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

Google Drive 1.20 - File backup and shar...
Google Drive is a place where you can create, share, collaborate, and keep all of your stuff. Whether you're working with a friend on a joint research project, planning a wedding with your fiancé, or... Read more
Simon 4.0.3 - Monitor changes and crashe...
Simon monitors websites and alerts you of crashes and changes. Select pages to monitor, choose your alert options, and customize your settings. Simon does the rest. Keep a watchful eye on your... Read more
Vitamin-R 2.23 - Personal productivity t...
Vitamin-R creates the optimal conditions for your brain to work at its best by structuring your work into short bursts of distraction-free, highly focused activity alternating with opportunities for... Read more
iDefrag 5.0.0 - Disk defragmentation and...
iDefrag helps defragment and optimize your disk for improved performance. Features include: Supports HFS and HFS+ (Mac OS Extended). Supports case sensitive and journaled filesystems. Supports... Read more
PCalc 4.2 - Full-featured scientific cal...
PCalc is a full-featured, scriptable scientific calculator with support for hexadecimal, octal, and binary calculations, as well as an RPN mode, programmable functions, and an extensive set of unit... Read more
FileZilla 3.10.2 - Fast and reliable FTP...
FileZilla (ported from Windows) is a fast and reliable FTP client and server with lots of useful features and an intuitive interface. Version 3.10.2: Note: Now requires a 64-bit Intel processor.... Read more
The Hit List 1.1.11 - Advanced reminder...
The Hit List manages the daily chaos of your modern life. It's easy to learn - it's as easy as making lists. And it's powerful enough to let you plan, then forget, then act when the time is right.... Read more
Bartender 1.2.32 - Organize your menu ba...
Bartender lets you organize your menu bar apps. Features: Lets you tidy your menu bar apps how you want. See your menu bar apps when you want. Hide the apps you need to run, but do not need to... Read more
ClamXav 2.7.5 - Free virus checker, base...
ClamXav is a free virus checker for OS X. It uses the tried, tested, and very popular ClamAV open source antivirus engine as a back end. I hope you like and use ClamXav a lot and that it helps keep... Read more
xScope 4.1.2 - Onscreen graphic measurem...
xScope is powerful set of tools that are ideal for measuring, inspecting, and testing on-screen graphics and layouts. Its tools float above your desktop windows and can be accessed via a toolbar,... Read more

Dungeon Hunter 5 Coming on March 12
Gameloft has excitedly announced that Dungeon Hunter 5 is on its way! Once again, you will adventure across the land of Valenthia exploring dungeons and fighting monsters. The game will have a new asynchronous multiplayer mode called Strongholds... | Read more »
It Came From Canada: Jurojin: Immortal N...
At this point it’s pretty safe to say that no MOBA is going to dethrone Dota 2 and League of Legends anytime soon. After all, if Batman can’t do it, nobody can. However, with a genre as popular and profitable as this one, there’s still room for... | Read more »
Tiny Farm – Animals, Tractors and Advent...
Tiny Farm – Animals, Tractors and Adventures! Review By Amy Solomon on March 3rd, 2015 Our Rating: :: LIVELY LANDSCAPESUniversal App - Designed for iPhone and iPad Tiny Farm – Animals, Tractors and Adventures! includes farm-related... | Read more »
This Week at 148Apps: February 23-27, 20...
Final February Fun at 148Apps   How do you know what apps are worth your time and money? Just look to the review team at 148Apps. We sort through the chaos and find the apps you’re looking for. The ones we love become Editor’s Choice, standing out... | Read more »
GDC 2015 – Does Not Commute is Definitel...
GDC 2015 – Does Not Commute is Definitely a Game You Should Keep an Eye on Posted by Rob Rich on March 2nd, 2015 [ permalink ] We were teased about Mediocre Games’ (Smash Hit, | Read more »
F84 Games & POW! Announce Stan Lee V...
F84 Games has announced that it is working with legendary comic creator Stan Lee and POW! Entertainment to produce Stan Lee’s Hero Command. The game will be a action adventure of heroic proportions. | Read more »
Setlyst Keeps Your Set Straight So You C...
Setlyst Keeps Your Set Straight So You Can Focus On Rocking Out. Posted by Jessica Fisher on March 2nd, 2015 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Space is Vast, So Space Agency Has a Vas...
Space is Vast, So Space Agency Has a Vast New Update! Posted by Jessica Fisher on March 2nd, 2015 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Size DOES Matter Review
Size DOES Matter Review By Campbell Bird on March 2nd, 2015 Our Rating: :: HARD TO BEATUniversal App - Designed for iPhone and iPad This rhythm game has a unique control scheme and performance system that make it feel like a true... | Read more »
The first ever action 3D card battler Al...
On the other hand, you probably haven’t played an action 3D card battler – until now. Step forward, All Star Legion. All Star Legion is a 3D QTE-based action RPG card battler, but fear not – the game itself isn’t as convoluted as its description.... | Read more »

Price Scanner via MacPrices.net

Another Tranche Of IBM MobileFirst For iOS Ap...
IBM has announced the next expansion phase for  its IBM MobileFirst for iOS portfolio, with a troika of new apps to address key priorities for the Banking and Financial Services, Airline and Retail... Read more
Sale! 15-inch Retina MacBook Pros for up to $...
B&H Photo has the new 2014 15″ Retina MacBook Pros on sale for up to $250 off MSRP for a limited time. Shipping is free, and B&H charges NY sales tax only: - 15″ 2.2GHz Retina MacBook Pro: $... Read more
WaterField Designs Introduces the Minimalist...
With Apple Pay gaining popularity, Android Pay coming in May 2015, and loyalty cards and receipts that can be accessed from smartphones, San Francisco’s WaterField Designs observes that it may be... Read more
Sale! 15-inch 2.2GHz Retina MacBook Pro for $...
 Best Buy has the 15″ 2.2GHz Retina MacBook Pro on sale for $1774.99 $1799.99, or $225 off MSRP. Choose free home shipping or free local store pickup (if available). Price valid for online orders... Read more
13-inch 2.5GHz MacBook Pro (refurbished) avai...
The Apple Store has Apple Certified Refurbished 13″ 2.5GHz MacBook Pros available for $170 off the cost of new models. Apple’s one-year warranty is standard, and shipping is free: - 13″ 2.5GHz... Read more
13-inch 2.5GHz MacBook Pro on sale for $100 o...
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
27-inch 3.5GHz 5K iMac in stock today and on...
 B&H Photo has the 27″ 3.5GHz 5K iMac in stock today and on sale for $2299 including free shipping plus NY sales tax only. Their price is $200 off MSRP, and it’s the lowest price available for... Read more
Apple Launches Free Web-Based Pages and Other...
Apple’s new Web-only access to iWork productivity apps is a free level of iCloud service available to anyone, including people who don’t own or use Apple devices. The service includes access to Apple... Read more
Survey Reveals Solid State Disk (SSD) Technol...
In a recent SSD technology use survey, Kroll Ontrack, a firm specializing in data recovery, found that while nearly 90 percent of respondents leverage the performance and reliability benefits of SSD... Read more
Save up to $600 with Apple refurbished Mac Pr...
The Apple Store is offering Apple Certified Refurbished Mac Pros for up to $600 off the cost of new models. An Apple one-year warranty is included with each Mac Pro, and shipping is free. The... Read more

Jobs Board

*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
*Apple* Pay Automation Engineer - iOS System...
**Job Summary** At Apple , great ideas have a way of becoming great products, services, and customer experiences very quickly. Bring passion and dedication to your job Read more
Sr. Technical Services Consultant, *Apple*...
**Job Summary** Apple Professional Services (APS) has an opening for a senior technical position that contributes to Apple 's efforts for strategic and transactional Read more
Event Director, *Apple* Retail Marketing -...
…This senior level position is responsible for leading and imagining the Apple Retail Team's global engagement strategy and team. Delivering an overarching brand Read more
*Apple* Pay - Site Reliability Engineer - Ap...
**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
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.