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Happy Birthday, Objective-C!

OK, I have to admit that I actually missed the party. Brad Cox first described his “Object-Oriented pre-compiler”, OOPC, in The January 1983 issue of ACM SIGPLAN Notices.

This describes the Object Oriented Pre-Compiler, OOPC, a language and a run-time library for producing C programs that operate by the run-time conventions of Smalltalk 80 in a UNIX environment. These languages offer Object Oriented Programming in which data, and the programs which may access it, are designed, built and maintained as inseparable units called objects.

Notice that the abstract has to explain what OOP is: these were early days at least as far as the commercial software industry viewed objects. Reading the OOPC paper, you can tell that this is the start of what became known as Objective-C. It has a special syntax for sending Smalltalk-style messages to objects identified by pointers to structures, though not the syntax you’ll be used to:

someObject = {|Object, "new"|};
{|myArray, "addObject:", someObject|};

The infix notation [myArray addObject:someObject]; came later, but by 1986 Cox had published the first edition of Object-Oriented Programming: An Evolutionary Approach and co-founded Productivity Products International (later Stepstone) to capitalise on the Objective-C language. I’ve talked about the version of ObjC described in this book in this post, and the business context of this in Software ICs and a component marketplace.

It’s this version of Objective-C, not OOPC, that NeXT licensed from PPI as the basis of the Nextstep API (as distinct from the NEXTSTEP operating system: UNIX is case sensitive, you know). They built the language into a fork of the GNU Compiler Collection, and due to the nature of copyleft this meant they had to make their adaptations available, so GCC on other platforms gained Objective-C too.

Along the way, NeXT added some features to the language: compiler-generated static instances of string classes, for example. They added protocols: I recorded an episode of NSBrief with Saul Mora discussing how protocols were originally used to support distributed objects, but became important design tools. This transformation was particularly accelerated by Java’s adoption of protocols as interfaces. At some (as far as I can tell, not well documented) point in its life, Stepstone sold the rights to ObjC to NeXT, then licensed it back so they could continue supporting their own compiler.

There isn’t a great deal of change to Objective-C from 1994 for about a decade, despite or perhaps due to the change of stewardship in 1996/1997 as NeXT was purchased by Apple. Then, in about 2003, Apple introduced language-level support for exceptions and critical sections. In 2007, “Objective-C 2.0” was released, adding a collection enumeration syntax, properties, garbage collection and some changes to the runtime library. Blocks—a system for supporting closures that had been present in Smalltalk but missing from Objective-C—were added in a later release that briefly enjoyed the name “Objective-C 2.1”, though I don’t think that survived into the public release. To my knowledge 2.0 is the only version designation any Apple release of Objective-C has had.

Eventually, Apple observed that the autozone garbage collector was inappropriate for the kind of software they wanted Objective-C programmers to be making, and incorporated reference-counted memory management from their (NeXT’s, initially) object libraries into the language to enable Automatic Reference Counting.

And that’s where we are now! But what about Dr. Cox? Stepstone’s business was not the Objective-C language itself, but software components, including ICPak101, ICPak201 and the TaskMaster environment for building applications out of objects. It turned out that the way they wanted to sell object frameworks (viz. in a profitable way) was not the way people wanted to buy object frameworks (viz. not at all). Cox turned his attention to Digital Rights Management, and warming up the marketplace to accept pay-per-use licensing of digital artefacts. He’s since worked on teaching object-oriented programming, enterprise architecture and other things; his blog is still active.

So, Objective-C, I belatedly raise my glass to you. You’re nearly as old as I am, and that’s never likely to change. But we’ve both grown over that time, and it’s been fun growing up with you.