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

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

PopChar 7.1 - Floating window shows avai...
We're also selling a 5-license family pack for only $25.99! PopChar helps you get the most out of your font collection. With its crystal-clear interface, PopChar X provides a frustration-free way to... Read more
BBEdit 11.1.1 - Powerful text and HTML e...
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
Picasa 3.9.139 - Organize, edit, and sha...
Picasa and Picasa Web Albums allows you to organize, edit, and upload your photos to the Web from your computer in quick, simple steps. Arrange your photos into folders and albums and erase their... Read more
Mac DVDRipper Pro 5.0.5 - Copy, backup,...
Mac DVDRipper Pro is the DVD backup solution that lets you protect your DVDs from scratches, save your batteries by reading your movies from your hard disk, manage your collection with just a few... Read more
NetShade 6.2 - Browse privately using an...
This promotion is for NetShade and 1 year of Proxy and VPN services NetShade is an anonymous proxy and VPN app+service for Mac. Unblock your Internet through NetShade's high-speed proxy and VPN... Read more
CrossOver 14.1.3 - Run Windows apps on y...
CrossOver can get your Windows productivity applications and PC games up and running on your Mac quickly and easily. CrossOver runs the Windows software that you need on Mac at home, in the office,... Read more
Little Snitch 3.5.3 - Alerts you about o...
Little Snitch gives you control over your private outgoing data. Track background activity As soon as your computer connects to the Internet, applications often have permission to send any... Read more
OmniGraffle Pro 6.2.3 - Create diagrams,...
OmniGraffle Pro helps you draw beautiful diagrams, family trees, flow charts, org charts, layouts, and (mathematically speaking) any other directed or non-directed graphs. We've had people use... Read more
OmniFocus 2.2 - GTD task manager with iO...
OmniFocus helps you manage your tasks the way that you want, freeing you to focus your attention on the things that matter to you most. Capturing tasks and ideas is always a keyboard shortcut away in... Read more
1Password 5.3.2 - Powerful password mana...
1Password is a password manager that uniquely brings you both security and convenience. It is the only program that provides anti-phishing protection and goes beyond password management by adding Web... Read more

MooVee - Your Movies Guru (Entertainmen...
MooVee - Your Movies Guru 1.0 Device: iOS iPhone Category: Entertainment Price: $1.99, Version: 1.0 (iTunes) Description: MooVee helps you effortlessly manage your movies, on your iPhone. | Read more »
Geometry Wars 3: Dimensions (Games)
Geometry Wars 3: Dimensions 1.0.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.0 (iTunes) Description: Enjoy the next chapter in the award-winning Geometry Wars franchise and enjoy stunning, console-quality... | Read more »
CHAOS RINGS Ⅲ (Games)
CHAOS RINGS Ⅲ 1.0.0 Device: iOS Universal Category: Games Price: $19.99, Version: 1.0.0 (iTunes) Description: The newest addition to the popular smartphone RPG series is finally here! ・CHAOS RINGS Overview | Read more »
The Popular Insight Series of Travel Gui...
Getting around in a country when you can't understand the primary language can be tough. Fortunately there are several options available to help wold travellers with the important stuff like giving directions to a cab driver or asking where the... | Read more »
Desktop Dungeons is Now on the iPad Desp...
Desktop Dungeons has been a well-loved roguelike on PC for quite some time, and now it's finally available for the iPad! Just the iPad, though. Sorry iPhone users. [Read more] | Read more »
Moleskine Timepage – Calendar for iCloud...
Moleskine Timepage – Calendar for iCloud, Google & Exchange 1.0 Device: iOS iPhone Category: Productivity Price: $4.99, Version: 1.0 (iTunes) Description: The most elegant calendar for your pocket and wrist, Timepage is a... | Read more »
QuizUp Gets Social in its New Update
Plain Vanilla Corp has released a new and improved version of their popular trivia game, QuizUp. The app now emphasizes social play so you can challenge friends from all over the world. [Read more] | Read more »
The Deep (Games)
The Deep 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: Swipe Controls Delve into the deep in this retro rogue-like! Swipe to move your diver around and keep away from the enemies as you... | Read more »
Sproggiwood (Games)
Sproggiwood 1.2.8 Device: iOS Universal Category: Games Price: $9.99, Version: 1.2.8 (iTunes) Description: Sproggiwood was developed for devices with at least 1GB of RAM. We recommend you only download Sproggiwood if your device... | Read more »
Battle of Gods: Ascension (Games)
Battle of Gods: Ascension 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: TURN-BASED TACTICAL COMBATFight tactical battles against the forces of Hades! In Battle of Gods: Ascension you play... | Read more »

Price Scanner via MacPrices.net

Apple refurbished 2014 13-inch Retina MacBook...
The Apple Store has Apple Certified Refurbished 2014 13″ Retina MacBook Pros available for up to $400 off original MSRP, starting at $979. An Apple one-year warranty is included with each model, and... Read more
What Would the ideal Apple Productivity Platf...
For the past four years I’ve kept a foot in both the Mac and iPad camps respectively. my daily computing hours divided about 50/50 between the two devices with remarkable consistency. However, there’... Read more
PageMeUp 1.2.1 Ten Dollar Page Layout Applica...
Paris, France-based Softobe, an OS X software development company, has announced that their PageMeUp v. 1.2.1, is available on the Mac App Store for $9.99. The license can be installed on up to 5... Read more
Eight New Products For USB Type-C Application...
Fresco Logic, specialists in advanced connectivity technologies and ICs, has introduced two new product families targeting the Type-C connector recently introduced across a number of consumer... Read more
Scripps National Spelling Bee Launches Buzzwo...
Scripps National Spelling Bee fans can monitor the action at the 2015 Spelling Bee with the new Buzzworthy app for iOS, Android and Windows mobile devices. The free Buzzworthy app provides friendly... Read more
13-inch 2.5GHz MacBook Pro on sale for $120 o...
B&H Photo has the 13″ 2.5GHz MacBook Pro on sale for $979 including free shipping plus NY sales tax only. Their price is $120 off MSRP, and it’s the lowest price for this model (except for Apple’... Read more
27-inch 3.3GHz 5K iMac on sale for $1899, $10...
B&H Photo has the new 27″ 3.3GHz 5K iMac on sale for $1899.99 including free shipping plus NY tax only. Their price is $100 off MSRP. Read more
Save up to $50 on iPad Air 2, NY tax only, fr...
B&H Photo has iPad Air 2s on sale for up to $50 off MSRP including free shipping plus NY sales tax only: - 16GB iPad Air 2 WiFi: $469 $30 off - 64GB iPad Air 2 WiFi: $549.99 $50 off - 128GB iPad... Read more
Updated Mac Price Trackers
We’ve updated our Mac Price Trackers with the latest information on prices, bundles, and availability on systems from Apple’s authorized internet/catalog resellers: - 15″ MacBook Pros - 13″ MacBook... Read more
New 13-inch 2.9GHz Retina MacBook Pro on sale...
B&H Photo has the 13″ 2.9GHz/512GB Retina MacBook Pro on sale for $1699.99 including free shipping plus NY tax only. Their price is $100 off MSRP, and it’s the lowest price for this model from... Read more

Jobs Board

Program Manager, *Apple* Community Support...
**Job Summary** Apple Support Communities ( discussions. apple .com) helps customers get the most from their Apple products and services by providing access to Read more
Senior Data Scientist, *Apple* Retail - Onl...
**Job Summary** Apple Retail - Online sells Apple products to customers around the world. In addition to selling Apple products with unique services such as iPad Read more
*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* Watch SW Application Project Manager...
**Job Summary** The Apple Watch software team is looking for an Application Engineering Project Manager to work on new projects for Apple . The successful candidate Read more
Engineering Manager for *Apple* Maps on the...
…the Maps App Team get to take part in just about any new feature in Apple Maps, often contributing a majority of the feature work. In our day-to-day engineering work, we Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.