We will use codewalks, a common practice at software companies, to evaluate some of your programs. A codewalk is a presentation where you, the programmer, convince us, a jury, of specific properties of your program. You accomplish this by presenting your program and answering questions about it. We are most interested in

  • correctness: does it do the right thing?,
  • extensibility: how adaptable is it to related tasks?,
  • robustness: is it built like a house of cards?, and
  • performance: does it avoid poor implementation decisions?.

We will conduct two or three codewalks during the semester. Codewalks will evaluate the programs turned in as solutions to regular homework assignments. Each program will receive about 30 minutes of scrutiny. The code you present must the be the same code you turned in as your homework solution. Here's the catch: You don't find out whether we will conduct a codewalk on an assignment until after you turn in your solution for it. No excuses or exceptions; you read it here.

We conduct codewalks for two reasons, one pedagogic and one technical. The technical reason is that the assignments in this course offer a microcosmic example of typical software evolution, so this is an opportunity for you to hone your software construction skills. The pedagogic reason is that codewalks offer students the richest and most immediate critiques of their programs, while giving instructors a very effective way of judging student understanding.

The real-time nature of codewalks tends to favor simplicity and cleanliness over both sloppiness and (excessive) cleverness. In this course, it's extremely unlikely that advanced language features will offer either desirable property. Keep things simple and you are least likely to run afoul of questions.


A codewalk is primarily a presentation, by you to us, so all the usual formalities of presentations apply (except, of course, please don't dress formally for the occasion!). It is not a chat or discussion session. Treat it as you would a formal presentation in any other course. The only difference is the content of your slides.

Your presentation must cover the programs that you wrote for the assigned homework. Follow these simple rules:

  • Print out the program. Transfer it to overhead transparencies. Conduct your presentation using an overhead projector (which we'll provide).
  • Before you print, put some effort into making sure the presentation is reasonable. Break excessively long and unruly lines to a more manageable length. Don't split a function body across page break boundaries. Use common sense. We really are going to read your code. If the physical presentation is unreadable, it's going to be harder to convince us of its behavior. (But don't spend time fontifying it and so forth. Plain Courier is fine. So is using SLaTeX.)
  • Other than formatting changes, you may not alter your program. In particular, you may not change its behavior in any way.
  • Bring along, preferably also on slides, auxilliary parts of your homework such as test-cases (if applicable).
  • If an assignment involves software we can test easily, such as a CGI program, please set it up to be accessible from the Brown computer science department, and bring instructions on how to run it. If we cannot run your program, we will consider it incorrect.

You should present the complete content of your program. Be flexible in your presentation. We may ask you to skip the details of some part, elaborate on the details of some other part, or even re-order your presentation entirely. Remind yourself of the goal of a code-walk.

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