TweetFollow Us on Twitter

May 95 Tips
Volume Number:11
Issue Number:5
Column Tag:Tips & Tidbits

Tips & Tidbits

By Scott T Boyd, Editor

Note: Source code files accompanying article are located on MacTech CD-ROM or source code disks.


Flush Out Your Bugs

Before releasing an application to your testers, load these three extensions: EBBE (Even Better Bus Error), DisposeResource, and DoubleTrouble. They check for NIL dereferences, improperly-disposed resources, and multiply-disposed memory manager blocks. [You can find these extensions in many places, including our ftp and other online sites - Ed stb] Run your application. You may be surpised at what you find.

Using these debugging tools, I caught a bug in an application based on the 1/18/95 release of Sprocket. This bug was fixed in the 1/25/95 Sprocket release, and does not exist in the 12/94 release. I’m using this code both as an example and a suggested patch if you are using the 1/18 version of Sprocket.

        if (fSplashPicture)
                DisposeHandle((Handle) fSplashPicture);  // Oops!

        WindowPtr       newFrontWindow = nil;
        if (FrontNonFloatingWindow() == fWindow)
          newFrontWindow = (WindowPtr)((WindowPeek)fWindow)->nextWindow;
        if (newFrontWindow)
        return true;

When I ran the executable, I dropped into my low level debugger, and looked at the stack. Return addresses on the stack from the MacsBug stack crawl sc7:

  Stack Addr  Frame Addr   Caller
   01C6ECD0               01B6D6D2 'CODE 0001 2690 Sprocket Lib'+0172
   01C6ECC8               01B6D692 'CODE 0001 2690 Sprocket Lib'+0132
   01C6ECAA    01C6ECA6   01B6E9F8 main+01F2
   01C6EC9E    01C6EC9A   01B6EF7A TSplashWindow::~TSplashWindow()+002C
   01C6EC88               01B6FA3C TWindow::Close()+0034
   01C6EC80    01C6EC7C   408578C4 _DisposeWindow+0004
   01C6EC6C               4085A846 _FrontWindow+0096
   01C6EC54               40877EB4 _KillPicture+0004
   01C6EC40               4085785C _NewWindow+010C
   01C6EC34               40877EB4 _KillPicture+0004
   01C6EC30               4085785C _NewWindow+010C

From this stack trace I saw that fSplashPicture got disposed again by DisposeWindow(fWindow); A review of the code showed the offending extra Dispose in ~TSplashWindow().

Why not leave these debugging resources on your system all the time? Well, it appears that not everyone uses these tools religiously and several other of my favorite (nameless) applications write to location Zero and trigger EBBE. I’ve sent in bug reports to the offenders, but I am still waiting for all the update releases.

Happy Bug Trails!

- Gary W. Powell

Powering Up The RTM Instruction

For you power programmers out there, here’s a little tip on taking advantage of the PowerPC architecture. Where you might have used the 68020 RTM instruction (Return from Module), you can get a lot of mileage by using the new PowerPC RTFM instruction instead. We can assure you that you will save literally hours of time.

- David Gorkan and Allan Foster

Save a Little Time

Here is a great and easy way to supercharge File Open... File Save and File Save As... operations from any application, especially if you use the Apple Menu Items to store aliases to folders: Make an alias of the Apple Menu Items folder and put it on the Desktop.

What does that get you? Well, since the Standard file Get and Put Dialogs all have a Desktop button, you can easily get to the Apple Menu Items, and hence access any aliases that are stored there. Just Click on the Desktop folder and the Apple Menu Item Alias appears as a supercharged Volume of Aliases.

But wait, there’s more! You get a real bonus from using System 7.5 because, if you put the Apple Menu Items alias onto the desktop, System 7.5 maintains automated folders, so the Apple Menu Items Alias can be used to get to “Recent Documents”. The “Recent Servers” can be used to log onto to any server without leaving the application that you are running.

- Mark Tillinghast
XXCAL, Testing And Systems Division

Debugging For Fun and Profit

When you have routines that return OSErrs, finish them with the following bit of code:

ReportError ( err );
return err;

which is defined as:

#ifdef qDEBUG
#define ReportError(err) do { if (err != noErr ) DebugStr ( “
\pError” ); } while (false)
#define ReportError(err)  /* nothing */

With this macro, you can tell every time that one of your routines returns an error, and it’s easy to follow your error handling code.

- Marshall Clow
Aladdin Systems

What’s My Modifier?

To quickly get the status of modifier keys, use these simple lines:

typedef struct kbd_bits {
 int command : 1;
 int : 5;
 int space : 1;
 int tab : 1;
 int : 4;
 control : 1;
 option : 1;
 capslock : 1;
 shift : 1;
} kbd_bits;

#define KeyModifiers (*(kbd_bits *)0x17A)

Then you can say simply:

if (KeyModifiers.control) {
 Debugger(); // drop into a debugger

This works across all Macs, including foreign versions and keyboard maps. For maximum compatibility with a minimal speed hit, call GetOSEvent with a null event mask and examine the modifiers field of the event returned.

- Jorg Brown
The Mac Group


Community Search:
MacTech Search:

Software Updates via MacUpdate

Microsoft Office 2016 16.11 - Popular pr...
Microsoft Office 2016 - Unmistakably Office, designed for Mac. The new versions of Word, Excel, PowerPoint, Outlook, and OneNote provide the best of both worlds for Mac users - the familiar Office... Read more
Adobe Photoshop CC 2018 19.1.2 - Profess...
Photoshop CC 2018 is available as part of Adobe Creative Cloud for as little as $19.99/month (or $9.99/month if you're a previous Photoshop customer). Adobe Photoshop CC 2018, the industry standard... Read more
Adobe Dreamweaver CC 2018 -...
Dreamweaver CC 2018 is available as part of Adobe Creative Cloud for as little as $19.99/month (or $9.99/month if you're a previous Dreamweaver customer). Adobe Dreamweaver CC 2018 allows you to... Read more
Adobe Flash Player - Plug-in...
Adobe Flash Player is a cross-platform, browser-based application runtime that provides uncompromised viewing of expressive applications, content, and videos across browsers and operating systems.... Read more
Drive Genius 5.2.0 - $79.00
Drive Genius features a comprehensive Malware Scan. Automate your malware protection. Protect your investment from any threat. The Malware Scan is part of the automated DrivePulse utility. DrivePulse... Read more
MegaSeg 6.0.6 - 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
ffWorks 1.0.7 - Convert multimedia files...
ffWorks (was iFFmpeg), focused on simplicity, brings a fresh approach to the use of FFmpeg, allowing you to create ultra-high-quality movies without the need to write a single line of code on the... Read more
Dash 4.1.5 - Instant search and offline...
Dash is an API documentation browser and code snippet manager. Dash helps you store snippets of code, as well as instantly search and browse documentation for almost any API you might use (for a full... Read more
Evernote 7.0.3 - Create searchable notes...
Evernote allows you to easily capture information in any environment using whatever device or platform you find most convenient, and makes this information accessible and searchable at anytime, from... Read more
jAlbum Pro 15.3 - Organize your digital...
jAlbum Pro has all the features you love in jAlbum, but comes with a commercial license. You can create gorgeous custom photo galleries for the Web without writing a line of code! Beginner-friendly... Read more

Latest Forum Discussions

See All

Around the Empire: What have you missed...
Oh hi nice reader, and thanks for popping in to check out our weekly round-up of all the stuff that you might have missed across the Steel Media network. Yeah, that's right, it's a big ol' network. Obviously 148Apps is the best, but there are some... | Read more »
All the best games on sale for iPhone an...
It might not have been the greatest week for new releases on the App Store, but don't let that get you down, because there are some truly incredible games on sale for iPhone and iPad right now. Seriously, you could buy anything on this list and I... | Read more »
Everything You Need to Know About The Fo...
In just over a week, Epic Games has made a flurry of announcements. First, they revealed that Fortnite—their ultra-popular PUBG competitor—is coming to mobile. This was followed by brief sign-up period for interested beta testers before sending out... | Read more »
The best games that came out for iPhone...
It's not been the best week for games on the App Store. There are a few decent ones here and there, but nothing that's really going to make you throw down what you're doing and run to the nearest WiFi hotspot in order to download it. That's not to... | Read more »
Death Coming (Games)
Death Coming Device: iOS Universal Category: Games Price: $1.99, Version: (iTunes) Description: --- Background Story ---You Died. Pure and simple, but death was not the end. You have become an agent of Death: a... | Read more »
Hints, tips, and tricks for Empires and...
Empires and Puzzles is a slick match-stuff RPG that mixes in a bunch of city-building aspects to keep things fresh. And it's currently the Game of the Day over on the App Store. So, if you're picking it up for the first time today, we thought it'd... | Read more »
What You Need to Know About Sam Barlow’s...
Sam Barlow’s follow up to Her Story is #WarGames, an interactive video series that reimagines the 1983 film WarGames in a more present day context. It’s not exactly a game, but it’s definitely still interesting. Here are the top things you should... | Read more »
Pixel Plex Guide - How to Build Better T...
Pixel Plex is the latest city builder that has come to the App Store, and it takes a pretty different tact than the ones that came before it. Instead of being in charge of your own city by yourself, you have to work together with other players to... | Read more »
Fortnite Will Be Better Than PUBG on Mob...
Before last week, if you asked me which game I prefer between Fortnite Battle Royale and PlayerUnknown’s Battlegrounds (PUBG), I’d choose the latter just about 100% of the time. Now that we know that both games are primed to hit our mobile screens... | Read more »
Siege of Dragonspear (Games)
Siege of Dragonspear 2.5.12 Device: iOS Universal Category: Games Price: $9.99, Version: 2.5.12 (iTunes) Description: Experience the Siege of Dragonspear, an epic Baldur’s Gate tale, filled with with intrigue, magic, and monsters.... | Read more »

Price Scanner via

Sunday Sales: $200 off 13″ Touch Bar MacBook...
Amazon has new 2017 13″ 3.1GHz Touch Bar MacBook Pros on sale this weekend for $200 off MSRP, each including free shipping: – 13″ 3.1GHz/256GB Space Gray MacBook Pro (MPXV2LL/A): $1599.99 $200 off... Read more
B&H drops prices on 15″ MacBook Pros up t...
B&H Photo has dropped prices on new 2017 15″ MacBook Pros, now up to $300 off MSRP and matching Adorama’s price drop yesterday. Shipping is free, and B&H charges sales tax for NY & NJ... Read more
Apple restocks Certified Refurbished 2017 13″...
Apple has restocked Certified Refurbished 2017 13″ 2.3GHz MacBook Pros for $200-$230 off MSRP. A standard Apple one-year warranty is included with each MacBook, models receive new outer cases, and... Read more
13″ Space Gray Touch Bar MacBook Pros on sale...
Adorama has new 2017 13″ Space Gray Touch Bar MacBook Pros on sale for $150 off MSRP. Shipping is free, and Adorama charges sales tax in NY & NJ only: – 13″ 3.1GHz/256GB Space Gray MacBook Pro (... Read more
Best deal of the year on 15″ Apple MacBook Pr...
Adorama has New 2017 15″ MacBook Pros on sale for up to $300 off MSRP. Shipping is free, and Adorama charges sales tax in NJ and NY only: – 15″ 2.8GHz Touch Bar MacBook Pro Space Gray (MPTR2LL/A): $... Read more
Save $100-$150+ on 13″ Touch Bar MacBook Pros...
B&H Photo has 13″ Touch Bar MacBook Pros on sale for $100-$150 off MSRP. Shipping is free, and B&H charges sales tax for NY & NJ residents only: – 13″ 3.1GHz/256GB Space Gray MacBook Pro... Read more
Current deals on 27″ Apple iMacs, models up t...
B&H Photo has 27″ iMacs on sale for up to $150 off MSRP. Shipping is free, and B&H charges sales tax for NY & NJ residents only: – 27″ 3.8GHz iMac (MNED2LL/A): $2149 $150 off MSRP – 27″ 3... Read more
Thursday Deal: 13″ 2.3GHz MacBook Pro for $11...
B&H Photo has the 13″ 2.3GHz/128GB Space Gray MacBook Pro on sale for $100 off MSRP. Shipping is free, and B&H charges sales tax for NY & NJ residents only: – 13-inch 2.3GHz/128GB Space... Read more
How to save $100-$190 on 10″ & 12″ iPad P...
Apple is now offering Certified Refurbished 2017 10″ and 12″ iPad Pros for $100-$190 off MSRP, depending on the model. An Apple one-year warranty is included with each model, and shipping is free: –... Read more
Silver 12″ 1.3GHz MacBook on sale at B&H...
B&H Photo has the 2017 12″ 1.3GHz Silver MacBook on sale for $1399.99 including free shipping plus sales tax for NY & NJ residents only. Their price is $200 off MSRP, and it’s the lowest... Read more

Jobs Board

Firmware Engineer - *Apple* Accessories - A...
# Firmware Engineer - Apple Accessories Job Number: 113452350 Santa Clara Valley, California, United States Posted: 28-Feb-2018 Weekly Hours: 40.00 **Job Summary** Read more
Automation and Performance Engineer, *Apple*...
# Automation and Performance Engineer, Apple Pay Job Number: 113557967 Santa Clara Valley, California, United States Posted: 09-Mar-2018 Weekly Hours: 40.00 **Job Read more
Hardware Systems Architect - *Apple* Watch...
# Hardware Systems Architect - Apple Watch Job Number: 113565323 Santa Clara Valley, California, United States Posted: 05-Mar-2018 Weekly Hours: 40.00 **Job Read more
Lead *Apple* Solution Consultant - Apple (U...
# Lead Apple Solution Consultant Chicago IL Job Number: 113560644 Chicago, Illinois, United States Posted: 10-Mar-2018 Weekly Hours: 40.00 **Job Summary** As a Lead Read more
Art Director, *Apple* Music + Beats1 Market...
# Art Director, Apple Music + Beats1 Marketing Design Job Number: 113258081 Culver City, California, United States Posted: 07-Mar-2018 Weekly Hours: 40.00 **Job Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.