Editing Carbon (API) (section)

==History==
[[File:Adobe ImageReady 7.0 running on Mac OS X.png|thumb|right|275px| "Carbonized" application [[Adobe Systems]] [[Adobe ImageReady|ImageReady]] v.7.0 running directly on [[macOS|Mac OS X]] version [[Mac OS X v10.2|10.2]]]]

===Classic Mac OS programming===
The [[Classic Mac OS|original Mac OS]] used [[Pascal (programming language)|Pascal]] as its primary development platform, and the APIs were heavily based on Pascal's [[call semantics]]. Much of the [[Macintosh Toolbox]] consisted of [[subroutine|procedure calls]], passing information back and forth between the API and program using a variety of [[data structure]]s based on Pascal's [[variant record]] concept.

Over time, a number of [[object library|object libraries]] evolved on the Mac, notably the [[Object Pascal]] library [[MacApp]] and the [[THINK C]] Think Class Library, and later versions of MacApp and [[CodeWarrior]]'s PowerPlant in [[C++]]. 

===Rhapsody===
With the purchase of [[NeXT]] in late 1996, Apple developed a new operating system strategy based largely on the existing [[OpenStep#OPENSTEP for Mach|OPENSTEP for Mach]] platform. The new [[Rhapsody (operating system)|Rhapsody]] OS strategy was relatively simple; it retained most of OpenStep's existing object libraries under the name "Yellow Box", ported the existing [[GUI]] in OPENSTEP for Mach and made it look more Mac-like, ported several major [[API]]s from the Mac OS to Rhapsody's underlying [[Unix-like]] system (notably [[QuickTime]] and [[AppleSearch]]), and added an emulator known as the "Blue Box" that ran existing Mac OS software.

When this plan was revealed at the [[Worldwide Developers Conference]] (WWDC) in 1997 there was some push-back from existing Mac OS developers who were upset that their code bases would be effectively locked into an emulator that was unlikely to ever be updated. They took to calling the Blue Box the "penalty box".{{citation needed|date=March 2014}} Larger developers like [[Microsoft]] and [[Adobe Systems|Adobe]] balked outright, and refused to consider porting to OpenStep, which was so different from the existing Mac OS that there was little or no compatibility.

Apple took these concerns to heart. When [[Steve Jobs]] announced Apple's change in direction at the next WWDC in 1998, he stated that "what developers really wanted was a modern version of the Mac OS, and Apple [was] going to deliver it".

The original Rhapsody concept, with only the Blue Box for running existing Mac OS software, was eventually released in 1999 as [[Mac OS X Server 1.0]]. This was the only release based on the original Rhapsody concept.

===Cocoa and Carbon===
In order to offer a real and well supported upgrade path for existing Mac OS code bases, Apple introduced the Carbon system. Carbon consists of many libraries and functions that offer a Mac-like API, but running on top of the underlying Unix-like OS, rather than a copy of the Mac OS running in emulation. The Carbon libraries are extensively cleaned up, modernized and better "protected". While the Mac OS was filled with APIs that shared memory to pass data, under Carbon all such access was re-implemented using [[mutator method|accessor]] [[subroutine]]s on [[opaque data type]]s. This allowed Carbon to support true [[Computer multitasking|multitasking]] and [[memory protection]], features Mac developers had been requesting for a decade. Other changes from the pre-existing API removed features which were conceptually incompatible with Mac OS X, or simply obsolete. For example, applications could no longer install [[interrupt handler]]s or [[device driver]]s.

In order to support Carbon, the entire Rhapsody model changed. Whereas Rhapsody would effectively be OpenStep with an emulator, under the new system both the OpenStep and Carbon API would, where possible, share common code. To do this, many of the useful bits of code from the lower-levels of the OpenStep system, written in Objective-C and known as Foundation, were re-implemented in pure C. This code became known as [[Core Foundation]], or CF for short. A version of the Yellow Box ported to call CF became the new [[Cocoa (API)|Cocoa]] API, and the Mac-like calls of Carbon also called the same functions. Under the new system, Carbon and Cocoa were peers. This conversion would normally have slowed the performance of Cocoa as the object methods called into the underlying C libraries, but Apple used a technique they called ''toll-free [[Bridging (programming)|bridging]]'' to reduce this impact.<ref>{{cite web |title=Concepts in Objective-C Programming: Toll-Free Bridging |date=2012 |url=https://developer.apple.com/library/content/documentation/General/Conceptual/CocoaEncyclopedia/Toll-FreeBridgin/Toll-FreeBridgin.html |website=developer.apple.com |access-date=2017-05-08}}</ref>

As part of this conversion, Apple wrote a new window server and [[2D computer graphics|graphics engine]] from scratch to replace the licence-encumbered [[Display PostScript]]: the [[Quartz (graphics layer)|Quartz]] (which has been called "Display PDF").<ref>{{cite web |last=Siracusa |first=John |date=2000 |url=http://archive.arstechnica.com/reviews/1q00/macos-x-gui/macos-x-gui-4.html |title=Mac OS X Update: Quartz & Aqua |website=archive.arstechnica.com |access-date=2017-05-08}}</ref> Quartz provided C API calls that could be used from either Carbon or Cocoa. The underlying operating system itself was further isolated and released as [[Darwin (operating system)|Darwin]].

===Release and evolution===
Carbon was introduced in incomplete form in 2000, as a shared library backward-compatible with 1997's Mac OS 8.1. This version allowed developers to port their code to Carbon without losing the ability for those programs to run on existing Mac OS machines. Porting to Carbon became known as "Carbonization". Official Mac OS X support arrived in 2001 with the release of [[Mac OS X v10.0]], the first public version of the new OS. Carbon was very widely used in early versions of Mac OS X by almost all major software houses, even by Apple. The [[Finder (software)|Finder]], for instance, remained a Carbon application for many years, only being ported to Cocoa with the release of Mac OS X 10.6 in 2009.<ref>{{cite web|title=Apple moving Finder to Cocoa|url=http://www.cnet.com/uk/news/apple-moving-finder-to-cocoa/|website=[[CNET]]|first1=Tom|last1=Krazit|access-date=2015-05-21|date=2008-10-17 |archive-url = https://web.archive.org/web/20150711154619/http://www.cnet.com/uk/news/apple-moving-finder-to-cocoa/ |archive-date = 2015-07-11}}</ref>

The transition to [[64-bit computing|64-bit]] Macintosh applications beginning with [[Mac OS X Leopard|Mac OS X v10.5]], released October 26, 2007, brought the first major limitations to Carbon. Apple does not provide compatibility between the Macintosh [[graphical user interface]] and the C programming language in the 64-bit environment, instead requiring the use of the [[Objective-C]] dialect with the Cocoa API.<ref>{{cite web|url=https://developer.apple.com/documentation/Carbon/Conceptual/Carbon64BitGuide/Introduction/Introduction.html |archive-url=https://web.archive.org/web/20090611041727/http://developer.apple.com/documentation/Carbon/Conceptual/Carbon64BitGuide/Introduction/Introduction.html |archive-date=2009-06-11 |title=Introduction to 64-Bit Guide for Carbon Developers|author=Apple Inc.}}</ref> Many commentaries took this to be the first sign of Carbon's eventual disappearance, a position that was re-enforced when Apple stated no new major additions would be added to the Carbon system,<ref>{{cite web|url=https://developer.apple.com/documentation/Carbon/Conceptual/Carbon64BitGuide/PortingTo64Bit/PortingTo64Bit.html#//apple_ref/doc/uid/TP40004381-CH3-SW2 |archive-url = https://web.archive.org/web/20090804014545/http://developer.apple.com/documentation/Carbon/Conceptual/Carbon64BitGuide/PortingTo64Bit/PortingTo64Bit.html |archive-date = 2009-08-04 |work = Modifying Your Application to Use 64-Bit Addressing | title = Choosing a Development Path for Your Carbon User Interface |author = Apple Inc}}</ref><ref>{{Cite web |last=Siracusa |first=John |date=2008-04-03 |title=Rhapsody and blues |url=https://arstechnica.com/staff/2008/04/rhapsody-and-blues/ |access-date=2023-02-05 |website=Ars Technica |language=en-us}}</ref> and further reinforced with its deprecation in 2012.

===Transition to Cocoa===
Despite the purported advantages of Cocoa, the need to rewrite large amounts of legacy code slowed the transition of Carbon-based applications, famously with [[Adobe Photoshop]],<ref>{{cite web|url=http://blogs.adobe.com/jnack/2008/04/photoshop_lightroom_and_adobes_64-bit_road.html|title=Photoshop, Lightroom, and Adobe's 64-bit roadmap|author=John Nack |archive-url=https://web.archive.org/web/20150414030843/http://blogs.adobe.com/jnack/2008/04/photoshop_lightroom_and_adobes_64-bit_road.html |archive-date=2015-04-14}}</ref> which was eventually updated to Cocoa in April 2010. This also extended to Apple's own flagship software packages, as [[iTunes]]<ref>{{cite web|url=https://arstechnica.com/apple/news/2010/09/itunes-10-hands-on-snappier-performance-questionable-ui-choices.ars|title=iTunes 10 hands-on: snappier performance, questionable UI choices|author=Chris Foresman |date=September 3, 2010|archive-url=https://web.archive.org/web/20150402183024/http://arstechnica.com/apple/2010/09/itunes-10-hands-on-snappier-performance-questionable-ui-choices/ |archive-date=2015-04-02}}</ref> the Finder application, and [[Final Cut Pro]] (as well as the features in the [[QuickTime]] engine that powers it<ref>{{cite web|url=https://arstechnica.com/apple/reviews/2009/08/mac-os-x-10-6.ars|title=Mac OS X 10.6 Snow Leopard: the Ars Technica review|author=John Siracusa |date=September 2009|archive-url=https://web.archive.org/web/20140713115247/http://arstechnica.com/apple/2009/08/mac-os-x-10-6/ |archive-date=2014-07-13}}</ref>) remained written in Carbon for many years. iTunes, Finder, and Final Cut Pro have since been released in Cocoa versions.

===Deprecation and discontinuation===
In 2012, with the release of OS X 10.8 Mountain Lion, most Carbon APIs were considered deprecated. The APIs were still accessible to developers and all Carbon applications still ran, but the APIs would no longer be updated. On June 28, 2017, Apple announced that 32-bit software for macOS, such as all Carbon applications, would no longer be supported “without compromise” on versions of macOS after [[macOS High Sierra|macOS 10.13 High Sierra]].<ref>{{cite web|url=https://developer.apple.com/news/?id=06282017a|title=64-bit Requirement for Mac Apps|author=Apple Inc.|author-link=Apple Inc.|date=2017-06-28|access-date=2018-02-18|archive-url=https://web.archive.org/web/20180130123005/https://developer.apple.com/news/?id=06282017a|archive-date=2018-01-30}}</ref> [[macOS Catalina|macOS 10.15 Catalina]] officially removed support for 32-bit applications, including all Carbon applications.<ref>{{cite web|url=https://www.macrumors.com/guide/32-bit-mac-apps/|title=32-Bit Apps 'Not Optimized for Your Mac' to Stop Working on macOS Catalina|author=MacRumors|date=June 4, 2019|access-date=August 10, 2019}}</ref>