TweetFollow Us on Twitter

Nov 95 Tips
Volume Number:11
Issue Number:11
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

Two Screen MacsBug

One feature of MacsBug that I like is the "swap" command, which lets you leave a second monitor display the debugger (and punches it out of the desktop).

Then, if each DebugStr() ends in ";g" you will get an onscreen log of the last 10 or 15 breaks. I used this to track an elusive bug that would freeze my Mac and trash Macsbug memory... I could see which breakpoint went last.

Matt Slot

Informant in the Menu Bar

I do drivers, and you just plain can’t set a breakpoint in ADB completion routines (freezes the keyboard so MacsBug is worthless!).

So I throw one of the routines below into the routine to see when a piece of code gets executed.

What does it do? It "lights up" a bar (length dependant on screen resolution) in the menu bar. So if you DotToggle(300); you get a flashing short line in the menu bar.

[Leave this out of production code! Beware of using this on 24 bit color screens. Make sure that the value of where will not cause anything to be written into the alpha channel. Your best bet is to test with the screen that’s only 8 bits deep. -sgs]

void DotOn(long where) {
   long  *dot;
   dot = (long *)(LMGetScrnBase() + where);
   *dot |= -1;
}
void DotOff(long where) {
   long  *dot;
   dot = (long *)(LMGetScrnBase() + where);
   *dot &= 0;
}
void DotToggle(long where) {
   long  *dot;
   dot = (long *)(LMGetScrnBase() + where);
   *dot ^= -1;
}

Dave Fleck

Informative Cursors

One technique that I have used in the past where dropping into the debugger wasn't an option, and logging wasn't getting flushed in time/took too long, was to create a bunch of cursors numbering 00 - 99, and made a call to set the cursor and return the number of the previous cursor:

routine1()
{
short oldCursor = setDebugCursor(15);
    ...
    (void) setDebugCursor(oldCursor);
}

This way when the machine froze, the cursor would tell me what routine it had frozen in.

Tom Kimpton

MPW Editor Primitives

The MPW Command Reference describes 32 editor primitives which may be attached to any key sequence using the SetKey command. While the SetKey command itself is useful, the list of editor primitives alone is useful to MPW script writers.

Though only documented for use with SetKey, editor primitives may be used like any other MPW command: in scripts, command aliases, or AddMenu items. There are a couple of advantages:

1) They only work on the active window and have sharply defined functions, you don’t have to remember any selection expressions or argument lists. Compare:

 MoveStartOfFile

with

       Find • "{Active}"

2) They’re fast. I haven’t put a stopwatch to it, but you can see the difference immediately in running a script that uses the primitives and one that doesn’t.

The MPW Command reference lists these 32 primitives, the names of which should be self-explanatory:

DeleteCharLeft

DeleteCharRight

DeleteEndOfFile

DeleteEndOfLine

DeleteStartOfFile

DeleteStartOfLine

DeleteWordLeft

DeleteWordRight

MoveCharLeft

MoveCharRight

MoveEndOfLine

MoveLineDown

MoveLineUp

MovePageDown

MovePageUp

MoveStartOfFile

MoveStartOfLine

MoveWordLeft

MoveWordRight

SelectCharLeft

SelectCharRight

SelectEndOfFile

SelectEndOfLine

SelectLineDown

SelectLineUP

SelectPageDown

SelectPageUp

SelectStartOfFile

SelectStartOfLine

SelectWordLeft

SelectWordRight

There are also at least five primitives that aren’t in the command reference:

ScrollEnd

ScrollHome

ScrollPageDn

ScrollPageUp

DebuggerCommand

I can understand why Apple might not want users to casually drop into MacsBug from an MPW script, but I wonder why they chose not to document the scrolling commands? Whatever the reason, you should obviously use caution when playing with undocumented features.

Lee David Rimar
Absoft Corporation

Once Bitten Twice Shy

HGetState does not return a valid handle state when you pass it an empty handle (one whose master pointer is NULL). Instead, it returns an error code, so before you call HGetState, be sure to check that the handle isn’t empty and execute an alternate code path if it is.

I was bitten by this because I was using HGetState to determine if a handle was to a resource, and the resourced had been purged, so HGetStaate returned an error code instead of the handle flags and I incorrectly thought the handle wasn’t to a resource.

This is documented in Inside Macintosh, Memory, p. 1-61, but it bears some repeating. Remember to check the error values returned by the toolbox calls.

Eric Schlegel

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

5 slither.io mash-ups we'd love to...
If there's one thing that slither.io has proved, it's that the addictive gameplay of Agar.io can be transplanted onto basically anything and it will still be good fun. It wouldn't be surprising if we saw other developers jumping on the bandwagon,... | Read more »
How to navigate the terrain in Sky Charm...
Sky Charms is a whimsical match-'em up adventure that uses creative level design to really ramp up the difficulty. [Read more] | Read more »
Victorious Knight (Games)
Victorious Knight 1.3 Device: iOS Universal Category: Games Price: $1.99, Version: 1.3 (iTunes) Description: New challenges awaits you! Experience fresh RPG experience with a unique combat mechanic, packed with high quality 3D... | Read more »
Agent Gumball - Roguelike Spy Game (Gam...
Agent Gumball - Roguelike Spy Game 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: Someone’s been spying on Gumball. What the what?! Two can play at that game! GO UNDERCOVERSneak past enemy... | Read more »
Runaway Toad (Games)
Runaway Toad 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: It ain’t easy bein’ green! Tap, hold, and swipe to help Toad hop to safety in this gorgeous new action game from the creators of... | Read more »
PsyCard (Games)
PsyCard 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: From the makers och Card City Nights, Progress To 100 and Ittle Dew PSYCARD is a minesweeper-like game set in a cozy cyberpunk... | Read more »
Sago Mini Robot Party (Education)
Sago Mini Robot Party 1.0 Device: iOS Universal Category: Education Price: $2.99, Version: 1.0 (iTunes) Description: -- Children's Technology Review Editor's Choice -- | Read more »
How to get a high score in every level o...
Sky Charms is an adorable match three puzzler that provides a decent challenge thanks to its creative level design. It regularly presents something new, forcing you to think on your feet. [Read more] | Read more »
Apestorm: Full Bananas (Games)
Apestorm: Full Bananas 1.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0 (iTunes) Description: ***Launch sale – limited time only!*** Fugitive Apes have taken to the skies in search of revenge after humans have... | Read more »
How to create bigger words in Spellspire
Words have power. At least they do in Spellspire,a game about blasting out magical attacks by making words out of a jumble of letters. And it's a lot of fun. But if you want to be the best, you're going to have to think tactically when you start... | Read more »

Price Scanner via MacPrices.net

15-inch 2.2GHz Retina MacBook Pro on sale for...
Amazon.com has the 15″ 2.2GHz Retina MacBook Pro on sale for $1699.99 including free shipping. Their price is $300 off MSRP, and it’s the lowest price available for this model from any reseller (and... Read more
Apple Beats Microsoft at Own Game; Amazon Pri...
First quarter seasonality combined with an overall disinterested customer base led to an annual decline of 14.7% in worldwide tablet shipments during the first quarter of 2016 (1Q16). Worldwide... Read more
Aleratec Releases Mac Software Upgrade for 1...
California based Aleratec Inc., designer, developer and manufacturer of Portable Device Management (PDM) charge/sync products for mobile devices and professional-grade duplicators for hard disk... Read more
Sale! Amazon offers 27-inch iMac, 13-inch 2.9...
Amazon has the 27″ 3.2GHz 5K iMac and the 13″ 3.9GHz Retina MacBook Pro on sale for $300 off MSRP, each including free shipping, for a limited time: - 27″ 3.2GHz/1TB HD 5K iMac (model MK462LL/A): $... Read more
Apple refurbished 13-inch Retina MacBook Pros...
Apple has Certified Refurbished 13″ Retina MacBook Pros available for up to $270 off the cost of new models. An Apple one-year warranty is included with each model, and shipping is free: - 13″ 2.7GHz... Read more
13-inch 2.7GHz/128GB Retina MacBook Pro on sa...
Take $200 off MSRP on the price of a new 13″ 2.7GHz/128GB Retina MacBook Pro (model MF839LL/A) at Amazon. Shipping is free: - 13″ 2.7GHz/128GB Retina MacBook Pro: $1099.99 $200 off MSRP Act now if... Read more
Apple refurbished clearance 15-inch Retina Ma...
Apple has Certified Refurbished 2014 15″ 2.2GHz Retina MacBook Pros available for $1609, $390 off original MSRP. Apple’s one-year warranty is included, and shipping is free. They have refurbished 15... Read more
27-inch 5K iMacs on sale for up to $150 off M...
B&H Photo has 27″ 5K iMacs on sale for up to $150 off MSRP including free shipping plus NY sales tax only: - 27″ 3.3GHz iMac 5K: $2199 $100 off MSRP - 27″ 3.2GHz/1TB Fusion iMac 5K: $1849.99 $150... Read more
What Does The Refreshed 12-Inch MacBook Tell...
A lot of commentators are complaining that Apple’s update of the 12-Inch MacBook last week is a bit of a damp squib. I don’t know what they were expecting, since it would be very unlike Apple to do a... Read more
Free Wittify Keyboard Now Available On The Ap...
A team of Harvard Business School students have announced that the Wittify Keyboard, a new app utility for iOS devices, is now available on the Apple App Store. The Wittify keyboard and application... Read more

Jobs Board

*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
*Apple* Solutions Consultant - Apple (United...
# Apple Solutions Consultant Job Number: 48260200 Phoenix, Arizona, United States Posted: Apr. 22, 2016 Weekly Hours: 40.00 **Job Summary** As an Apple Solutions Read more
Restaurant Manager (Neighborhood Captain) - A...
…in every aspect of daily operation. WHY YOU'LL LIKE IT: You'll be the Big Apple . You'll solve problems. You'll get to show your ability to handle the stress and Read more
Simply Mac *Apple* Specialist- Service Repa...
Simply Mac is the largest premier retailer of Apple products in the nation. In order to support our growing customer base, we are currently looking for a driven 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
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.