TweetFollow Us on Twitter

Aug 98 Tips

Volume Number: 14 (1998)
Issue Number: 8
Column Tag: Tips & Tidbits

August 1998 Tips

by Steve Sisak, tips@mactech.com

Gotcha - Calling GetResource()

If you call Get1Resource(), expecting to get a resource from the topmost resource file, you can be unpleasantly surprised. With the introduction of the "Fonts" folder in System 7.1, a patch was made to the resource manager so that all the files in the fonts folder will appear to be part of the System file, even though they are not.

Most of the time this is not a problem, since most people don't care if a resource is in the System file or in a file in the fonts folder (or in the enabler, or in ROM).

However, if you absolutely need to know the file where a resource is loading from, you can use HomeResFile(). It will return the refNum of the resource file the resource came from.

Marshall Clow, Adobe Systems


Determining if a Resource File was Actually Opened

When you use any of the Resource Manager calls for opening a resource file, and the resource file is already open by the Resource Manager with that access, it will not open the file again. Instead, it returns the refNum of the already-open reference, and also does the equivalent of a UseResFile() on that refNum.

This means you have to be careful if your code is capable of opening and closing arbitrary resource files - if the Resource Manager didn't actually open the file for you (for example if you were to open your own application, or the System file, or a suitcase in the Fonts folder), then you must not close it with CloseResFile().

So how do you tell if the resource file was actually opened for you or not?

It's easy: if the resource file was opened, then its resource map will be added to the top of the in-memory chain of resource maps (pointed to by the "TopMapHndl" low-memory global). If not, then the chain remains unchanged.

The following sequence illustrates the idea:

  SInt16    TheResFile, PreviousResFile;
  Boolean   ReallyOpened;
  Handle    PreviousTop;

  PreviousResFile = CurResFile();
  PreviousTop = LMGetTopMapHndl();
  TheResFile = FSpOpenResFile(ResFileSpec, Permissions);

/* checking for errors omitted */

  ReallyOpened = LMGetTopMapHndl() != PreviousTop;

/* do your processing on the resources, then when finished, restore things as they were: */

  if (ReallyOpened)
    CloseResFile(TheResFile);
  UseResFile(PreviousResFile);

Lawrence D'Oliveiro, Hamilton, New Zealand


Serial Port Tidbits Comments

Thanks for the informative article bringing together a lot of previously hard to find information. I spent many hours digging around (and cursing!) trying to find that same info.

I had written a similar routine to your FindPortInfo() routine, and after checking mine, I initially thought there might be a bug in yours. I finally realized that your code was in fact right, but there is a subtlety which might not be apparent to readers.

In the line:

while ((crm = CRMSearch(crm)) != nil)

a key point is that you are reassigning to crm the result of the search. In my code I was using a temporary variable to pass to CRMSearch(), as in

while ((foundCRM = CRMSearch(tempCRM)) != nil)

This means that in my code, after the EqualString() check, I need to insert:

tempCRM->crmDeviceID = foundCRM->crmDeviceID;

to avoid a potential infinite loop.

Your code (and the code in the CTB book) avoids this by using the same variable in the assignment, but that also hides this subtle point CRMSearch() starts looking from the device ID passed to it in the crmDeviceID field of the CRMRecPtr passed to it.

One other thing I'd like to mention is that instead of your IsDriverOpen() routine, you could call the Connection Resource Manager routine CRMIsDriverOpen(), described in the Communications Toolbox 1.1 Engineering Notes (not in the original CTB book - the 1.1 notes are another hard-to-find source...)

Jim Wintermyre, E-mu Systems, Inc.

Ed Note: The fact that CRMSearch() looks at the deviceID and deviceType passed in and returns the device of the same type with the next higher ID. This is a subtlety worth noting. Also, the CTB 1.1 Engineering Notes are an important resource I forgot to mention in the original article.
-sgs

 
AAPL
$102.47
Apple Inc.
+2.71
MSFT
$44.88
Microsoft Corpora
+0.80
GOOG
$526.54
Google Inc.
+5.70

MacTech Search:
Community Search:

Software Updates via MacUpdate

RapidWeaver 6.0 - Create template-based...
RapidWeaver is a next-generation Web design application to help you easily create professional-looking Web sites in minutes. No knowledge of complex code is required, RapidWeaver will take care of... Read more
NTFS 12.0.39 - Provides full read and wr...
Paragon NTFS breaks down the barriers between Windows and OS X. Paragon NTFS effectively solves the communication problems between the Mac system and NTFS, providing full read and write access to... Read more
RestoreMeNot 2.0.3 - Disable window rest...
RestoreMeNot provides a simple way to disable the window restoration for individual applications so that you can fine-tune this behavior to suit your needs. Please note that RestoreMeNot is designed... Read more
Macgo Blu-ray Player 2.10.9.1750 - Blu-r...
Macgo Mac Blu-ray Player can bring you the most unforgettable Blu-ray experience on your Mac. Overview Macgo Mac Blu-ray Player can satisfy just about every need you could possibly have in a Blu-ray... Read more
Apple iOS 8.1 - The latest version of Ap...
The latest version of iOS can be downloaded through iTunes. Apple iOS 8 comes with big updates to apps you use every day, like Messages and Photos. A whole new way to share content with your family.... Read more
TechTool Pro 7.0.5 - Hard drive and syst...
TechTool Pro is now 7, and this is the most advanced version of the acclaimed Macintosh troubleshooting utility created in its 20-year history. Micromat has redeveloped TechTool Pro 7 to be fully 64... Read more
PDFKey Pro 4.0.2 - Edit and print passwo...
PDFKey Pro can unlock PDF documents protected for printing and copying when you've forgotten your password. It can now also protect your PDF files with a password to prevent unauthorized access and/... Read more
Yasu 2.9.1 - System maintenance app; per...
Yasu was originally created with System Administrators who service large groups of workstations in mind, Yasu (Yet Another System Utility) was made to do a specific group of maintenance tasks... Read more
Hazel 3.3 - Create rules for organizing...
Hazel is your personal housekeeper, organizing and cleaning folders based on rules you define. Hazel can also manage your trash and uninstall your applications. Organize your files using a... Read more
Autopano Giga 3.7 - Stitch multiple imag...
Autopano Giga allows you to stitch 2, 20, or 2,000 images. Version 3.0 integrates impressive new features that will definitely make you adopt Autopano Pro or Autopano Giga: Choose between 9... Read more

Latest Forum Discussions

See All

Swap Heroes (Games)
Swap Heroes 1.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0 (iTunes) Description: **Half price for a limited time only** Swap Heroes is a casual turn-based strategy adventure. Form a group of heroes and guide them... | Read more »
Ghost Blade (Games)
Ghost Blade 1.1 Device: iOS Universal Category: Games Price: $4.99, Version: 1.1 (iTunes) Description: Get the most outstanding 3D Action Game from App Store NOW! For those who dare pursue dreams. Masterpiece of Yu Shi Game ---China... | Read more »
Fiete – A Day on a Farm Review
Fiete – A Day on a Farm Review By Amy Solomon on October 21st, 2014 Our Rating: :: A MEMORABLE EXPERIENCEUniversal App - Designed for iPhone and iPad Fiete – A day on a farm in an interactive app for young children full of... | Read more »
Tilt to Live: Gauntlet’s Revenge is Almo...
Tilt to Live: Gauntlet’s Revenge is Almost Here Posted by Jessica Fisher on October 21st, 2014 [ permalink ] One Man Left has announced the official release date of Tilt to Live: Gauntlet’s Re | Read more »
Sago Mini Monsters Celebrates Halloween...
Sago Mini Monsters Celebrates Halloween with Fun Costumes and Special Treats. Posted by Jessica Fisher on October 21st, 2014 [ permal | Read more »
Inferno 2 Review
Inferno 2 Review By Andrew Fisher on October 21st, 2014 Our Rating: :: TWIN STICK GOODNESSUniversal App - Designed for iPhone and iPad With tight controls and awesome, stark visuals, Inferno 2 is loads of fun.   | Read more »
Clips Review
Clips Review By Jennifer Allen on October 21st, 2014 Our Rating: :: CONVENIENT PASTINGUniversal App - Designed for iPhone and iPad Making copying and pasting more powerful than usual, Clips is a great way to move stuff around.   | Read more »
MonSense Review
MonSense Review By Jennifer Allen on October 21st, 2014 Our Rating: :: ORGANIZED FINANCESiPhone App - Designed for the iPhone, compatible with the iPad Organize your finances with the quick and easy to use, MonSense.   | Read more »
This Week at 148Apps: October 13-17, 201...
Expert App Reviewers   So little time and so very many apps. What’s a poor iPhone/iPad lover to do? Fortunately, 148Apps is here to give you the rundown on the latest and greatest releases. And we even have a tremendous back catalog of reviews; just... | Read more »
Angry Birds Transformers Review
Angry Birds Transformers Review By Jennifer Allen on October 20th, 2014 Our Rating: :: TRANSFORMED BIRDSUniversal App - Designed for iPhone and iPad Transformed in a way you wouldn’t expect, Angry Birds Transformers is a quite... | Read more »

Price Scanner via MacPrices.net

Select MacBook Airs $100 off MSRP, free shipp...
B&H Photo has 2014 a couple of MacBook Airs on sale for $100 off MSRP. Shipping is free, and B&H charges NY sales tax only. They also include free copies of Parallels Desktop and LoJack for... 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
Strong iPhone, Mac And App Store Sales Drive...
Apple on Monday announced financial results for its fiscal 2014 fourth quarter ended September 27, 2014. The Company posted quarterly revenue of $42.1 billion and quarterly net profit of $8.5 billion... Read more
Apple Posts How-To For OS X Recovery
OS X 10.7 Lion and later include OS X Recovery. This feature includes all of the tools you need to reinstall OS X, repair your disk, and even restore from a Time Machine backup. OS X Recovery... Read more
Mac OS X Versions (Builds) Supported By Vario...
Apple Support has posted a handy resource explaining which Mac OS X versions (builds) originally shipped with or are available for your computer via retail discs, downloads, or Software Update. Apple... Read more
Deals on 2011 13-inch MacBook Airs, from $649
Daily Steals has the Mid-2011 13″ 1.7GHz i5 MacBook Air (4GB/128GB) available for $699 with a 90 day warranty. The Mid-2011 13″ 1.7GHz i5 MacBook Air (4GB/128GB SSD) is available for $649 at Other... Read more
2013 15-inch 2.0GHz Retina MacBook Pro availa...
B&H Photo has leftover previous-generation 15″ 2.0GHz Retina MacBook Pros now available for $1599 including free shipping plus NY sales tax only. Their price is $400 off original MSRP. B&H... Read more
Updated iPad Prices
We’ve updated our iPad Air Price Tracker and our iPad mini Price Tracker with the latest information on prices and availability from Apple and other resellers, including the new iPad Air 2 and the... Read more
Apple Pay Available to Millions of Visa Cardh...
Visa Inc. brings secure, convenient payments to iPad Air 2 and iPad mini 3as well as iPhone 6 and 6 Plus. Starting October 20th, eligible Visa cardholders in the U.S. will be able to use Apple Pay,... Read more
Textkraft Pocket – the missing TextEdit for i...
infovole GmbH has announced the release and immediate availability of Textkraft Pocket 1.0, a professional text editor and note taking app for Apple’s iPhone. In March 2014 rumors were all about... Read more

Jobs Board

Senior Event Manager, *Apple* Retail Market...
…This senior level position is responsible for leading and imagining the Apple Retail Team's global event strategy. Delivering an overarching brand story; in-store, Read more
*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
Project Manager / Business Analyst, WW *Appl...
…a senior project manager / business analyst to work within our Worldwide Apple Fulfillment Operations and the Business Process Re-engineering team. This role will work Read more
*Apple* Retail - Multiple Positions (US) - A...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
Position Opening at *Apple* - Apple (United...
…customers purchase our products, you're the one who helps them get more out of their new Apple technology. Your day in the Apple Store is filled with a range of Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.