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

Posterino 3.3.5 - Create posters, collag...
Posterino offers enhanced customization and flexibility including a variety of new, stylish templates featuring grids of identical or odd-sized image boxes. You can customize the size and shape of... Read more
Kodi 17.1. - Powerful media center tool...
Kodi (was XBMC) is an award-winning free and open-source (GPL) software media player and entertainment hub that can be installed on Linux, OS X, Windows, iOS, and Android, featuring a 10-foot user... Read more
Kodi 17.1. - Powerful media center tool...
Kodi (was XBMC) is an award-winning free and open-source (GPL) software media player and entertainment hub that can be installed on Linux, OS X, Windows, iOS, and Android, featuring a 10-foot user... Read more
Bookends 12.8 - Reference management and...
Bookends is a full-featured bibliography/reference and information-management system for students and professionals. Bookends uses the cloud to sync reference libraries on all the Macs you use.... Read more
Apple iTunes 12.6 - Play Apple Music and...
Apple iTunes lets you organize and stream Apple Music, download and watch video and listen to Podcasts. It can automatically download new music, app, and book purchases across all your devices and... Read more
Default Folder X 5.1.4 - Enhances Open a...
Default Folder X attaches a toolbar to the right side of the Open and Save dialogs in any OS X-native application. The toolbar gives you fast access to various folders and commands. You just click on... Read more
Amazon Chime 4.1.5587 - Amazon-based com...
Amazon Chime is a communications service that transforms online meetings with a secure, easy-to-use application that you can trust. Amazon Chime works seamlessly across your devices so that you can... Read more
CrossOver 16.2 - Run Windows apps on you...
CrossOver can get your Windows productivity applications and PC games up and running on your Mac quickly and easily. CrossOver runs the Windows software that you need on Mac at home, in the office,... Read more
Adobe Creative Cloud 4.0.0.185 - Access...
Adobe Creative Cloud costs $19.99/month for a single app, or $49.99/month for the entire suite. Introducing Adobe Creative Cloud desktop applications, including Adobe Photoshop CC and Illustrator CC... Read more
MegaSeg 6.0.2 - Professional DJ and radi...
MegaSeg is a complete solution for pro audio/video DJ mixing, radio automation, and music scheduling with rock-solid performance and an easy-to-use design. Mix with visual waveforms and Magic... Read more

The best deals on the App Store this wee...
Deals, deals, deals. We're all about a good bargain here on 148Apps, and luckily this was another fine week in App Store discounts. There's a big board game sale happening right now, and a few fine indies are still discounted through the weekend.... | Read more »
The best new games we played this week
It's been quite the week, but now that all of that business is out of the way, it's time to hunker down with some of the excellent games that were released over the past few days. There's a fair few to help you relax in your down time or if you're... | Read more »
Orphan Black: The Game (Games)
Orphan Black: The Game 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: Dive into a dark and twisted puzzle-adventure that retells the pivotal events of Orphan Black. | Read more »
The Elder Scrolls: Legends is now availa...
| Read more »
Ticket to Earth beginner's guide: H...
Robot Circus launched Ticket to Earth as part of the App Store's indie games event last week. If you're not quite digging the space operatics Mass Effect: Andromeda is serving up, you'll be pleased to know that there's a surprising alternative on... | Read more »
Leap to victory in Nexx Studios new plat...
You’re always a hop, skip, and a jump away from a fiery death in Temple Jump, a new platformer-cum-endless runner from Nexx Studio. It’s out now on both iOS and Android if you’re an adventurer seeking treasure in a crumbling, pixel-laden temple. | Read more »
Failbetter Games details changes coming...
Sunless Sea, Failbetter Games' dark and gloomy sea explorer, sets sail for the iPad tomorrow. Ahead of the game's launch, Failbetter took to Twitter to discuss what will be different in the mobile version of the game. Many of the changes make... | Read more »
Splish, splash! The Pokémon GO Water Fes...
Niantic is back with a new festival for dedicated Pokémon GO collectors. The Water Festival officially kicks off today at 1 P.M. PDT and runs through March 29. Magikarp, Squirtle, Totodile, and their assorted evolved forms will be appearing at... | Read more »
Death Road to Canada (Games)
Death Road to Canada 1.0 Device: iOS Universal Category: Games Price: $7.99, Version: 1.0 (iTunes) Description: Get it now at the low launch price! Price will go up a dollar every major update. Update news at the bottom of this... | Read more »
Bean's Quest Beginner's Guide:...
Bean's Quest is a new take on both the classic platformer and the endless runner, and it's free on the App Store for the time being. Instead of running constantly, you can't stop jumping. That adds a surprising new level of challenge to the game... | Read more »

Price Scanner via MacPrices.net

Updated iPad Price Trackers
Scan our Apple iPad (and iPod touch) Price Trackers for the latest information on sales, bundles, and availability on systems from Apple’s authorized internet/catalog resellers. We update the... Read more
12-inch 32GB Space Gray iPad Pro on sale for...
B&H Photo has 12″ Space Gray 32GB WiFi Apple iPad Pros on sale for $50 off MSRP including free shipping. B&H charges sales tax in NY only: - 12″ Space Gray 32GB WiFi iPad Pro: $749 $50 off... Read more
2.6GHz Mac mini on sale for $559, $140 off MS...
Guitar Center has the 2.6GHz Mac mini (MGEN2LL/A) on sale for $559 including free shipping. Their price is $140 off MSRP, and it’s the lowest price available for this model. Read more
SSD Speeder RAM Disk SSD Life Extender App Fo...
Fehraltorf, Switzerland based B-Eng has announced they are making their SSD Speeder app for macOS publicly available for purchase on their website. SSD Speeder is a RAM disk utility that prevents... Read more
iPhone Scores Highest Overall in Smartphone D...
Customer satisfaction is much higher among smartphone owners who use their device to operate other connected home services such as smart thermostats and smart appliances, according to the J.D. Power... Read more
Swipe CRM Free Photo-Centric CRM Sales DEal C...
Swipe CRM LLC has introduced Swipe CRM: Visual Sales 1.0 for iPad, an app for creating, managing, and sharing visually stunning sales deals. Swipe CRM is targeted to small-and-medium creative... Read more
13-inch 2.0GHz Apple MacBook Pros on sale for...
B&H has the non-Touch Bar 13″ 2.0GHz MacBook Pros in stock today and on sale for $150 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 13″ 2.0GHz MacBook Pro Space Gray (... Read more
15-inch Touch Bar MacBook Pros on sale for up...
B&H Photo has the new 2016 15″ Apple Touch Bar MacBook Pros in stock today and on sale for up to $150 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 15″ 2.7GHz Touch Bar... Read more
Apple’s iPhone 6s Tops Best-Selling Smartphon...
In terms of shipments, the iPhone 6s from Apple bested all competitors for sales in 2016, according to new analysis from IHS Markit, a world leader in critical information, analytics and solutions.... Read more
Logitech Rugged Combo Protective iPad Case an...
Logitech has announced its Logitech Rugged Combo, Logitech Rugged Case, and Logitech Add-on Keyboard for Rugged Case for Apple’s new, more affordable $329 9.7-inch iPad, a complete solution designed... Read more

Jobs Board

*Apple* Mobile Master - Best Buy (United Sta...
**492889BR** **Job Title:** Apple Mobile Master **Location Number:** 000886-Norwalk-Store **Job Description:** **What does a Best Buy Apple Mobile Master do?** Read more
*Apple* Mobile Master - Best Buy (United Sta...
**492472BR** **Job Title:** Apple Mobile Master **Location Number:** 000470-Seattle-Store **Job Description:** **What does a Best Buy Apple Mobile Master do?** Read more
*Apple* Mobile Master - Best Buy (United Sta...
**492562BR** **Job Title:** Apple Mobile Master **Location Number:** 000853-Jackson-Store **Job Description:** **What does a Best Buy Apple Mobile Master do?** Read more
*Apple* Retail - Multiple Positions - Apple,...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
Fulltime aan de slag als shopmanager in een h...
Ben jij helemaal gek van Apple -producten en vind je het helemaal super om fulltime shopmanager te zijn in een jonge en hippe elektronicazaak? Wil jij werken in Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.