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.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Typinator 7.3 - Speedy and reliable text...
Typinator turbo-charges your typing productivity. Type a little. Typinator does the rest. We've all faced projects that require repetitive typing tasks. With Typinator, you can store commonly used... Read more
coconutBattery 3.6.4 - Displays info abo...
With coconutBattery you're always aware of your current battery health. It shows you live information about your battery such as how often it was charged and how is the current maximum capacity in... Read more
iShowU Instant 1.2.0 - Full-featured scr...
iShowU Instant gives you real-time screen recording like you've never seen before! It is the fastest, most feature-filled real-time screen capture tool from shinywhitebox yet. All of the features you... Read more
TrailRunner 3.8.1840 - Route planning fo...
TrailRunner is the perfect companion for runners, bikers, hikers, and all people wandering under the sky. Plan routes on a geographical map. Import GPS or workout recordings and journalize your... Read more
NetShade 7.1 - Browse privately using an...
NetShade is an anonymous proxy and VPN app+service for Mac. Unblock your Internet through NetShade's high-speed proxy and VPN servers spanning seven countries. NetShade masks your IP address as you... Read more
1Password 6.8.2 - 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
ClamXav 2.15.1 - Virus checker based on...
ClamXav is a popular virus checker for OS X. I have been working on ClamXav for more than 10 years now, and over those years, I have invested a huge amount of my own time and energy into bringing... Read more
NetShade 7.1 - Browse privately using an...
NetShade is an anonymous proxy and VPN app+service for Mac. Unblock your Internet through NetShade's high-speed proxy and VPN servers spanning seven countries. NetShade masks your IP address as you... Read more
1Password 6.8.2 - 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
TrailRunner 3.8.1840 - Route planning fo...
TrailRunner is the perfect companion for runners, bikers, hikers, and all people wandering under the sky. Plan routes on a geographical map. Import GPS or workout recordings and journalize your... Read more

Thimbleweed Park (Games)
Thimbleweed Park 1.0.0 Device: iOS Universal Category: Games Price: $9.99, Version: 1.0.0 (iTunes) Description: A brand new adventure game from Ron Gilbert and Gary Winnick, creators of the classics Monkey Island and Maniac Mansion!... | Read more »
The best simulation games on mobile
There's nothing like a good sim -- from the seemingly ridiculous to the incredibly mundane, you can be there's a simulation game out there for your every whim. [Read more] | Read more »
INKS guide - how to create works of pinb...
INKS puts a clever new spin on everyone's favorite classic arcade game, pinball. The core mechanics are the same -- keep a little ball pinging around the board for as long as possible without letting it fall into the precarious holes in the board.... | Read more »
Warbands: Bushido (Games)
Warbands: Bushido 1.0 Device: iOS Universal Category: Games Price: $3.99, Version: 1.0 (iTunes) Description: Warbands:Bushido is a miniatures board game with cards, miniatures, dice and beautiful terrains to fight on, with both... | Read more »
The best mobile games like Divinity: Ori...
Divinity: Original Sin 2 launched this week to the excitement of RPG fans everywhere. The game, which derives a lot of of its story and mechanics from old-school isometric RPGs and Dungeons & Dragons, has unseated PlayerUnknown's... | Read more »
Iron Marines guide - beginner tips and t...
Iron Marines is a brilliant RTS title that feels a bit like Starcraft. It's got a sci-fi setting and some of the most spectacular strategy mechanics we've seen in mobile games to date. With that said, the RTS genre can be a bit tricky to break... | Read more »
The best new games we played this week -...
The work week can be tough, but on the bright side, it's almost overandthere are bunches of brand new games to try out this weekend. This week definitely makes up for last week's sleepiness ten-fold. We've got one of the finest RTS game on mobile... | Read more »
Through the Ages (Games)
Through the Ages 1.0.60 Device: iOS Universal Category: Games Price: $9.99, Version: 1.0.60 (iTunes) Description: The offical adaptation of Vlaada Chvátil’s strategy classic, the second best board game ever by Board Game Geek website... | Read more »
The best RTS games like Iron Marines
Iron Marines launched today, and it's definitely taking the mobile gaming world by storm. In fact, our reviews editor Campbell says it's "quite possibly the best real-time strategy game on the App Store." If you're looking for more real-time... | Read more »
Uri: The Sprout of Lotus Creek (Games)
Uri: The Sprout of Lotus Creek 1.0.5 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0.5 (iTunes) Description: Published by Fantastic Games IntroductionDesigned by DreamTree Games(An indie games studio in Malaysia ) | Read more »

Price Scanner via MacPrices.net

Apple refurbished 128GB iPhone 6s and 6s Plus...
Apple has Certified Refurbished 128GB iPhone 6s and 6s Plus’ available for up to $100 off the price of new models. Space Gray, Silver, Gold, and Rose Gold models are available. Each phone comes... Read more
13-inch 2.3GHz Silver MacBook Pros on sale fo...
B&H Photo has 2017 13″ 2.3GHz Silver MacBook Pros in stock today and on sale for $100 off MSRP, each including free shipping plus NY & NJ sales tax only: – 13-inch 2.3GHz/128GB Silver... Read more
12-inch 64GB iPad Pros available for $749, $5...
MacMall has 12″ 64GB iPad Pros on sale for $749 including free shipping. Their price is $50 off MSRP. Read more
Sunday deal: 10-inch 256GB iPad Pros for $699...
MacMall has 10.5″ 256GB WiFi iPad Pros on sale today for $699 including free shipping. That’s $100 off MSRP. Read more
2017 12-inch 1.2GHz Retina MacBooks on sale f...
Amazon has 2017 12″ 1.2GHz Retina MacBooks on sale for $100 off MSRP. Shipping is free: 12″ 1.2GHz Space Gray MacBook: $1199 $100 off MSRP 12″ 1.2GHz Silver MacBook: $1199 $100 off MSRP 12″ 1.2GHz... Read more
Apple Certified Refurbished 21-inch and 27-in...
Apple is now offering a full line of Certified Refurbished 2017 21″ and 27″ iMacs. Models start at $1019 and range up to $350 off original MSRP. Apple’s one-year warranty is standard, and shipping is... Read more
Apple now offering Certified Refurbished 2017...
Apple is now offering Certified Refurbished 2017 12″ Retina MacBooks for up to $240 off the cost of new models. Apple will include a standard one-year warranty with each MacBook, and shipping is free... Read more
Steve Jobs’ Democratization Of The Smartphone...
Can it be only ten years since Steve Jobs introduced the world to the iPhone and changed everything? Jobs and Apple didn’t invent the smartphone. IBM designed a primitive one called SIMON in 1992,... Read more
Save up to $200 on 2017 Apple iMacs
B&H Photo has 2017 21-inch and 27-inch iMacs in stock and on sale for $100-$200 off MSRP including free shipping. B&H charges sales tax in NY & NJ only: – 27″ 3.8GHz iMac (MNED2LL/A): $... Read more
AnyTrans 6.0 Lets Android Users Switch to New...
iMobie has announced the release of their flagship product AnyTrans V6.0 with free iOS Mover. Available for both Mac and Windows, now users are completely free to transfer most types of Android data... Read more

Jobs Board

*Apple* Solutions Consultant - Apple Inc. (U...
…about helping others on a team while also delighting customers? As an Apple Solutions Consultant (ASC), you will discover customers needs and help connect them Read more
Software/Data Engineer, *Apple* Media Produ...
Job Summary Apple Media Products is the team behind the App Store, Apple Music, iTunes, and many other high profile products on iPhone, Mac and AppleTV. Our Data Read more
SW Engineer , *Apple* Media - Apple Inc. (U...
Job Summary Our team is responsible for exposing Apple Media content and services to the world, and building the infrastructure for next generation internal and Read more
*Apple* Data Center Site Selection and Strat...
Job Summary As Apple 's products and services scale the globe, the Data Center Affairs team works behind the scenes to secure infrastructure for Apple 's data Read more
*Apple* Professional Learning Specialist - A...
Job Summary The Apple Professional Learning Specialist is a full-time position for one year with Apple in the Yuma, AZ area. This position requires a high Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.