TweetFollow Us on Twitter

Dumb bugs
Volume 9
Number 11
Column TagsState of the Industry

Glenn’s Philosophy on Programming

Tricks to avoid wasting time on “dumb” bugs

By G. Weinreb, Somerville, Massachusetts

The most important thing in software development is that the programmer must love their code. If the programmer does not love his code, coding becomes a chore as opposed to a joy, causing code quality, coding productivity, and the programmer's mental state to degrade. In order for a programmer to love their code, ALL of the following must be true:

• The code must be well organized with specific functionality localized to one area, as opposed to appearing multiple times.

• ALL routines must be extremely well tested.

• ALL routines must be extremely well documented.

• Many routines must contain defensive code, especially the low level ones.

• The programmer must have a decent machine with which to develop.

• The programmer must have a decent development environment and a decent understanding of how to use it.

• The programmer must have a good debugger. Working with complex black boxes, into which you cannot peer, is a hell that I would not wish upon even the fiercest of competitors.

The fundamental principle behind programming is that each issue must be localized to one area (e.g. one function); and that this one area do it's job extremely well (i.e. employ defensive code, include outstanding documentation, and be extremely well tested). And then all the other routines are to rely on ONE to implement the specific functionality. If similar functionality is copied and implemented in different places, then the programmer has less time to make each copy solid. Unsolid (non defensive, non documented, non tested) code leads to the following scenario:

A programmer is programming one function that calls another, and finds that the called one is not working well. So the programmer stops what he/she is doing and goes to fix the lower level routine. Now, if it is undocumented, the programmer needs to read each line, figure out what it's doing, and then document it - which can take more time than coding the thing from scratch. Therefore, undocumented code is in a sense disposable - you use it once and then throw it away and get another (like a Kleenex) when you need to change it. So the poor programmer documents the routine, tests it and makes it solid. But then we find that many other routines call this function, and our making it solid has changed it a little, causing it to not work for some of it's other callers. Subsequently, the programmer must fight to make it work in all cases - which requires coding in other areas - which can lead to new frontiers. And much time goes by while the poor programmer has accomplished very little on the original routine. And subsequently, they find it very hard to love their code.

So,

• Code MUST be well documented, which includes:

+ function headers for all functions

+ descriptive headers for each file

+ descriptions of passed arguments

+ documentation in the code which describes what it does and how it does it

• Code must be thoroughly tested because the devil is in the details and the details are what will bite you. Subsequently, you've got to DIG, DIG, DIG to uncover those subtle little problems. And the key to this is to have the confidence that they exist, else you will not dig for them - SO ASSUME THEY EXIST AND DIG, DIG, DIG.

• Code MUST be defensive in order to get ahead of the bugs. Defensive coding entails looking for problems and showing an alert if one is found. Several examples:

a) Arguments passed to low level routines (i.e. the one's called by many other routines) are checked if doing development. A global variable, 'gDevelopment', is set TRUE when doing development, and at any time, the user can press an Option key to toggle the state of 'gDevelopment' TRUE/FALSE. 'gDevelopment' is typically used in the following way:

/* 1 */

void SetUserItem (
 DialogPtr dialog, //ptr to dialog box
 short itemNr,   //item's DITL #
 ProcPtr doDraw) //procedure pointer for                       
 //user  DITL item
{
 if (gDevelopment)  {// if doing develop...
 if (IfPtrIsNullOrBadYell ((Ptr) dialog, 1))                   return;
 // test for null or bad ptr
 if (IfDitlNrIsBadYell (itemNr, TRUE)) return;           // test for 
bad ditl #
 if (IfPtrIsNullOrBadYell ((Ptr) doDraw, 1))
 return;// test for null or bad ptr
 }
 body .....
 body .....
}

Subsequently, if there is trouble, the programmer knows about the problem before it causes harm. And bugs can cause harm in a manner which is not obvious and/or a manner which does not lead the programmer to the bad code (e.g. a bug in area A destroys memory in area B, which crashes 100 mouse clicks latter). Defensive coding is like being at the window with a shotgun when the burglar climbs in - "Hey, what the hell do you think you're doing?". Programmers must get ahead of bugs, not behind, in order to love their code.

Someone playing devil's advocate might say, "Doesn't it take time to install defensive code and doesn't it slow your program?". It does take some time to implement, yet not much since it involves mindless cut/copy/paste of similar existing code fragments. The time for the processor to check for 'gDevelopment' TRUE is less than a microsecond (for perspective, HLock() costs 121µs on a Mac IIcx). Subsequently, adding "if (gDevelopment)" increases execution time by only a tiny amount. Freeing the programmer from fighting bugs will give him/her more time to optimize code - which will save orders of magnitude more execution time.

b) One can use macros to add defensive coding to toolbox routines. e.g.

/* 2 */

 #define HLock_(h) \
 \
 if (gDevelopment) { \
 if (CheckHandle((Handle) h, TRUE, TRUE))    \
 HLock((Handle) h);\
 } \
 else if (h){    \
 HLock((Handle) h);\
 }

This simple little macro has saved my life on a number of occasions.

c) We will define the phrase "memory problem" as code which writes to memory where it should not, and possibly causes trouble in an unrelated area and/or in an intermittent way - both of which are infamous to programmers. In the case of a "memory problem", one must have a strategy for dealing with it (other than fumbling around and saying, "Gee's, this really IS a tough one."). One technique is to use a global, 'gShakeLikeHell', which is toggled TRUE/FALSE by pressing an Option key (it is always set to FALSE when you first launch the application), and a macro defined as follows:

/* 3 */

#define SHAKELIKEHELLIFSHAKING\
 \
 if (gShakeLikeHell) \
 ShakeLikeHellifShaking();

ShakeLikeHellifShaking() compacts the heap, creates handles, disposes of handles, and tests existing data structures. If you have an intermittent or nebulous bug, the best response is to install the SHAKELIKEHELLIFSHAKING macro throughout your code under development, run the application, and press the Option key to turn it on. Chances are you will crash, or see the problem sooner (i.e. closer to the bad code). Ideally you would like to isolate the problem area between 2 SHAKELIKEHELLIFSHAKING macros (which is a mechanism which identifies if the problem does or does not originate from a specified range of code). After installing the macro, you can leave it in your code - it cost less than a microsecond. [Except for the time spent in the ShakeLikeHellifShaking routine. - Tech. Ed]. Installing this macro may seem silly, yet I can attest it has worked beautifully on many occasions - encouraging me to love my code.

 
AAPL
$100.75
Apple Inc.
+0.64
MSFT
$46.36
Microsoft Corpora
-0.08
GOOG
$577.36
Google Inc.
+1.00

MacTech Search:
Community Search:

Software Updates via MacUpdate

QuickBooks 2015 16.0.0.1352 R1 - Financi...
QuickBooks 2015 helps you manage your business easily and efficiently. Organize your finances all in one place, track money going in and out of your business, and spot areas where you can save.... Read more
Mac DVDRipper Pro 5.0.1 - 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
Apple OS X bash Update 1.0 - Fix for sec...
The OS X bash Update fixes a security flaw in the bash UNIX shell on OS X 10.9.5 (also on OS X 10.8 and 10.7 [see Related Links below]). OS X 10.9.5 or later Downloads for OS X 10.8 and OS X 10.7 in... Read more
SyncTwoFolders 2.0.5 - Syncs two user-sp...
SyncTwoFolders simply synchronizes two folders. It supports synchronization across mounted network drives and it is a possibility to run a simulation showing in a log what will be done. Please visit... Read more
FinderPop 2.5.7 - Classic Mac utility, n...
FinderPop is a Universal preference pane that extends OS X's contextual menus using a FinderPop Items folder much as the Apple Menu Items folder used to do for the Apple menu. It has other features... Read more
VueScan 9.4.45 - Scanner software with a...
VueScan is a scanning program that works with most high-quality flatbed and film scanners to produce scans that have excellent color fidelity and color balance. VueScan is easy to use, and has... Read more
LibreOffice 4.3.2.2 - Free Open Source o...
LibreOffice is an office suite (word processor, spreadsheet, presentations, drawing tool) compatible with other major office suites. The Document Foundation is coordinating development and... Read more
calibre 2.4 - Complete e-library managem...
Calibre is a complete e-book library manager. Organize your collection, convert your books to multiple formats, and sync with all of your devices. Let Calibre be your multi-tasking digital... Read more
Default Folder X 4.6.9b1 - Enhances Open...
Default Folder X attaches a toolbar to the right side of the Open and Save dialogs in any OS X-native application. The toolbar gives you fast access to various folders and commands. You just click... Read more
Beamer 2.0.4 - Stream any movie file fro...
Beamer streams to your Apple TV.... Plays any movie file - Just like the popular desktop movie players, Beamer accepts all common formats, codecs and resolutions. AVI, MKV, MOV, MP4, WMV, FLV. To... Read more

Latest Forum Discussions

See All

apeFilter (Music)
apeFilter 1.0 Device: iOS Universal Category: Music Price: $6.99, Version: 1.0 (iTunes) Description: | Read more »
Shred It! Review
Shred It! Review By Jennifer Allen on September 30th, 2014 Our Rating: :: GORGEOUS BUT BASICUniversal App - Designed for iPhone and iPad It might look lovely, but Shred It! is a pretty shallow endless runner/snowboarding game.   | Read more »
It Came From Canada: Angry Birds: Transf...
Anyone afraid that throwing Transformers into the Angry Birds mix would result in a Michael Bay-level of childhood pillaging can rest easy. While Rovio’s famous fowls may be a 21st century staple, Angry Birds: Transformers wears its affection for... | Read more »
Galaxy Trucker Review
Galaxy Trucker Review By Rob Thomas on September 30th, 2014 Our Rating: :: IN FOR THE LONG HAULiPad Only App - Designed for the iPad We got a great big convoy, rockin’ through the night… the endless night of outer space, that is.... | Read more »
Moon and Sun – children’s book Review
Moon and Sun – children’s book Review By Amy Solomon on September 30th, 2014 Our Rating: Moon and Sun is a fable-like children’s book with lush illustrations.   Developer: Marcio Monteiro Price: $3.99 Version: 1.0 App Reviewed on... | Read more »
Kairosoft Finally Brings The Pyraplex to...
Kairosoft Finally Brings The Pyraplex to iOS Posted by Jessica Fisher on September 30th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Yeti’s Parole Officer Review
Yeti’s Parole Officer Review By Jennifer Allen on September 30th, 2014 Our Rating: Universal App - Designed for iPhone and iPad Yeti’s Parole Officer proves that looks aren’t everything in this entertaining, if plain, piece of... | Read more »
Record Keeper and World Wide Words – Two...
Record Keeper and World Wide Words – Two New Final Fantasy Games Arrive on iOS in Japan Posted by Ellis Spice on September 30th, 2014 [ permalink ] | Read more »
iPollute Review
iPollute Review By Nadia Oxford on September 30th, 2014 Our Rating: :: iPOLLUTE, uPOLLUTEUniversal App - Designed for iPhone and iPad iPollute is a delightful-looking pollution simulator, though it’s a bit light on “game” content... | Read more »
This Week at 148Apps: September 22-26, 2...
Your Source For The Latest App Reviews   | Read more »

Price Scanner via MacPrices.net

MacBook Airs on sale for $100 off MSRP, start...
Best Buy has the new 2014 MacBook Airs on sale for $100 off MSRP on their online store. Choose free home shipping or free local store pickup (if available). Prices valid for online orders only, in-... Read more
Apple Releases OS X Mavericks bash Update 1.0...
Apple has released a patch update for OS X Mavericks users to address the recently-detected “Shellshock” security bug in BSD UNIX’s bash shell. Apple says only a few Mac users who had manually... Read more
Pivotal Payments Ready for Apple Pay – FlexPo...
Pivotal Payments, a provider of merchant services and global payment processing solutions, has announced its proprietary FlexPoint platform will support credit and debit transactions through Apple’s... Read more
iStabilizer Announces Tabarm — First Friction...
iStabilizer, a specialist in universal lightweight compact tripods, steady cams, dollies, mounts, and remotes for smartphones, tablets, and cameras, announced today the iStabilizer tabArm, the first... Read more
IStabilizer Flex Smartphone Tripod Wins Usa T...
iStabilizer, a specialist in universal lightweight compact tripods, steady cams, and other products for smartphones, tablets, and cameras, has announced today that its iStabilizer Flex smartphone... Read more
13-inch 2.8GHz Retina MacBook Pro on sale for...
B&H Photo has the new 2014 13″ 2.8GHz Retina MacBook Pro on sale for $1699.99 including free shipping plus NY sales tax only. They’ll also include free copies of Parallels Desktop and LoJack for... Read more
15-inch Retina MacBook Pros on sale for up to...
B&H Photo has the new 2014 15″ Retina MacBook Pros on sale for up to $150 off MSRP. Shipping is free, and B&H charges NY sales tax only. They’ll also include free copies of Parallels Desktop... Read more
Get Down to Business On Your iPad With Free N...
Utah based Poem LLC has introduced Nexticy 1.0, a full-featured, affordable (Free) forms application for iPad. Nexticy makes it ‘way easy’ to create, store, retrieve and analyze paper-like forms of... Read more
13-inch Retina MacBook Pros on sale for $100...
Best Buy has 13-inch 2.6GHz Retina MacBook Pros on sale for $100 off MSRP on their online store. Choose free shipping or free local store pickup (if available). Prices are for online orders only, in-... Read more
Reports Outline Claimed 12-Inch Macbook Air D...
Blogger Jack March says that according to information he’s received from an anonymous “source familiar with Apple’s plans,” the next-generation MacBook Air will launch in mid-2015 and be available... Read more

Jobs Board

*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the 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
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
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.