to compare the efficiencies of, say, C and Pascal, or SmallTalk and Ruby, but little sense to compare, say, Prolog and FORTRAN or Lisp and BASIC.
  People tend to think of Objective-C as being C++ with funny syntax, but they have radically different capabilities, so saying that Objective-C is less efficient makes no sense. It's more efficient at some stuff, and less efficient at others.
ta3o by Anonymous Coward · 2009-09-06 07:24 · Score: -1, Redundant

or chair, return they started to Thes3 eArly OpenBSD, as the
I don't get it. by Ant+P. · 2009-09-06 07:47 · Score: 1, Insightful

Why don't they (any OS) just add something onto the generic filesystem caching layer to keep executable bits in RAM as long as the input files stay the same? If it was done that way you could theoretically reuse it for interpreted code as well.
1. Re:I don't get it. by Anonymous Coward · 2009-09-07 01:36 · Score: 0
  
  They do (unless memory pressure requires that the pages be reclaimed for other uses). In fact, not just for executable files, but for any kind of file.
  The problem is that executable files aren't unchanging. When you modify an executable image in one process, you need to make private copies of the pages you touch, which obviously can't be shared anymore. (And incidentally need to be retained in memory or swap, since you can't write them back to the executable file.)
  I'm not sure how Objective C does it, but if you have common bits of data that need to be modified in a large number of places, you could potentially have a huge impact on how much memory you're using. Position-independent code (PIC) usually eliminates this issue, though.
  However, it sounds like the main benefit is similar to prelinking, resulting in a big speedup for loading system libraries that many applications use, by minimizing the number of process-specific changes that need to be made. That you can also reduce memory usage by sharing the resulting prelinked unique selector table thingy sounds like a side benefit.
  Incidentally, writes to files happen in the cache first, then to the file system on disk. So there's no actual checking of the input files for changes--the operating system already knows if a file differs from the cache because it performs the change in the cache first.
ObjC is a modern, rich platform by SuperKendall · 2009-09-06 07:55 · Score: 2, Interesting

Perhaps Obj-C has a few nice features but personally I don't see it. If they'd stuck to C or C++ like every other version of Unix then this would never have been an issue in the first place.
But you can use either of those perfectly well mixed with ObjC calls.
ObjC is a relatively small set of additions to standard-C, so it really doesn't take that long to pick up the syntax changes if you've encountered C before, while at the same time it allows for some very nice dynamic behavior and things like introspection. The language has evolved to support things like garbage collection (though that specific feature is not available on the iPhone due to performance constraints).
What you are really overlooking though is that Objective-C that Apple uses, has a very rich and diverse set of foundation classes (some inherited from the NeXT days) - just as wide in scope as Java. Any modern language simply has to have a giant toolbox to help get common tasks done, and that's going to be the thing that takes the most time to learn. Happily, Objective-C has a fairly consistent set of tools and conventions, that make learning new parts easier once you have learned a few others.

--
"There is more worth loving than we have strength to love." - Brian Jay Stanley
Re:I thought this was the shared libs always worke by Anonymous Coward · 2009-09-06 11:09 · Score: 1, Interesting

Shared libraries on most platforms (mac,linux,windows..etc) are "shared" within a single processes memory space only. They are NOT "shared" between processes. Each separate process instantiates libraries separatly.
I'm not so sure about that. Typically, code in shared libraries is re-entrant and code pages are loaded once, then mapped into the address space of the process using them. I don't know of any modern OS that wastefully makes a copy of the library's code for each process.
Re:I thought this was the shared libs always worke by dmesg0 · 2009-09-06 11:23 · Score: 1

That's simply not true. On Linux the text segments of shared libraries are shared between processes (there is a trick to create non-PIC non-shareable dynamic libraries on 32-bit x86, but it's rarely used).
I don't know about other platforms, but I wouldn't be surprised if they do something to share the memory as well.
Kernel by Metabolife · 2009-09-06 14:37 · Score: 1

They probably just rolled in the 2.6.31 kernel.
Here comes update_prebinding fashion again by Ilgaz · 2009-09-06 14:52 · Score: 1

Using OS X/Mac since 10.2.8, I haven't seen another abused tool like "update_prebinding" even while it is a very risky process in pre 10.5 systems since it deals with actual binary headers.
Also thanks to uninformed IT blogs etc, people always considered prebinding a thing which will go away in next release. Like, Apple is really stupid to do such thing. They basically misunderstood the added flexibility to prebinding scheme where tools without (or broken) prebinding will continue to run.
Anyway, want to see how much Apple users are abused by some shareware developers? Just watch for a applescript to basically issue this command and asks for money or donation. I don't have 10.6 but on 10.5, in its FIRST line of man page (man update_prebinding), Apple states "normally, there shouldn't be any need to issue this command manually" or something equivalent to that. On pre 10.5, like 10.4.11, it can get catastrophic if you keep doing it, as explained on article http://unsanity.org/archives/mac_os_x/shock_and_awe.php
Unless you lived a power loss in middle of a OS X/Quicktime update or kernel crash, there shouldn't be ANY reason to manually update prebinding. In fact, it can lead to a horrible cache fragmentation which may slow things down. Don't fix a working thing.
I have a question: Do you like The Beatles? by Anonymous Coward · 2009-09-06 20:43 · Score: -1, Troll

Listen to your "theme song", by them. It's entitled: "I'm a LOSER"
APK
P.S.=> Fits you, perfectly... you've never done anything worth anything, & it shows. You truly are, the "ANONYMOUS COWARD", & because of that? You'll never amount to anything, & that is that... apk
1. Re:I have a question: Do you like The Beatles? by Anonymous Coward · 2009-09-07 02:19 · Score: 1, Funny
  
  This line is posted with BOLD text and one word randomly capitalised! Have you ever been so far as to want to look more like that? I was wearing an Onion on my belt, which was the style at the time...have you ever... ever felt like this? More random bold TEXT.
  
  Have I ever told you ABOUT the time I held Bill Gates TOWEL?
  
  P.S =>_|_|_|_|_+-+-+-+-+-+-!>!>!>!>! Whoop whoop whoop whoop! Nurse!
Re: by clint999 · 2009-09-07 00:30 · Score: -1

Dude, I think you're hearing things that people aren't saying. The article describes how apple has improved their dynamic loading. The author doesn't claim they invented it. Apple doesn't claim they invented it. Nobody said anything about amazing new technologies Apple created.

--
College-Pages.com - Online Colleges, Degrees, and Programs
Cross-platform code signing costs by tepples · 2009-09-07 02:54 · Score: 1

I just checked and a 1-year code signing cert from Comodo is $179.95, with discounts for multi-year certs. Other vendors also seem to have pretty reasonable prices.
That's at least on the order of $100 per platform. The certificate for Windows is $179.95 per year, and the certificate for a secure web site from which to distribute copies of the software is another $99 per year. It gets even more expensive to target more than one platform: the certificate for XNA is $99 per year, the certificate for iPod Touch is $99 per year, and by the time one has ported an application to all the platforms that his audience uses, he'd be out of his hobby money.

Anyone who has the time to put together a serious app (even for freeware) can afford that amount.
Say I develop a video game and want to distribute it to the public. How would I recover the nearly $480 per year across three platforms without selling either copies or advertisements? It's almost enough to push someone toward a less expensive hobby.
1. Re:Cross-platform code signing costs by plsuh · 2009-09-07 12:49 · Score: 1
  
  I just checked and a 1-year code signing cert from Comodo is $179.95, with discounts for multi-year certs. Other vendors also seem to have pretty reasonable prices.
  That's at least on the order of $100 per platform. The certificate for Windows is $179.95 per year, and the certificate for a secure web site from which to distribute copies of the software is another $99 per year. It gets even more expensive to target more than one platform: the certificate for XNA is $99 per year, the certificate for iPod Touch is $99 per year, and by the time one has ported an application to all the platforms that his audience uses, he'd be out of his hobby money.
  Hold on, most code signing CA's include both the codeSigning and msCodeCom usage extensions in the same certificate so there's no need to buy multiple code signing certs. Unless you're conducting an e-commerce transaction (in which case you're no longer a hobbyist), there's no need for a website cert -- and even then I've found website certs for as little as $15/year. Mac OS X/iPhone code signing certs just require the code signing extension, so they just work. Ditto XNA. To join the iPhone developer program is $99/year, so we're up to $280/year, or about $24/month. This is well within the budget for most hobbyists. Most hobbyists won't be faced with multi-platform issues anyway. I sure as heck don't have the time to write and maintain a cross-platform app -- keeping up with Mac OS X is enough for me.
  --Paul
2. Re:Cross-platform code signing costs by Anonymous Coward · 2009-09-08 12:13 · Score: 0
  
  ...and by the time one has ported an application to all the platforms that his audience uses, he'd be out of his hobby money...How would I recover the nearly $480 per year across three platforms without selling either copies or advertisements? It's almost enough to push someone toward a less expensive hobby.
  Actually, that's not all that bad for a hobby. If you think it is, let me humbly suggest that restoring/upgrading classic muscle cars is not one of the less expensive alternatives. You could spend as much on just a performance carburetor, and you don't even want to know what a crate engine costs.
  
  Oh, and the desire to recover costs is not commonly considered intrinsic to most hobbies, nor even considered by most hobbyists at all. For every philatelist who finds a stamp that nets him 6 figures, there are far more who engage in the hobby purely for the joy of it, never expecting any other reward.
  
  - T
Grow up loser by Anonymous Coward · 2009-09-07 03:35 · Score: 0

See subject line above, & rinse/lather/repeat.
Have you considered decaf? by Anonymous Coward · 2009-09-08 15:54 · Score: 0

See subject and lay off the profanity and coffee.