TweetFollow Us on Twitter

NeXT for Mac Devs
Volume Number:6
Issue Number:12
Column Tag:The Cross Developer

NeXT for Mac Programmers

By C. Keith Ray, Irving, TX

NeXT programming for Mac Programmers

Object oriented programming is a hot topic in the press recently, but people in the industry even now may not understand what all the excitement is about. I am a Macintosh programmer who has lately been developing an application on the NeXT cube, which is today the only machine for the mass market that requires programming in an object-oriented language. (Of course, traditional text-based Unix programming can be done in standard C.) And while it isn’t strictly required, NeXT strongly encourages the use of Interface Builder, a kind of “resource editor” for linking together the objects that comprise a NextStep-using application. Object-oriented programming is, in its simplest explanation, a way of structuring code in a manner somewhat different from the usual methods of structured programming. However, it turns out that dynamic allocation of objects, polymorphism, and inheritance give object-oriented programming a new kind of power that is hard for a traditional programmer to imagine.

An object-oriented language, no matter how well designed, is not of immediate benefit to its users unless a good object-library comes with it. The NextStep library is written in NeXT Inc.’s version of Objective-C; it goes far beyond the minimal library that come with commercial versions of Objective C for other computers. As a very rough estimate, I would say that NextStep has all the functionality of MacApp plus more features, but at a higher level of abstraction (with perhaps less freedom of customization). Not having used MacApp (I’ve only read about it), I can not comment further in this comparison.

The typical method of programming on the NeXT starts with Interface Builder. Starting a new project, you are given a default window with resize, miniaturize, and close controls, a default menu containing a few items, and a default panel for displaying copyright information. Interface Builder has a palette containing selections for additional defined and undefined menu items, panels and windows, and different kinds of controls: buttons, sliders, scrolling-fields, text-fields, etc. You can create custom versions of Interface Builder with additional palette objects. (Panels are windows that would be used as modal or modeless dialogs.) A menu item brings up a an inspector window, which can be used for managing the project’s files as well as textually modifying selected objects. Using Interface Builder is fairly easy for any Mac programmer already familiar with ResEdit, Prototyper, etc., though this program does not have the most straight-forward user-interface. It can be rather frustrating at first, and tedious as your skill grows.

Prototyper on the Macintosh allows linking buttons and menu items to dialogs and windows, to provide a minimal amount of control -- opening or closing windows and dialogs is about all you can do. Prototyper can also be used to generate an editable resource file and C or Pascal code for handling dialogs, windows, scroll bars (with some bugs in the version I used), menus, etc. You can then use that code as the framework for your own programming, and you can rewrite the code as needed. Interface Builder doesn’t work as a code generator in the same manner as Prototyper. It creates a “.nib” file for your project, which seems to hold the data required for the windows, menus, etc. No specifications for the format of the “.nib” have been published as far as I know. (I suspect that Interface Builder takes advantage of archiving methods implemented by all the AppKit classes.) During the link-step of compiling to an executable, data from the “.nib” is put into a mach-file-segment. Mach-file-segments may also hold the bitmap data from TIFF files to be used as icons and pictures in and for the application. The code generated by IB only contains instance variables that will refer to the objects you have used (menus, buttons, whatever), methods to initialize those instance variables, and a main program stub that creates the application-object, tells it to read in the data from the “.nib” segment, and starts it running. You can also write code to dynamically load in .nib files, allowing multiple instances of the same objects. In something almost approximating a SmallTalk browser, you can have Interface Builder generate the Objective-C declarations in a header file for a custom object class.

A major difference between Mac programs and NeXT programs is in the event-handling structure. On the Mac, you have a top-level routine (often the main program) that calls GetNextEvent or WaitNextEvent and branches through a switch or case statement to decide on which routine should handle the most recent event according to the current program state. On the NeXT, you normally create at least one custom object, often a subclass of View, which you link via interface builder to the user-interface objects. When you make the link, you specify what method the object should call in your custom object. If your custom object has not already inherited a definition for that method, then you have to write the code for that method. An example is linking a button named “Launch Rockets” to your custom-view, calling the method “rocketlaunch:sender”. Another example would be to link the menu item “Print” to your custom view, calling the inherited method “PrintPSCode”. The way events reach your code is kept behind the scenes: the application object gets events from the event-queue in a manner similar to the Macintosh, it also knows which windows it has and forwards appropriate events to those windows. The windows forward events to whatever internal objects they know about, and so on through the hierarchy of views and subviews of windows. Eventually an object receives an event that it knows how to handle, and it calls a method to perform the appropriate action. The only code you write are those methods to be called by the user-interface objects. The only time you need to write code for checking events is when you are doing animation, or tracing mouse movements in real time.

The source code example is an example of an Objective C program that could be expanded into an arcade game. The main program merely gets the ball rolling, so to speak -- the RocketView class is essentially the entire program. Note that the program is completely passive, it only responds to events, and in this case the events are the initial-window-exposed event, clicking in the launch-rockets button, and choosing Print from the main menu. If you want your program to do something in the absence of events, such as animating the missiles while waiting for other button-presses, you will have to create timer-events to start up and/or continue your animation-loop. The BreakApp example program that comes with the NeXT uses an “Animator” object that simplifies creation of these timer-events, and can also be used to check if a non-timer event has occurred.

Something that old-world (PC, mainframe) programmers may have a very difficult time understanding, is that methods are not separate processes. (You can write code C code to use multiple MACH threads, semaphores, etc., but that depends on operating-system calls not related to Objective-C.) You generally cannot have a method continuously executing and also have other methods respond to external events. Nor are methods like interrupt-routines. You cannot have a method which will be continued automatically after an another method interrupts it. It is possible to poll for events in the Macintosh fashion, and go through a switch or case statement for handling events, but then you can not use Interface Builder to link user-interface objects to call methods in your code, and you lose the other benefit of having the pseudo-resource-file that Interface Builder provides.

The compiler on the NeXT is the GNU C compiler, customized by NeXT to compile Objective-C directly instead of using a preprocessor. The debugger is GNU’s symbolic debugger “gdb”, which uses a command-line syntax and runs under the Shell. The debugger is about as powerful as the THINK C and THINK Pascal symbolic debuggers, though much more inconvenient. Because of the Free Software Foundation’s CopyLeft agreement, you can obtain the source code of the compiler, the debugger, and EMACS, with NeXT’s modifications, for $150 plus an magneto-optical disk.

All in all, the NeXT environment reflects the desire to provide a Macintosh-like interface without duplicating the Macintosh’s difficulty in programming. The goal of making NeXT programming easy to learn and powerful at the same time, has been met with the NextStep object library and Interface Builder. The downside, just like Apple, is that you have to follow the rules.

Next’s Application Kit, Sound Kit, and Music Kit, and Base Objective-C object classes, in alphabetical order with inheritances listed -- all are ultimately descended from Object.

ActionCell : Cell
Application : Responder
Bitmap
Box : View  : Responder
Button : Control : View  : Responder
ButtonCell : ActionCell : Cell
Cell
ChoosePrinter : Panel : Window : Responder
ClipView : View : Responder
Conductor
Control : View  : Responder
Cursor : Bitmap
Envelope
FilePerformer : Performer
FileWriter : Instrument
Font
FontManager
FontPanel  : Panel : Window : Responder
Form : Matrix  : Control : View  : Responder
FormCell : ActionCell : Cell
HashTable
Instrument
List
Listener
Matrix  : Control : View  : Responder
Menu  : Panel : Window : Responder
MenuCell : ButtonCell : ActionCell : Cell
Midi
Note
NoteFilter : Instrument
NoteReceiver
NoteSender
Object (root class)
OpenPanel : SavePanel  : Panel : Window : Responder
Orchestra
PageLayout  : Panel : Window : Responder
Panel : Window : Responder
Part
Partials : WaveTable
PartPerformer : Performer
PartRecorder : Instrument
Pasteboard
PatchTemplate 
Performer
PopUpList : Menu  : Panel : Window : Responder
PrintInfo
PrintPanel  : Panel : Window : Responder
Responder
Samples : WaveTable
SavePanel  : Panel : Window : Responder
Score
ScoreFilePerformer : Fileperformer : Performer 
ScoreFileWriter : FileWriter : Instrument
ScorePerformer
ScoreRecorder
Scroller  : Control : View  : Responder
ScrollView : View  : Responder
SelectionCell : Cell
Slider  : Control : View  : Responder
SliderCell : ActionCell : Cell
Sound
SoundMeter : View : Responder 
SoundView : VIew : Responder
Speaker
Storage
StreamTable : HashTable
SynthData
SynthInstrument : Instrument
SynthPatch
Text : View  : Responder
TextField  : Control : View  : Responder
TextFieldCell : ActionCell : Cell
TuningSystem
UnitGenerator
View  : Responder
WaveTable
Window : Responder
program file RocketApp.m

/* The main program ( RocketApp_main.m ) */

#include <appkit/appkit.h>
#include <stdio.h>

int main(int argc, char * argv[])
{
 id app;

 app = [ Application new ];
 [ app loadFromNibFile: “RocketApp.nib” ];
 [ app run ];  /* this loops until Quit selected. */
 [ app free ];

 exit( 0 );
}
-- the header file RocketView.h --

/* FILE = RocketView.h */

#import <appkit/appkit.h>

#define MAXMISSLES 5

@interface  RocketView : View 
/* subclass of view */
{
 /* all instance variables are private by default. */

 NXPointmisslePositions[MAXMISSLES];
 BOOL   misslesLaunched;
 int    numRockets;

 /* we could have created an array of missle objects and allowed more 
flexibility in modifying this program later... */

 idBlaunchRockets; 
 /* launch rocket button */

 idIFnumberRockets; 
 /* input text field = a Form object */
}

+ newFrame: (const NXRect *) frameRect;
 /* override View’s default newFrame method - this is a “factory method” 
for creating instances of the class. */

- updatedrawing;
 /* draws the missles in the view -- an “instance method” */

- drawSelf: (const NXRect *) rects : (int) rectCount;
 /* override View’s default drawing method -- we don’t call this directly. 
 “drawSelf::” gets called when the window/view objects are first displayed, 
and at certain other times, such as in response to the “printPSCode:” 
message.  By properly defining this routine, the program can automatically 
support printing as well as displaying -- so long as you don’t use certain 
Display PostScript extensions, such as compositing bitmaps! */

- setBlaunchRockers:anObject;
 /* created by interface builder */

- setIFnumberRockets:anObject;
 /* created by interface builder */

/* “setBlaunchRockers:” and “setIFnumberRockets:” are required by Interface 
Builder and the application object’s “loadNibFile:” methods -- these 
link the button and form objects specified in Interface Builder with 
the id-variables used in your code. */

- rocketlaunch:sender;

/* in this program, the sender will always be the button named “Launch 
Rockets” and this routine will be called when the user clicks in this 
button object during execution of this program */

@end
-- program file RocketView.m --

/* FILE = RocketView.m */

#import <appkit/appkit.h>
#import “rocketview.h”

@implementation  RocketView : View
{
 /* repeating the instance-variables part of the object declaration is 
not required by the syntax, but it is permitted and checked to match 
the interface declaration, and I think it is a good idea for documentation 
purposes. */

 NXPointmisslePositions[MAXMISSLES];
 BOOL   misslesLaunched;
 int    numRockets;

 idBlaunchRockets; 
 /* launch rocket button */

 idIFnumberRockets; 
 /* input text field = a Form object */
}

+ newFrame: (const NXRect *) frameRect
 /* override View’s default newFrame method */
{
 int i;

 self = [ super newFrame: frameRect ]; 

/* change self to point to the newly created object-instance, instead 
of pointing to the rocketView Factory object. */

 numRockets = 0;
 for ( i = 0; i < MAXMISSLES ; i++ )
 {
 misslePositions[i].x = (1+i) * 10;
 misslePositions[i].y = 10.0;
 }
 misslesLaunched = NO;

 [self setFlip: NO]; 
 /* keep 0,0 at lower left corner of view */
 
 [self allocateGstate];
 return self; 
}

- updatedrawing
 /* draws the missles in the view */
{
 int i;

 [self lockFocus ];

 if ( misslesLaunched )
 {
 for (i = 0; i < numRockets - 1; i++ )
 { 
 /* draw Very simple missles -- 
 not even animated! */
 PSmoveto( misslePositions[i].x, misslePositions[i].y );
 PSlineto( misslePositions[i].x, misslePositions[i].y + 10.0 );
 PSstroke();
 }
 }
 NXPing(); 

 /* NXPing forces the window manager to update the view on screen -- 
flushes the postscript pipeline */

 [self unlockFocus];

 return self; 

 /* if nothing else, tradition says return self */
}

- drawSelf: (const NXRect *) rects : (int) rectCount
 /* override View’s default drawing method */
{
 /* ignore the rectangles which could be used for limiting the amount 
of drawing required. */

 [ self updatedrawing ];
 return self;
}

- setBlaunchRockers:anObject
 /* created by interface builder */
{
 BlaunchRockers = anObject;
 return self;
}

- setIFnumberRockets:anObject
 /* created by interface builder */
{
 IFnumberRockets = anObject;
 return self;
}

- rocketlaunch:sender
 /* in this program, this sender will always be the button named “Launch 
Rockets” and this routine will be called when the user clicks in this 
button object during execution of this program */
{
 int i;

 if ( ! misslesLaunched )
 {
 misslesLaunched = YES;
 i = [ IFnumberRockets intValueAt: 0 ];

 /* get the number of rockets from the string contained in the Form. 
 We specified an initial default value with Interface Builder; at any 
time before pushing the button, the user could change the text to any 
string.  If an integer can not be parsed from the string, we get zero 
as the value. */
 
 if ( i <= MAXMISSLES )
 {
 numRockets = i;
 }
 }
 else
 {
 NXBeep();
 }
 [ self updatedrawing ];
}

@end

List of trademarks

NeXT, NextStep, Interface Builder, Application Kit, Music Kit, and Sound Kit are a trademarks of NeXT, Inc.

Display PostScipt, and PostScript are trademarks of Adobe, Inc.

Unix is a trademark of AT&T.

GDB, GNU C, and GNUemacs, are trademarks of the Free Software Foundation.

Prototyper is a trademark of Smethers-Barns.

Macintosh is a trademark licensed to Apple Computer, Inc.

MacApp is a trademark of Apple Computer, Inc.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

SpamSieve 2.9.38 - Robust spam filter fo...
SpamSieve is a robust spam filter for major email clients that uses powerful Bayesian spam filtering. SpamSieve understands what your spam looks like in order to block it all, but also learns what... Read more
TeamViewer 15.0.8397 - Establish remote...
TeamViewer gives you remote control of any computer or Mac over the Internet within seconds or can be used for online meetings. Find out why more than 200 million users trust TeamViewer! Free for non... Read more
SteerMouse 5.4.3 - Powerful third-party...
SteerMouse is an advanced driver for USB and Bluetooth mice. SteerMouse can assign various functions to buttons that Apple's software does not allow, including double-clicks, modifier clicks,... Read more
Toast Titanium 18.2.1 - The ultimate med...
Roxio Toast Titanium, the leading DVD burner for Mac, makes burning even better, adding Roxio Secure Burn to protect your files on disc and USB in Mac- or Windows-compatible formats. Get more style... Read more
HoudahSpot 5.0.11 - Advanced file-search...
HoudahSpot is a versatile desktop search tool. Use HoudahSpot to locate hard-to-find files and keep frequently used files within reach. HoudahSpot will immediately feel familiar. It works just the... Read more
ClipGrab 3.8.6 - Download videos from Yo...
ClipGrab is a free downloader and converter for YouTube, Vimeo, Facebook and many other online video sites. It converts downloaded videos to MPEG4, MP3 or other formats in just one easy step Version... Read more
ExpanDrive 7.4.0 - Access cloud storage...
ExpanDrive builds cloud storage in every application, acts just like a USB drive plugged into your Mac. With ExpanDrive, you can securely access any remote file server directly from the Finder or... Read more
Adobe Dreamweaver CC 2020 20.0 - Build w...
Dreamweaver CC 2020 is available as part of Adobe Creative Cloud for as little as $20.99/month (or $9.99/month if you're a previous Dreamweaver customer). Adobe Dreamweaver CC 2020 allows you to... Read more
Eye Candy 7.2.3.85 - 30 professional Pho...
Eye Candy renders realistic effects that are difficult or impossible to achieve in Photoshop alone, such as Fire, Chrome, and the new Lightning. Effects like Animal Fur, Smoke, and Reptile Skin are... Read more
Sparkle Pro 2.8.5 - Visual website creat...
Sparkle Pro will change your mind if you thought building websites wasn't for you. Sparkle is the intuitive site builder that lets you create sites for your online portfolio, team or band pages, or... Read more

Latest Forum Discussions

See All

Pre-register for Hello Kitty AR: Kawaii...
Hello Kitty — the cute cat that launched a multi-billion-pound franchise — has been brought to life… sort of. Sanrio has teamed up with the Bublar Group to create a new mobile game that uses AR tech to turn the real world into Hello Kitty’s... | Read more »
Gorgeous and tranquil puzzler Spring Fal...
One-man indie studio SPARSE//GameDev has now launched its tranquil puzzler, Spring Falls. It's described as "a peaceful puzzle game about water, erosion, and watching things grow". [Read more] | Read more »
Black Desert Mobile gets an official rel...
Pearl Abyss has just announced that its highly-anticipated MMO, Black Desert Mobile, will launch globally for iOS and Android on December 11th. [Read more] | Read more »
Another Eden receives new a episode, cha...
Another Eden, WFS' popular RPG, has received another update that brings new story content to the game alongside a few new heroes to discover. [Read more] | Read more »
Overdox guide - Tips and tricks for begi...
Overdox is a clever battle royale that changes things up by adding MOBA mechanics and melee combat to the mix. This new hybrid game can be quite a bit to take in at first, so we’ve put together a list of tips to help you get a leg up on the... | Read more »
Roterra Extreme - Great Escape is a pers...
Roterra Extreme – Great Escape has been described by developers Dig-It Games as a mini-sequel to their acclaimed title Roterra: Flip the Fairytale. It continues that game's tradition of messing with which way is up, tasking you with solving... | Read more »
Hearthstone: Battlegrounds open beta lau...
Remember earlier this year when auto battlers were the latest hotness? We had Auto Chess, DOTA Underlords, Chess Rush, and more all gunning for our attention. They all had their own reasons to play, but, at least from where I'm standing, most... | Read more »
The House of Da Vinci 2 gets a new gamep...
The House of Da Vinci launched all the way back in 2017. Now, developer Blue Brain Games is gearing up to deliver a second dose of The Room-inspired puzzling. Some fresh details have now emerged, alongside the game's first official trailer. [Read... | Read more »
Shoot 'em up action awaits in Battl...
BattleBrew Productions has just introduced another entry into its award winning, barrelpunk inspired, BattleSky Brigade series. Whilst its previous title BattleSky Brigade TapTap provided fans with idle town building gameplay, this time the... | Read more »
Arcade classic R-Type Dimensions EX blas...
If you're a long time fan of shmups and have been looking for something to play lately, Tozai Games may have just released an ideal game for you on iOS. R-Type Dimensions EX brings the first R-Type and its sequel to iOS devices. [Read more] | Read more »

Price Scanner via MacPrices.net

13″ 2.4GHz MacBook Pros available for up to $...
Apple has a full line of Certified Refurbished 2019 13″ 2.4GHz 4-Core Touch Bar MacBook Pros available starting at $1529 and up to $300 off MSRP. Apple’s one-year warranty is included, shipping is... Read more
New at T-Mobile: Switch to T-Mobile, and get...
T-Mobile is offering a free 64GB iPhone 8 for new customers who switch to T-Mobile and open a new line of service. Eligible trade-in required, and discount applied over a 24 month period. The fine... Read more
Xfinity Mobile’s Black Friday Apple savings:...
Take $250 off the purchase of any iPhone at Xfinity Mobile with a new line activation, and transfer of phone number to Xfinity Mobile, through December 8, 2019. This includes Apple’s new iPhone 11... Read more
2019 13″ 1.4GHz MacBook Pros available starti...
Apple has a full line of Certified Refurbished 2019 13″ 1.4GHz 4-Core Touch Bar MacBook Pros available starting at $1099 and up to $230 off MSRP. Apple’s one-year warranty is included, shipping is... Read more
Save up to $350 on a 21″ or 27″ iMac with the...
Apple has Certified Refurbished 2019 21″ & 27″ iMacs available starting at $929 and up to $350 off the cost of new models. Apple’s one-year warranty is standard, shipping is free, and each iMac... Read more
Early Holiday 2019 Sale: B&H again offers...
B&H Photo has 10.2″ iPads on sale again for $30 off Apple’s MSRP, starting at $299, as part of their early Holiday 2019 sale. Overnight shipping is free to many addresses in the US: – 10.2″ 32GB... Read more
Apple iMacs on sale today at B&H Photo fo...
B&H Photo has new 2019 21″ and 27″ 5K iMacs on stock today and on sale for up to $150 off Apple’s MSRP. Overnight shipping is free to many locations in the US. These are the same iMacs sold by... Read more
2018 4 and 6-Core Mac minis on sale today for...
Apple resellers are offering new 2018 4-Core and 6-Core Mac minis for $80-$100 off MSRP for a limited time. B&H Photo has the new 2018 4-Core and 6-Core Mac minis on sale for up to $100 off Apple... Read more
Early Holiday 2019 sale at B&H Photo: 12....
B&H Photo has new 12.9″ iPad Pros on sale for up to $120 off Apple’s MSRP as part of their early Holiday 2019 sale. Overnight shipping is free to many addresses in the US: – 12.9″ 64GB WiFi iPad... Read more
8-Core iMac Pro on sale today for $4499 at B...
B&H Photo has the base 8-Core 3.2GHz 32GB/1TB iMac Pro on sale today for $4499 — $500 off Apple’s MSRP. Shipping is free. Their price is the lowest available for a new iMac Pro from any Apple... Read more

Jobs Board

*Apple* Health Benefit Specialist - Call Cen...
Description ** Apple Health Benefit Specialist - Call Center (MAS 3/MACSC)** **Olympia, WA Multiple Positions** *The ideal candidate for this position will have Read more
Hair Stylist - *Apple* Blossom Mall - JCPen...
Hair Stylist - Apple Blossom Mall Location:Winchester, VA, United States- Apple Blossom Mall 1850 Apple Blossom Dr Job ID:1065040Salon Professionals Job Read more
*Apple* Mobility Pro - Best Buy (United Stat...
**747088BR** **Job Title:** Apple Mobility Pro **Job Category:** Store Associates **Store NUmber or Department:** 000297-Reston-Store **Job Description:** At Best Read more
Nurse Practitioner - Field Based (San Bernard...
Nurse Practitioner - Field Based (San Bernardino, CA, Apple Valley, Hesperia) **Location:** **United States** **Requisition #:** PS30312 **Post Date:** Nov 11, 2019 Read more
Best Buy *Apple* Computing Master - Best Bu...
**747061BR** **Job Title:** Best Buy Apple Computing Master **Job Category:** Store Associates **Store NUmber or Department:** 000647-Kildeer-Store **Job Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.