TweetFollow Us on Twitter

August 91 - Think Pascal 4

Think Pascal 4

Don Sawtelle

Having just expressed August's final proof back to Bill Anderson-lacking this page, of course-I have only to write this column, then it's on to October. Instead of writing an August issue overview, I'll describe a small useful workaround for failure handling with Think Pascal 4 (announced August 6th, and now shipping).

Just What you've been waiting for…

Think Pascal 4 runs under System 7 in both 24- and 32-bit modes, and works fine with virtual memory. It has all the headers required for writing System 7-savvy applications, and supports far code, making it possible to create applications that require up to 256k of jump table space. You can find out more about these and other new features by calling Symantec (617-275-4800)-or better yet, just order the upgrade. Oh, and project updates have been optimized; MacApp compiles noticeably faster.

…and Now 99% reliable

Think Pascal 4 is much more reliable when working with large MacApp applications than was Think Pascal 3. Think Pascal 3 had a serious flaw with respect to MacApp; if anything called Failure while running in the Think environment, and some of the routines on the stack at the time were compiled with the D option in the project window checked (so that you could source-debug them), Think Pascal was likely to crash. It would sometimes crash right away, and sometimes later, when you were no longer even thinking of your past failures. And projects could sometimes get corrupted, causing nasty problems that didn't go away until you removed the code from the project and rebuilt, or created a new project from scratch.

Because of all this, life was difficult when debugging anything with Think Pascal 3 that involved failure handling. The most useful technique for debugging failures-setting a stop sign at the beginning of the Failure procedure, so that you can see the context of the error before MacApp's failure handling cuts back the stack and displays the error dialog-caused Think Pascal 3 to crash when a failure occurred. I find it convenient to write code that uses failure handling even for recovery from soft (non-catastrophic) errors, so this was a real problem for me.

With the new release, Think Pascal 4 provides a couple of replacements for the MacApp failure library that you can use when debugging in the Think environment-one for use with the MacApp debugger, one for without. These libraries call a special trap that causes the Think Pascal debugging environment to do the cleanup it needs to for each routine that was on the stack at the time of a failure.

In my experience, with these special failure libraries, Think Pascal 4 is now almost 100% reliable. Most mysterious crashes of the Think environment eventually turn out to be my own runaway code trashing something that's none of its business. (Oh, for a protected memory space!) There are only two limitations: (1) you have to compile your entire application, including MacApp, with the Think debugging option on, because the special failure library isn't smart about not calling the Think cleanup code if a routine on the stack wasn't compiled with the Think debugging option; and (2) for some reason, which I hope Symantec technical support can eventually explain, a failure during application initialization(IMyApplication) still crashes Think Pascal, if you're using the special failure libraries.

The first limitation isn't serious unless your code runs too slowly when the entire application is compiled with Think debugging on. And it's safe to compile units that won't fail, and that don't call any routines which could fail, without Think debugging.

The second limitation seems to be the last remaining bit of Think Pascal's former unreliability that developers have lived with for so long. If your application does nothing complex during initialization, and your code doesn't have any bugs, you may not encounter the problem. I have an application that looks for devices during IMyApplication, and that uses failure handling as a way to gracefully handle their absence; if you do something like this, you'll be sure to repeatedly encounter the hard crash.

I've come up with a simple workaround. It's kind of odd, but it seems to circumvent the problem, and not cause any new ones, either.

How to keep the special failure library from crashing Think Pascal 4

First, make sure you have a correct TMyApplication.Initialize method that puts your application object in a state where it can be safely freed if something goes wrong. Actually, nothing will go wrong-famous last words-but just in case. Then, in your MMyApplication.p unit, call IApplication instead of IMyApplication. Also, change IMyApplication so that it doesn't call IApplication. Add a boolean to TMyApplication called fPostInitialize, set it to false in TMyApplication.Initialize, and override MacApp's PollEvent as shown in the PollEvent listing. With these changes, the significant initialization code for your application-the code that might fail-won't execute until MacApp's event handling loop runs for the first time. Thus you'll avoid the possibility of failure at a time when it could crash Think Pascal.

Do be sure to contain these changes within {$IFC} directives, so that it's easy to build your standalone application without them. This workaround is a hack that's just intended for using during debugging; you don't want it in your final code! n

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Lyn 1.8.5 - Lightweight image browser an...
Lyn is a fast, lightweight image browser and viewer designed for photographers, graphic artists, and Web designers. Featuring an extremely versatile and aesthetically pleasing interface, it delivers... Read more
Apple iOS 10.2.1 - The latest version of...
iOS 10 is the biggest release of iOS ever. A massive update to Messages brings the power of the App Store to your conversations and makes messaging more personal than ever. Find your route with... Read more
Apple Security Update 2016-003 Supplemen...
Apple Security Update is recommended for all users and improves the security of OS X. For detailed information about the security content of this update, please visit: http://support.apple.com/kb/... Read more
Apple macOS Sierra 10.12.3 - The latest...
With Apple macOS Sierra, Siri makes its debut on Mac, with new features designed just for the desktop. Your Mac works with iCloud and your Apple devices in smart new ways, and intelligent... Read more
BetterTouchTool 1.992 - Customize Multi-...
BetterTouchTool adds many new, fully customizable gestures to the Magic Mouse, Multi-Touch MacBook trackpad, and Magic Trackpad. These gestures are customizable: Magic Mouse: Pinch in / out (zoom... Read more
Viber 6.5.5 - Send messages and make cal...
Viber lets you send free messages and make free calls to other Viber users, on any device and network, in any country! Viber syncs your contacts, messages and call history with your mobile device, so... Read more
Opera 42.0.2393.137 - High-performance W...
Opera is a fast and secure browser trusted by millions of users. With the intuitive interface, Speed Dial and visual bookmarks for organizing favorite sites, news feature with fresh, relevant content... Read more
iClock Pro 3.4.7 - Customize your menuba...
iClock Pro is a menu bar replacement clock for Apple's default clock. iClock Pro is an update, total rewrite and improvement to the popular iClock. Have the day, date and time in different fonts and... Read more
PhotoDesk 4.1.5 - Instagram client for p...
PhotoDesk lets you view, like, comment, and download Instagram pictures/videos. (NO Uploads! / Image Posting! Instagram forbids that! AND you need an existing Instagram account). But you can do so... Read more
Capo 3.5.1 - Slow down and learn to play...
Capo lets you slow down your favorite songs so you can hear the notes and learn how they are played. With Capo, you can quickly tab out your songs atop a highly-detailed OpenCL-powered spectrogram... Read more

Clash Royale gets some serious balance u...
| Read more »
Ironhide Game Studio prepares for a busy...
Kingdom Rush breathed fresh life into the tired tower defense genre way back in 2012. The game was a robust challenge that somehow managed to lift you up, rather than leaving you feeling crushed and hopeless. The rich array of unit types and... | Read more »
Collect pets and sling arrows in Arcane...
Mobile gaming is a crowded market, but regular updates are a good way to keep us attention-short players keen. The brand new content in Arcane Online is a prime example. Published by Japanese developer Gala, Arcane Online is a fantasy MMO that... | Read more »
Super Mario Run dashes onto Android in M...
Super Mario Run was one of the biggest mobile launches in 2016 before it was met with a lukewarm response by many. While the game itself plays a treat, it's pretty hard to swallow the steep price for the full game. With that said, Android users... | Read more »
WarFriends Beginner's Guide: How to...
Chillingo's new game, WarFriends, is finally available world wide, and so far it's a refreshing change from common mobile game trends. The game's a mix of tower defense, third person shooter, and collectible card game. There's a lot to unpack here... | Read more »
Super Gridland (Entertainment)
Super Gridland 1.0 Device: iOS Universal Category: Entertainment Price: $1.99, Version: 1.0 (iTunes) Description: Match. Build. Survive. "exquisitely tuned" - Rock Paper Shotgun No in-app purches, and no ads! | Read more »
Red's Kingdom (Games)
Red's Kingdom 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: Mad King Mac has kidnapped your father and stolen your golden nut! Solve puzzles and battle goons as you explore and battle your... | Read more »
Turbo League Guide: How to tame the cont...
| Read more »
Fire Emblem: Heroes coming to Google Pla...
Nintendo gave us our first look at Fire Emblem: Heroes, the upcoming mobile Fire Emblem game the company hinted at last year. Revealed at the Fire Emblem Direct event held today, the game will condense the series' tactical RPG combat into bite-... | Read more »
ReSlice (Music)
ReSlice 1.0 Device: iOS Universal Category: Music Price: $9.99, Version: 1.0 (iTunes) Description: Audio Slice Machine Slice your audio samples with ReSlice and create flexible musical atoms which can be triggered by MIDI notes or... | Read more »

Price Scanner via MacPrices.net

Deal alert! 13-inch 2.0GHz MacBook Pros for $...
B&H Photo has the new 2016 13″ 2.0GHz non-Touch Bar MacBook Pros in stock today and on sale for $225 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 13″ 2.0GHz MacBook Pro... Read more
Free LibreOffice Portable 5.2.4 Complete Offi...
PortableApps.com and The Document Foundation have announce the release of LibreOffice Portable 5.2.4. LibreOffice Portable is an Open Source full-featured office suite — including a word processor,... Read more
Apple Planning Three New Tablets For 2017 – D...
Digitimes’ Rebecca Kuo and Joseph Tsai say that unnamed insider sources report Apple having three new tablets in the pipeline for 2017 release: a 9.7-inch model with a friendly price range, a new mid... Read more
Roundup of 15-inch Touch Bar MacBook Pro sale...
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 refurbished iPad Pros available for up...
Apple has Certified Refurbished 9″ and 12″ Apple iPad Pros available for up to $160 off the cost of new iPads. An Apple one-year warranty is included with each model, and shipping is free: - 32GB 9″... Read more
16GB iPad Air 2, Apple refurbished, available...
Apple has Certified Refurbished 16GB iPad Air 2s available for $319 including free shipping. A standard Apple one-year is included. Their price is $60 off original MSRP for this model. Read more
Apple iMacs on sale for up to $120 off MSRP
B&H Photo has 21″ and 27″ Apple iMacs on sale for up to $120 off MSRP, each including free shipping plus NY sales tax only: - 27″ 3.3GHz iMac 5K: $2199 $100 off MSRP - 27″ 3.2GHz/1TB Fusion iMac... Read more
Apple refurbished Apple TVs available for up...
Apple has Certified Refurbished 32GB and 64GB Apple TVs available for up to $30 off the cost of new models. Apple’s standard one-year warranty is included with each model, and shipping is free: -... Read more
Save up to $350 with Apple Certified Refurbis...
Apple has Certified Refurbished 2015 21″ & 27″ iMacs available for up to $350 off MSRP. Apple’s one-year warranty is standard, and shipping is free. The following models are available: - 21″ 3.... Read more
2015 12-inch Retina MacBooks, Apple refurbish...
Apple has Certified Refurbished 2015 12″ Retina MacBooks available for up to $410 off original MSRP. Apple will include a standard one-year warranty with each MacBook, and shipping is free. The... Read more

Jobs Board

*Apple* & PC Desktop Support Technician...
Apple & PC Desktop Support Technician job in Manhattan, NY Introduction: We have immediate job openings for several Desktop Support Technicians with one of our most Read more
*Apple* & PC Desktop Support Technician...
Apple & PC Desktop Support Technician job in Stamford, CT We have immediate job openings for several Desktop Support Technicians with one of our most well-known 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
*Apple* Site Security Manager - Apple (Unite...
# Apple Site Security Manager Job Number: 54692472 Culver City, California, United States Posted: Jan. 19, 2017 Weekly Hours: 40.00 **Job Summary** The Apple Read more
*Apple* macOS Systems Integration Administra...
…most exceptional support available in the industry. SCI is seeking an Junior Apple macOS systems integration administrator that will be responsible for providing Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.