Structure and Interpretation of Computer Programmers

I make it easier and faster for you to write high-quality software.

Saturday, October 19, 2013

Happy 19th birthday, Cocoa!

On October 19th, 1994 NeXT Computer, Inc. (later NeXT Software, Inc.) published a specification for OpenStep, a cross-platform interface for application programming, based on their existing Objective-C frameworks and the Display PostScript graphics system.

A little bit of history

First there came message-passing object oriented programming, in the form of Smalltalk. Well, not first, I mean first there was Simula 67, and there were even things before that but every story has to start somewhere. In 1983 Brad Cox added Smalltalk messaging to the C language to create the Object-Oriented pre-compiler. In his work with Tom Love at Productivity Products International, this eventually became Objective-C.

Object-Oriented Programming: an Evolutionary Approach

If PPI (later Stepstone) had any larger customers than NeXT, they had none that would have a bigger impact on the software industry. In 1988 NeXT released the first version of their UNIX platform, NEXTSTEP. Its application programming interface combined the “application kit” of Objective-C objects representing windows, menus, and views with Adobe’s Display PostScript to provide a high-fidelity (I mean, if you like grey, I suppose) WYSIWYG app environment.

NeXTSTEP Programming Step One: Object-Oriented Applications

N.B.: my reason for picking the Garfinkel and Mahoney book will become clear later. It happens to be the book I learned to make apps from, too.

Certain limitations in the NEXTSTEP APIs became clear. I will not exhaustively list them nor attempt to put them into any sort of priority, suffice it to say that significant changes became necessary. When the Enterprise Objects Framework came along, NeXT also introduced the Foundation Kit, a “small set of base utility classes” designed to promote common conventions, portability and enhanced localisation through Unicode support. Hitherto, applications had used C strings and arrays.

It was time to let app developers make use of the Foundation Kit. For this (and undoubtedly other reasons), the application kit was rereleased as the App Kit, documented in the specification we see above.

The release of OpenStep

OpenStep was not merely an excuse to do application kit properly, it was also part of NeXT’s new strategy to license its software and tools to other platform vendors rather than limiting it to the few tens of thousands of its own customers. Based on the portable Foundation Kit, NeXT made OpenStep for its own platform (now called OPENSTEP) and for Windows NT, under the name OpenStep Enterprise. Sun Microsystems licensed it for SPARC Solaris, too.

What happened, um, NeXT

The first thing to notice about the next release of OpenStep is that book cover designers seem to have discovered acid circa 1997.

Rhapsody Developer's Guide

Everyone’s probably aware of NeXT’s inverse takeover of Apple at the end of 1996. The first version of OpenStep to be released by Apple was Rhapsody, a developer preview of their next-generation operating system. This was eventually turned into a product: Mac OS X Server 1.0. Apple actually also released another OpenStep product: a y2k-compliant patch to NeXT’s platform in late 1999.

It’s kindof tempting to tell the rest of the story as if the end was clear, but at the time it really wasn’t. With Rhapsody itself it wasn’t clear whether Apple would promote Objective-C for OpenStep (now called “Yellow Box”) applications, or whether they would favour Yellow Box for Java. The “Blue Box” environment for running Mac apps was just a virtual machine with an older version of the Macintosh system installed, there wasn’t a way to port Mac software natively to Rhapsody. It wasn’t even clear whether (or if so, when) the OpenStep software would become a consumer platform, or whether it was destined to be a server for traditional Mac workgroups.

That would come later, with Mac OS X, when the Carbon API was introduced. Between Rhapsody and Mac OS X, Apple introduced this transition framework so that “Classic” software could be ported to the new platform. They also dropped one third of the OpenStep-specified libraries from the system, as Adobe’s Display PostScript was replaced with Quartz and Core Graphics. Again, reasons are many and complicated, though I’m sure someone noticed that if they released Mac OS X with the DPS software then their bill for Adobe licences would increase by a factor of about 1,000. The coloured box naming scheme was dropped as Apple re-used the name of their stagecast creator software: Cocoa.

So it pretty much seemed at the time like Apple were happy to release everything they had: UNIX, Classic Mac, Carbon, Cocoa-ObjC and Cocoa-Java. Throw all of that at the wall and some of it was bound to stick.

Building Cocoa Applications

Over time, some parts indeed stuck while others slid off to make some sort of yucky mess at the bottom of the wall (you know, it is possible to take an analogy too far). Casualties included Cocoa-Java, the Classic runtime and the Carbon APIs. We end in a situation where the current Mac platform (and, by slight extension, iOS) is a direct, and very close, descendent of the OpenStep platform specified on this day in 1994.

Happy birthday, Cocoa!

posted by Graham at 10:30  

Wednesday, October 9, 2013

Conflicts in my mental model of Objective-C

My worldview as it relates to the writing of software in Objective-C contains many items that are at odds with one another. I either need to resolve them or to live with the cognitive dissonance, gradually becoming more insane as the conflicting items hurl one another at my cortex.

Of the programming environments I’ve worked with, I believe that Objective-C and its frameworks are the most pleasant. On the other hand, I think that Objective-C was a hack, and that the frameworks are not without their design mistakes, regressions and inconsistencies.

I believe that Objective-C programmers are correct to side with Alan Kay in saying that the designers of C++ and Java missed out on the crucial part of object-oriented programming, which is message passing. However I also believe that ObjC missed out on a crucial part of object-oriented programming, which is the compiler as an object. Decades spent optimising the compile-link-debug-edit cycle have been spent on solving the wrong problem. On which topic, I feel conflicted by the fact that we’ve got this Smalltalk-like dynamic language support but can have our products canned for picking the same selector name as some internal secret stuff in someone else’s code.

I feel disappointed that in the last decade, we’ve just got tools that can do the same thing but in more places. On the other hand, I don’t think it’s Apple’s responsibility to break the world; their mission should be to make existing workflows faster, with new excitement being optional or third-party. It is both amazing and slightly saddening that if you defrosted a cryogenically-preserved NeXT application programmer, they would just need to learn reference counting, blocks and a little new syntax and style before they’d be up to speed with iOS apps (and maybe protocols, depending on when you threw them in the cooler).

Ah, yes, Apple. The problem with a single vendor driving the whole community around a language or other technology is that the successes or failures of the technology inevitably get caught up in the marketing messages of that vendor, and the values and attitudes ascribed to that vendor. The problem with a community-driven technology is that it can take you longer than the life of the Sun just to agree how lambdas should work. It’d be healthy for there to be other popular platforms for ObjC programming, except for the inconsistencies and conflicts that would produce. It’s great that GNUstep, Cocotron and Apportable exist and are as mature as they are, but “popular” is not quite the correct adjective for them.

Fundamentally I fear a world in which programmers think JavaScript is acceptable. Partly because JavaScript, but mostly because when a language is introduced and people avoid it for ages, then just because some CEO says all future websites must use it they start using it, that’s not healthy. Objective-C was introduced and people avoided it for ages, then just because some CEO said all future apps must use it they started using it.

I feel like I ought to do something about some of that. I haven’t, and perhaps that makes me the guy who comes up to a bunch of developers, says “I’ve got a great idea” and expects them to make it.

posted by Graham at 21:17  

Saturday, October 5, 2013

Reading List

I was asked “what books do you consider essential for app making”? Here’s the list. Most of these are not about specific technologies, which are fleeting and teach low-level detail. Those that are tech-specific also contain a good deal of what and why, in addition to the coverage of how.

This post is far from exhaustive.

I would recommend that any engineer who has not yet read it should read Code Complete 2. Then I would ask them the top three things they agreed with and top three they disagreed with, as criticality is the hallmark of a good engineer :-).

Other books I have enjoyed and learned from and I believe others would too:

  • Steve Krug, “Don’t make me think!”
  • Michael Feathers, “Refactoring” and “Working Effectively with Legacy Code”
  • Bruce Tate, “Seven languages in seven weeks”
  • Jez Humble and David Farley, “Continuous Delivery”
  • Hunt and Thomas, “The Pragmatic Programmer”
  • Gerald Weinberg, “The psychology of computer programming”
  • David Rice, “Geekonomics”
  • Robert M. Pirsig, “Zen and the art of motorcycle maintenance”
  • Alan Cooper, “About Face 3”
  • Jeff Johnson, “Designing with the mind in mind”
  • Fred Brooks, “the design of design”
  • Kent Beck, “Test-Driven Development”
  • Mike Cohn, “User stories applied”
  • Jef Raskin, “The humane interface”

Most app makers are probably doing object-oriented programming. The books that explain the philosophy of this and why it’s important are Meyer’s “Object-oriented software construction” and Cox’s “Object-oriented programming an evolutionary approach”.

posted by Graham at 19:56  

Powered by WordPress