TweetFollow Us on Twitter

Dec 95 Tips
Volume Number:11
Issue Number:12
Column Tag:Tips & Tidbits

Tips & Tidbits

By Steve Sisak, Contributing Editor

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

TIP OF THE MONTH

Arguments To “s” In MacsBug

In MacsBug, the s [step] command will take an argument which is either a count or a condition on which to stop. This can be very useful for unwinding a twisty bit of code. For example, if you keep crashing in a particular spot, but you can’t tell how you got there or what happened just before, you can break before everything goes wrong and type


  s (pc == <badspot>)

Where badspot is where you know things are wrong. Macsbug will step through all of the instructions in between here and there. You can then examine the path taken in the scrollback or, if you turn on the log first, look at it all offline with an editor. With the newest versions of MacsBug, you can even step over mixed mode. Note that it’s possible for find weirder problems, too:


 s (a0 == 0)

will step until a0 equals 0.

 

 s (<addr>^ != <current value>)

will step until the long at <addr> changes.

You can use this trick to find a really wide variety of problems. Should you use this tip, donate my fee to the American Red Cross.

- Tim Dierks

They Said I Couldn’t
Return Errors From Constructors

I have read several times that “you can’t return an error from a constructor”. This is not entirely true. See the following code example:

class exampleClass : parentClass
{
  exampleClass( int arg1, OSErr& errOut );
    // initialization constructor
...etc....
};

exampleClass::exampleClass( int arg1, OSErr& errOut )
 : parentClass()  // parent class constructor explicitly called
 , memberData() // instance variable's explict constructor
{
//  errOut = noErr;  see note #4 below
  errOut = someSystemCall( arg1 );
}

void main ( void )
{
   OSErr  err;
   exampleClass  aVar( 12, err );
   if ( err != noErr ) 
   {....etc....
}

This example “obviously” returns error information.

However, errOut will NOT have a known value if the following occurs:

1. parentClass’s explicit constructor throws an exception.

2. memberData’s explicit constructor throws an exception.

3. someSystemCall throws an exception. This example used explicit contructor calls, but the same is true for implicit constructor calls to parent classes and member data varables.

4. if the errOut = noErr line is uncommented, then at least errOut can have a known value in the absence of other exceptions.

Of course, since main isn’t doing try/catch, then the test of err != noErr is not going to happen when an exception occurs, either.

- C. Keith Ray

Is Your App Windowshade Savvy?

Many apps change the cursor within certain areas of their windows. This may be to provide the crosshairs in a drawing window, or a hand cursor if something can be dragged in an area of your window. Unfortunately, many applications forget to check whether their window is windowshaded or not. If their window is windowshaded but still the front window, they go ahead and change the cursor anyway, leading to the effect of the cursor changing over “empty space.” Looks ugly. Here’s the fix:

if (EmptyRgn( ((WindowPeek)TheWindow)->contRgn )) 
//window shade has been used

Don’t change the cursor;

else

Go ahead and change the cursor;

In the above example, TheWindow is the windowptr to the window who’s areas we are changing the cursor for.

- Richard Unger and Eric Bourque

Shortcut to Open Header Files In CodeWarrior

Here is a feature that I’d long hoped for, and recently, by accident, found.

In Metrowerk’s IDE, typing ‘command tab’ will open the corresponding .h or .cp file. For example, if you’re working in a source file named “FileName.cp” typing ‘command tab’ will open “FileName.h”. This is an extremely useful feature that I hope Symantec will adopt.

- Norman Basha

Drop Into MacsBug at a Predictable Address

When dropping into MacsBug, I often find myself in the wrong application’s code. For example, lets say I want to force-quit the finder using “es” from MacsBug. (command-option-escape will quit and then restart the Finder). To make sure the Finder is the frontmost app, I hold the mouse down in one of the Finder’s menus and press the interrupt key, and I’m dropped in at a known location (a small loop within the menu manager). Not only that, but the current menu manager is emulated on PowerMacs, further ensuring my safety. Then a simple “es” quits the Finder.

- Damon Cokenias

Lock Your Libraries, Prevent Changes

Here’s a tip that may be obvious, but it’s useful, if somewhat simple.

If you don’t want to modify the standard libraries included in a development environment (the source to PowerPlant or TCL for example) you can use the following script to lock all the files. I use this script in MPW, but should work with ToolServer as well:

### First set the current directory to the folder containing the sources 
to lock
### note that this script does sub-folders also.
### replace "xxx" with your path, e.g., "HD:MPW:Interfaces:"
directory "Full path to the folder in which the files are:"

### Then set the lock bit to ON for all files which are of
### type 'TEXT' in the current directory and all sub-directories
### Notes:
###   remove "-r" to skip sub-directories
###   make the "L" lowercase ("l") to un-lock files
###   the -f is for full paths, -s to supress directory listings
SetFile -a L `files -r -f -s -t 'TEXT'`

Anyway, just thought I’d pass it on. It’s particularly useful while using a class browser like Object Master, where you can browse all classes and it’s easy to end up editing one of the supplied classes in PowerPlant/Think Class Library/MacApp.

- Tyler Morrison

[AppleScript also supports locking and unlocking of files. Simply modify the “locked” property of x, where x is a file alias or file name with: set the locked of file x to true

EdAsst - jtk]

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

NetShade 6.3.1 - Browse privately using...
NetShade is an anonymous proxy and VPN app+service for Mac. Unblock your Internet through NetShade's high-speed proxy and VPN servers spanning seven countries. NetShade masks your IP address as you... Read more
Dragon Dictate 4.0.7 - Premium voice-rec...
With Dragon Dictate speech recognition software, you can use your voice to create and edit text or interact with your favorite Mac applications. Far more than just speech-to-text, Dragon Dictate lets... Read more
Persecond 1.0.2 - Timelapse video made e...
Persecond is the easy, fun way to create a beautiful timelapse video. Import an image sequence from any camera, trim the length of your video, adjust the speed and playback direction, and you’re done... Read more
GIMP 2.8.14p2 - Powerful, free image edi...
GIMP is a multi-platform photo manipulation tool. GIMP is an acronym for GNU Image Manipulation Program. The GIMP is suitable for a variety of image manipulation tasks, including photo retouching,... Read more
Sandvox 2.10.2 - Easily build eye-catchi...
Sandvox is for Mac users who want to create a professional looking website quickly and easily. With Sandvox, you don't need to be a Web genius to build a stylish, feature-rich, standards-compliant... Read more
LibreOffice 5.0.1.2 - Free, open-source...
LibreOffice is an office suite (word processor, spreadsheet, presentations, drawing tool) compatible with other major office suites. The Document Foundation is coordinating development and... Read more
f.lux 36.1 - Adjusts the color of your d...
f.lux makes the color of your computer's display adapt to the time of day, warm at night and like sunlight during the day. Ever notice how people texting at night have that eerie blue glow? Or wake... Read more
VirtualBox 5.0.2 - x86 virtualization so...
VirtualBox is a family of powerful x86 virtualization products for enterprise as well as home use. Not only is VirtualBox an extremely feature rich, high performance product for enterprise customers... Read more
File Juicer 4.43 - Extract images, video...
File Juicer is a drag-and-drop can opener and data archaeologist. Its specialty is to find and extract images, video, audio, or text from files which are hard to open in other ways. In computer... Read more
Apple MainStage 3.2 - Live performance t...
MainStage 3 makes it easy to bring to the stage all the same instruments and effects that you love in your recording. Everything from the Sound Library and Smart Controls you're familiar with from... Read more

ReBoard: Revolutionary Keyboard (Utilit...
ReBoard: Revolutionary Keyboard 1.0 Device: iOS Universal Category: Utilities Price: $1.99, Version: 1.0 (iTunes) Description: Do everything within the keyboard without switching apps! If you are in WhatsApp, how do you schedule a... | Read more »
Tiny Empire (Games)
Tiny Empire 1.1.3 Device: iOS Universal Category: Games Price: $2.99, Version: 1.1.3 (iTunes) Description: Launch cannonballs and blow tiny orcs into thousands of pieces in this intuitive fantasy-themed puzzle shooter! Embark on an... | Read more »
Astropad Mini (Productivity)
Astropad Mini 1.0 Device: iOS iPhone Category: Productivity Price: $4.99, Version: 1.0 (iTunes) Description: *** 50% off introductory price! ​*** Get the high-end experience of a Wacom tablet at a fraction of the price with Astropad... | Read more »
Emo Chorus (Music)
Emo Chorus 1.0.0 Device: iOS Universal Category: Music Price: $1.99, Version: 1.0.0 (iTunes) Description: Realistic Choir simulator ranging from simple Chorus emulation to full ensemble Choir with 128 members. ### introductory offer... | Read more »
Forest Spirit (Games)
Forest Spirit 1.0.5 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0.5 (iTunes) Description: | Read more »
Ski Safari 2 (Games)
Ski Safari 2 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: The world's most fantastical, fun, family-friendly skiing game is back and better than ever! Play as Sven's sister Evana, share... | Read more »
Lara Croft GO (Games)
Lara Croft GO 1.0.47768 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.47768 (iTunes) Description: Lara Croft GO is a turn based puzzle-adventure set in a long-forgotten world. Explore the ruins of an ancient... | Read more »
Whispering Willows (Games)
Whispering Willows 1.23 Device: iOS Universal Category: Games Price: $4.99, Version: 1.23 (iTunes) Description: **LAUNCH SALE 50% OFF** - Whispering Willows is on sale for 50% off ($4.99) until September 9th. | Read more »
Calvino Noir (Games)
Calvino Noir 1.1 Device: iOS iPhone Category: Games Price: $3.99, Version: 1.1 (iTunes) Description: The film noir stealth game. Calvino Noir is the exploratory, sneaking adventure through the 1930s European criminal underworld.... | Read more »
Angel Sword (Games)
Angel Sword 1.0 Device: iOS Universal Category: Games Price: $6.99, Version: 1.0 (iTunes) Description: Prepare to adventure in the most epic full scale multiplayer 3D RPG for mobile! Experience amazing detailed graphics in full HD.... | Read more »

Price Scanner via MacPrices.net

Tablet Screen Sizes Expanding as iPad Pro App...
Larger screen sizes are gaining favor as the tablet transforms into a productivity device, with shipments growing 185 percent year-over-year in 2015. According to a new Strategy Analytics’ Tablet... Read more
Today Only: Save US$50 on Adobe Elements 13;...
Keep the memories. lose the distractions. Summer’s winding down and it’s time to turn almost perfect shots into picture perfect memories with Elements 13. And get the power to edit both photos and... Read more
1.4GHz Mac mini on sale for $449, save $50
Best Buy has the 1.4GHz Mac mini on sale for $50 off MSRP on their online store. Choose free shipping or free local store pickup (if available). Price for online orders only, in-store price may vary... Read more
12-inch 1.1GHz Gold MacBook on sale for $1149...
B&H Photo has the 12″ 1.1GHz Gold Retina MacBook on sale for $1149.99 including free shipping plus NY sales tax only. Their price is $150 off MSRP, and it’s the lowest price available for this... Read more
27-inch 3.3GHz 5K iMac on sale for $1849, sav...
Best Buy has the 27″ 3.3GHz 5K iMac on sale for $1849.99. Their price is $150 off MSRP, and it’s the lowest price available for this model. Choose free shipping or free local store pickup (if... Read more
Worldwide Tablet Shipments Expected to Declin...
Does Apple badly need a touchscreen convertible/hybrid laptop MacBook? Yes, judging from a new market forecast from the International Data Corporation (IDC) Worldwide Quarterly Tablet Tracker, which... Read more
Continued PC Shipment Shrinkage Expected Thro...
Worldwide PC shipments are expected to fall by -8.7 percent in 2015 and not stabilize until 2017, according to the latest International Data Corporation (IDC) Worldwide Quarterly PC Tracker data. The... Read more
Imminent iPhone 6s Announcement Leads To 103%...
NextWorth Solutions, with its online and in-store electronics trade-in programs including http://NextWorth.com, reports that it has experienced a 103 percent surge in quoted trade-in values over the... Read more
Weekend Deal: 13-inch Retina MacBook Pros for...
Save up to $100 on the purchase of a new 2015 13″ Retina MacBook Pro at the following resellers this weekend. Shipping is free with each model: 2.7GHz/128GB MSRP $1299 2.7GHz/... Read more
13-inch 2.5GHz MacBook Pro on sale for $999,...
B&H Photo has the 13″ 2.5GHz MacBook Pro on sale for $999.99 including free shipping plus NY sales tax only. Their price is $100 off MSRP. Read more

Jobs Board

Senior Payments Security Manager - *Apple*...
**Job Summary** Apple , Inc. is looking for a highly motivated, innovative and hands-on senior payments security manager to join the Apple Pay security team. You will Read more
Software QA Engineer, *Apple* Pay Security...
**Job Summary** Imagine what you could do here. At Apple , great ideas have a way of becoming great products, services, and customer experiences very quickly. Bring Read more
Business Process Engineer ( *Apple* Online S...
**Job Summary** The Apple Online Support Planning team is looking for an experienced Business Process engineer to lead key business process improvement initiatives Read more
*Apple* Solutions Consultant - Retail Sales...
**Job Summary** As an Apple Solutions Consultant (ASC) you are the link between our customers and our products. Your role is to drive the Apple business in a retail Read more
Product Design Engineer - *Apple* Watch - A...
**Job Summary** Product Design Engineer Job Description As a member of Apple 's Watch product design team, you will help to create the next generation of the world's Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.