TweetFollow Us on Twitter

Mar 93 Tips, Tidbits
Volume Number:9
Issue Number:3
Column Tag:Tips & Tidbits

Tips & Tidbits

By Neil Ticktin, Editor-in-Chief

This column is your opportunity to spread the word about little bits of information that you find out about. These tidbits can be programming related or they can be user tips that are particularly useful to programmers.

MacTech Magazine will pay $25 for every tip used, and $50 for the Tip of the Month. Or you can take your award in orders or subscriptions.

To submit a tip, send in a letter to the magazine. E-mail is our preferred method, but feel free to send something via the US Mail. See page 2 for all addresses. If you do send snail mail, enclose a printed copy and a disk copy of the letter so that it does not have to be retyped.

Tip of the Month

Writing code that will walk your array instead of using a standard loop to access the array elements will improve the speed of the code 40-400% depending on the compiler you use.

Standard array access:

FOR index := 1 TO kNumOfElements DO
    theArray[index] := someNumber;

Optimized access:
{--elementSize is the size of one array element. This is an example }
{  of an array of long integers, therefore SizeOf(LongInt)}
   elementSize := SizeOf(LongInt);
   elementPtr := LongIntPtr(arrayHandle^); {--Ptr to 1st array elmnt.}
   endArrayAddress := ORD4(elementPtr) + elementSize * kNumOfElements;
   WHILE ORD(elementPtr) < endArrayAddress DO
   BEGIN
   elementPtr^ := someNumber;  {--elementPtr^ accesses the array }
  {elements.  Increment the elementPtr }
  {to point to the next elt in the array.}
   elementPtr := LongIntPtr(ORD(elementPtr) + elementSize);
   END;

Essentially, you're forcing the compiler to generate more efficient code for your loop.

-- Marek Hajek, Reno, Nevada

Self Documenting Code

Do yourself a favor: write self-documented code. Have you ever looked over source code that makes no sense whatsoever? Worse yet, have you ever looked at your own code six months later and you can't make heads or tails of it?

Try self-documented code. This is where you name functions and variables so well that there is no mistake about what they do.

Consider a function you are writing that, say, strips off all the trailing space characters from a string. The WRONG names to give this function are "String1," "StrStrip," "FixString," to name a few. A far better name would be:

  remove_trailing_spaces_from_string

Yes, the name is long, but it pays off in a big way! If you came back a year later and looked at the code, well, what does this function do? Duh! Does it remove trailing spaces from a string, perhaps?!

The same rule applies to variable declarations. Instead of the ol' fashion "i," "k," etc., start naming your variables real English names that make sense. Example:

length_of_text instead if "i" or "len"

number_of_records instead of "r"

users_name instead of "UserStr" or "str"

You will find this system is worth far more than pages of (meaningless?) comments!

- Gar, DataPak Software

DrawPicture Bug

There is a crashing bug in DrawPicture that can happen when you draw pictures that contain very wide PixMaps. DTS has verified that this is a bug in QuickDraw (on machines with IIci ROMs or later running 7.0 or later. Currently, that means the IIci, IIfx, LC, IIsi, Classic II, PowerBook 140 and 170, and the Quadras all have this bug). Thanks to Forrest Tanaka for the following information.

The problem happens with pictures that contain direct PixMaps that have been compressed using run-length encoding. The bug is that DrawPicture allocates two times the rowBytes value of the direct PixMap on the stack without first checking to make sure that there’s enough space to grow the stack that big. For wide PixMaps, two times the rowBytes can be very big, and so the stack can easily overflow when you try to draw a picture that contains a wide PixMap.

A reasonable work-around for this bug is to increase the size of the area of memory that’s reserved for your stack, which is just above your application’s heap. By default, Color QuickDraw machines provide you with a 24K stack. The widest possible PixMap has 16K per row, so multiply that by two and you get 32K as a maximum amount of stack space DrawPicture needs to draw the direct PixMap. Add to this a lot of slop for all the other stuff that you’ll have on the stack when you call DrawPicture, and a 48K to 64K stack becomes reasonable, in my opinion at least.

Increasing the size of the area of memory for the stack is done by setting the address of the top of your heap farther down from where it is by default. The SetApplLimit routine lets you set this address, and the GetApplLimit routine gives you the current address of the top of your heap. To add space to the memory that’s set aside for your stack, you can use something like the following line of code:

SetApplLimit(Ptr(Ord4(GetApplLimit) - kAdditionalStackRequirements));

kAdditionalStackRequirements is the number of bytes of stack space you’d like above and over the default stack size. Make sure you call this before calling any other routine - before MaxApplZone, MoreMasters, and InitGraf.

If you want to find the existing size of area of memory for the stack, you can get the address of the bottom of the stack (the part that’s highest in memory) from the low-memory global called CurStackBase which is located at $0908. Subtract from this the return value of GetApplLimit, and you get the current size of the area of memory for your stack.

- Mike Scanlin, Mountain View, CA

Excerpt taken from DTS answer

The Easy way to store disks

I have looked far and wide for a way to store hundreds of diskettes. Most of the vendors want big dollars for custom disk holders. They look great in plastic or metal. Holding hundreds of disks though can get very expensive.

I have found that a three-drawer kit can be assembled easily. These kits are found in the hardware section of your local retailer. They are in the place where the furniture is sold for garages and children's rooms.

These drawers are made out of particle board and masonite. Each drawer is 4 1/2" high by 15" deep by 13" wide. I can put in 3 rows or 100 disks per row in these with plenty of room to thumb through the diskettes. That is 300 diskettes per drawer.

They can be assembled even by me or my kids in about 20 minutes. And instead of paying $100's to hold the disks, I have less than $25 into holding 900+ diskettes.

The disk holders are 15" High x 15" wide x 15" deep. They are manufactured by SturdiCraft, 2742 Homdale Rd., Klamath Falls, OR 97603 phone (503) 882-4406. They are available through Fred Meyer, Sears catalog sales, HomeBase and many local hardware stores. Or they are available direct from SturdiCraft for $34.30 including shipping and handling. Ask for Model S-350. Some assembly required.

- Bruce Kyle, Beaverton, Oregon

 
AAPL
$102.99
Apple Inc.
+0.52
MSFT
$44.38
Microsoft Corpora
-0.50
GOOG
$532.71
Google Inc.
+6.17

MacTech Search:
Community Search:

Software Updates via MacUpdate

Evernote 5.6.2 - Create searchable notes...
Evernote allows you to easily capture information in any environment using whatever device or platform you find most convenient, and makes this information accessible and searchable at anytime, from... Read more
OmniOutliner 4.1.3 - Organize your ideas...
OmniOutliner is a flexible program for creating, collecting, and organizing information. Give your creativity a kick start by using an application that's actually designed to help you think. It's... Read more
BBEdit 11.0 - Powerful text and HTML edi...
BBEdit is the leading professional HTML and text editor for the Mac. Specifically crafted in response to the needs of Web authors and software developers, this award-winning product provides a... Read more
Apple Security Update 2014-005 - For OS...
Apple Security Update is recommended for all users and improves the security of Mac OS X. For information on the security content of this update, please visit this website: http://support.apple.com/... Read more
EyeTV 3.6.6 - Watch and record TV on you...
EyeTV brings a rich TV experience to your Mac. Watch live TV on your Mac. Pause, rewind, and record whenever you want. EyeTV gives you powerful control over what you watch and how you watch it. Put... Read more
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
Command-C 1.1.5 - Clipboard sharing tool...
Command-C is a revolutionary app which makes easy to share your clipboard between iOS and OS X using your local WiFi network, even if the app is not currently opened. Copy anything (text, pictures,... 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

Latest Forum Discussions

See All

Pro Strategy Football 2014 (Games)
Pro Strategy Football 2014 2014.141001 Device: iOS Universal Category: Games Price: $4.99, Version: 2014.141001 (iTunes) Description: Take the proven strategy of the PSF franchise and add in Casual Play, improved graphics and... | Read more »
Super Glyph Quest (Games)
Super Glyph Quest 1.01 Device: iOS Universal Category: Games Price: $2.99, Version: 1.01 (iTunes) Description: Adventure is back Questers! Combine elemental glyphs together to cast powerful spells and vanquish adorable monsters in... | Read more »
Fighting Fantasy: Caverns of the Snow Wi...
Fighting Fantasy: Caverns of the Snow Witch 1.0 Device: iOS Universal Category: Games Price: $5.99, Version: 1.0 (iTunes) Description: Travel to Northern Allansia’s perilous Icefinger Mountains to defeat the wicked Snow Witch in this... | Read more »
Star Warfare 2: Payback Review
Star Warfare 2: Payback Review By Blake Grundman on October 22nd, 2014 Our Rating: :: ONE-TRICK PONYUniversal App - Designed for iPhone and iPad Unfortunately, it doesn’t take long for Star Warfare 2’s free-firing fun to turn into... | Read more »
TinType by Hipstamatic (Photography)
TinType by Hipstamatic 1.0 Device: iOS iPhone Category: Photography Price: $.99, Version: 1.0 (iTunes) Description: Create hauntingly beautiful, soul capturing portraits with TinType by Hipstamatic. Inspired by daguerreotypes,... | Read more »
The Latest Update for Heroes of Dragon A...
The Latest Update for Heroes of Dragon Age Introduces Daily PvE Challenges Posted by Ellis Spice on October 22nd, 2014 [ permalink ] | Read more »
Bee Brilliant Review
Bee Brilliant Review By Jennifer Allen on October 22nd, 2014 Our Rating: :: SAMEY MATCH-3Universal App - Designed for iPhone and iPad Want even more Match-3 gaming and fancy a bee based twist? Bee Brilliant is that game. Don’t... | Read more »
A New Trailer has Been Revealed for Epic...
A New Trailer has Been Revealed for Epic of Kings Posted by Jessica Fisher on October 22nd, 2014 [ permalink ] Dead Mage Inc. has released a new, action-packed trailer for the upcoming Epic of Kings. | Read more »
Find the Line Review
Find the Line Review By Campbell Bird on October 22nd, 2014 Our Rating: :: INSLIDE THE LINESUniversal App - Designed for iPhone and iPad Tease out beautiful line drawings in this unique, free-to-play puzzle game.   | Read more »
Things Get Magical in The Sims FreePlay...
Things Get Magical in The Sims FreePlay with a New Halloween Update Posted by Ellis Spice on October 22nd, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »

Price Scanner via MacPrices.net

Save with Best Buy’s College Student Deals
Take an additional $50 off all MacBooks and iMacs at Best Buy Online with their College Students Deals Savings, valid through November 1st. Anyone with a valid .EDU email address can take advantage... Read more
iPad Air 2 & iPad mini 3 Best Tablets Yet...
The new iPads turned out to be pretty much everything I’d been hoping for and more than I’d expected.”More” particularly in terms of a drinking-from-a-firehose choice of models and configurations,... Read more
Drafts 4 Reinvents iOS Productivity App
N Richland Hills, Texas based Agile Tortoise has announced the release of Drafts 4 for iPhone and iPad. Drafts is a quick capture note taking app with flexible output actions. Drafts 4 scales from... Read more
AT&T accepting preorders for new iPads fo...
AT&T Wireless is accepting preorders for the new iPad Air 2 and iPad mini 3, cellular models, for $100 off MSRP with a 2-year service agreement: - 16GB iPad Air 2 WiFi + Cellular: $529.99 - 64GB... Read more
Apple offering refurbished Mac Pros for up to...
The Apple Store is offering Apple Certified Refurbished 2013 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
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

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.