Worm with Glasses

Coding • DevOps • Personal

Jan 16, 2006

Programmer's Library

Every working programmer or software developer ought to have a large personal library of books they consider essential–these books are mine. My list started off being very language heavy (mostly Perl), but as I’ve gotten older (and gained more experience) I’ve gravitated towards broader topics in software development.

Programming

Languages

ASP.NET

C/C++

Clojure

Perl

Regular Expressions

Ruby

Development

Foundation/Theory

Hardware

System Administration

Graphic Design/Usability

Others…

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Jan 16, 2006

Reading List

I try to read a variety of books. In the past the local library was down the street from where I lived, but now I prefer reading ebooks (either purchased or borrowed.)

There is a large gap where no books were recorded while the site was offline: a regret as I know I read during those periods.

(If you’re a programmer or developer, check out my collection of programming books.)

January 2024

December 2023

November 2023

October 2023

September 2023

July 2023

April 2023

February 2023

January 2023

December 2022

November 2022

October 2022

September 2022

August 2022

June 2022

May 2022

December 2021

September 2021

August 2021

May 2021

April 2021

March 2021

February 2021

January 2021

August 2020

May 2020

August 2019

June 2019

February 2019

January 2019

October 2018

September 2018

August 2018

July 2018

June 2018

May 2018

April 2018

March 2018

September 2017

August 2017

July 2017

December 2016

November 2016

July 2016

December 2009

May 2009

February 2007

September 2006

June 2006

February 2006

January 2006

December 2005

November 2005

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Dec 14, 2005

Telecommuting to Work Now

For the past week I’ve been employed as a Perl web application developer at chaffee::interactive. It’s been an interesting week. I’m now starting to get the hang of the development environment. A lot of the code is older, so I’ve been spending most of my time updating the code.

It’s a great job, and I love the fact that I telecommute to work. It’s especially nice when I wake up in the morning and see a foot of snow.

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Dec 2, 2005

Wormbytes::CGI::Application

I’ve done a lot of CGI application programming. Over the years I’ve developed a CGI::Application base class that I derive my applications from. I’ve called my Perl module WormBytes::CGI::Application since it derives from CGI::Application. It brings in all the modules I normally use in my CGI programming.

In addition to the required modules, I’ve extended the class to handle session management. There is also rudimentary support for user management in the base code. Nothing fancy, but enough to do simple log-in style applications. It can be easily extended in sub-classes if needed.

The session management code uses a UUID numbering system. The idea is that each session ID needs a unique ID, but the IDs do not need to be random. Uniqueness is more important. To ensure that sessions can not be hi-jacked, an additional HMAC cookie is included with the session ID cookie. This HMAC includes a random number stored in the session on the server plus a hash of information from the client. The client information is not required, but it does help if the information is present. Because of the random key that’s used in the hash it is impossible to guess what the HMAC will be. It is checked at the beginning of each request and modified at the end of each request. Therefore, the HMAC is constantly changing and is constantly validated. In this, the base class, an invalid session causes the system to log the user out.

There are also certain helper functions like tt_pre_process() that adds certain objects and variables to all templates. cgi_untaint() creates a CGI::Untaint object for later use. Finally, redirect_url() simply redirects the client to a new location.

I find this module to be a great base for all my CGI applications.

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Dec 2, 2005

Perl Programming Sample Work

I had an interview for a Perl programming position the other day, but I got stuck on their request for sample code showing my Perl programming skills. I have done Perl programming for eight years, but their requirements for sample work did not seem to match anything I had done. I finally found something I could show, but I wasn’t entirely pleased with it. Therefore, I posted a meditation to Perl Monks asking how they would Show Sample Source Code without Modules

Maybe my fellow monks can offer some suggestions for next time. (All though, I would really like to get the job I interviewed for.)

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Dec 2, 2005

Emacs Lisp

Emacs is my editor of choice, and like most people who use Emacs I have customized it to suite my personal taste. I have included copies of my customizations so that others may build on what I’ve created, or simply have a more pleasant working environment.

Lisp Source

emacs.el

This is my main .emacs file. It contains the bulk of the customizations, but it does include a few other features and functions that other people may find useful. Some of the code is written by me, and other parts I’ve found on the net.

planner-config.el

To help me manage my time and my projects I have turned to the plannel-el (PlannerMode) major mode. Since I have worked as a independent IT consultant, I often need to track the number of hours I work on projects for various clients. I have customized and extended planner-el to allow me to clock in and out of a task. Upon clock-out the system will automatically prompt me for a description of what I did during the clocked-in time, and then write a note on the task page for the project detailing the amount of time I spent, and allowing me to classify the work performed. I then have a separate Perl script that takes the raw task pages and produces an invoice. I think it’s a very slick setup.

pic-asm-mode.el

I have done a lot of firmware programming on various Microchip PIC micro-controllers, and I found that the default asm-mode.el script did not handle the idiosyncrasies of the PIC assembly language very well. Therefore, I created pic-asm-mode.el as an extension to asm-mode.el. It syntax highlights PIC assembly mnemonics and handles formatting correctly.

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Dec 1, 2005

Perl Best Practices - POD Revisited

Damian Conway gave a tutorial in 2004 titled “Best Practices Perl” that describes a series of best practices concerning programming Perl applications. (Mike Kruckenberg wrote up a review of the presentation.) I agree with most of his points, but I do have a bit of a problem with the section of POD documenting. Damian mentions that: “put POD after END since the parser doesn’t have to parse the POD.”

I can agree with Damian’s point about not needing to parse the lines, but normally you would have comments there anyway. I believe it’s better to have the documentation in POD format rather than as comments. There is no appreciable difference in parsing speed between parsing POD and parsing comments.

Damian’s point that POD documentation at the end does not need to follow the layout of the code does have merit, but I believe it is outweighed by the need to keep code and documentation in sync. With the documentation as close as possible to the actual code it is easier to keep them aligned.

Finally, if performance is most important then all POD and all comments should be stripped from the files before placing in production. This would eliminate all parsing time. I would argue that this may be a good trade-off in specific instances, but not in general.

All told, I would recommend any Perl programmer picking up a copy of Damian’s book Perl Best Practices and incorporate those ideas they feel comfortable with. Highly recommended.

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Nov 30, 2005

Combo Button Lock Quiz Problem

Introduction

Matthias Wandel of Research in Motion (RIM) has a programming challenge posted on his website. The challenge is to write a program that generates all the possible combinations for an N button combination lock. The twist is the multi-button possibilities as well. Read on to see how I solved the problem.

Updated on November 29, 2005: The version described below is the second published version of the code. The first program was 160 lines of code and involved a more complicated way of producing the combinations. It is, however, faster than the current version.

Constraints

Matthias presents the programming challenge while describing the position of an embedded developer. The original code traded memory usage for more complicated code. The new version reverses this decision since the amount of memory consumed is still much lower than a typical 8-bit micro-controller. The other driving constraint is to keep the source to less than 100 lines of code. The current version is at 125, so there is still some room for improvement.

Theory of Operation

The problem can be described as a simple combinatoric (k-of-n) where an increasing number of keys are drawn (starting with one and increasing to a maximum of eight.) After each choice the permutations of the set are generated. Pretty straight forward.

The insight I had for the second version of the program is to pre-compute all the button pair combinations. With only eight possible keys, there are only:


total_pairs = (total_keys * (total_keys - 1)) / 2
            = (8 * (8 - 1)) / 2
            = 28

Therefore, there are 28 pair combinations plus eight single key presses for a total of 36 possible button presses. Now, I can consider the whole single versus pair problem as a simple k-of-36 with k increasing from 1 to 8. This simplifies a lot of the code.

Pairs are stored in a single integer as the upper and lower nibbles of a byte. Single buttons are also stored in an integer, but the upper nibble is zero to differentiate them from the pairs. The display routine uses this information to determine how the output should be handled.

In order to ensure that invalid combinations are not picked a simple bitmask is used to track the keys already used in the current combination. This decision does slow down the program a bit (with my tests showing the current code calculates all the combinations and permutations for eight keys in 4.6 seconds, while the older code could do the same in 2.9 seconds.)

I’m not happy about the slowdown in the execution, but the code is easier to understand, and the change did eliminate 35 lines of source code.

Source Code

The complete source code for combos.c can be compiled into an executable by doing: cc -o combos combos.c

Conclusion

I found the process of writing this application to be fascinating. I had never developed code requiring either permutations or combinations. Even after I wrote a version that solved the problem I still felt compelled to come up with a better version. At 125 lines, this version is closer to meeting the requirements of the challenge, but it’s still not enough. I’ll have to come back to this problem again.

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Nov 16, 2005

Still Looking for Work

After selling my business at the beginning of June, and getting married at the end of June, I am now looking for full-time work in the Simcoe and surrounding area. During the past few months I’ve done some consulting work for various companies, but unless a bunch of large consulting jobs materialize, I would much rather work for a stable company looking for a highly skilled IT professional.

My job search in the Simcoe area has been a bit frustrating, but I am hopeful that something will come along soon. I love Simcoe, and I would hate to have to leave simply because I could not get work in my chosen field. Far too many young people have left this community because of lack of opportunity. I don’t want to be the latest casualty.

So, if any of you know of any company in the Simcoe (or surrounding area) who could use my skills please let me know. Thank you.

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Oct 14, 2005

Eight Traits of a Creative Person

The following traits were listed in “Pencil Dancing” by Mari Messer as an example of what creative people posses. The author goes on to state that the reader should copy the list and then hilight the traits the reader currently possesses in one colour, and the traits they wish to further develop in another colour. The traits are posted where they can be daily seen, and a log is kept of the progress. From time to time the chart should be updated to reflect your current creative profile.

Courage

  • You’re not afraid to fail.
  • You think independently; you’re not overly influenced by others’ opinions.
  • You have confidence in your own abilities and insights.

Tenacity

  • You possess unwaning energy and enthusiasm.
  • You persevere despite difficulties.
  • You finish what you start.

Sensitivity

  • You’re open and receptive to new ways and ideas.
  • You’ve sensitive to a need or opportunity.
  • You have a keen awareness of your surroundings and of other people.

Flexibility

  • You’re not locked into doing things a certain way.
  • You’re quick to compromise and willing to try a new approach.
  • You’re eager to broaden experience by listening to other people’s ideas.

Originality

  • You have the ability to generate many unique answers to a single question, problem or situation.
  • Your creativity is a true expression of your real self.
  • You don’t strive to be original, but you naturally are.

Good Judgement

  • You can recognize a good idea or a bad one.
  • You show realistic insight.
  • You’re willing to test ideas in the real world.

Broad Experience and Skills

  • You show competence in a least one chosen field.
  • You have many interests.
  • You’re an articulate and persuasive communicator.

Playfulness

  • Your sense of humour is infectious and not harmful to others.
  • You honour the spirit of exploration and curiosity.
  • You’re not ashamed of your ability to fantasize, dream and imagine.
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