Held: ,

Back to Outline 14 - Codes of Ethics. On to Outline 16 - Legacy Code.

Summary

We consider issues in writing correct code, particularly test-driven development and ways to identify code that is likely to have errors.

Related Pages

Overview

• Review: Buggy code.
• Loop invariants.
• Surveillance.

Administrivia

Upcoming Work

• Readings for Friday: SaaS 9, 10.4-10.8.
• Reading Journal for Friday (due Thursday at 8pm) [As is often the case, these questions were inspired by the work of JLND.]
  • Subject: Reading Journal for Class 16 (Your Name)
  • How does the description of Software Mainenance reflect your own expectations or experiences about such issues? What was familiar? What was surprising?
  • What is the most important thing you learned from Chapter 9, Software Maintenance (textbook or videos)?
  • What was the muddiest point from this material? Explain that idea in your own words as best you can.

Good Things to Do

See http://www.cs.grinnell.edu/~rebelsky/s2d@g/

• Jiu Jitsu tonight at 6:30 p.m.
• Convocation tomorrow.
• CS Pin-i-nic Friday.

Refresher: Incorrect code

What does this program try to do?

class TimeSetter
  def self.convert(d)
    y = 1980
    while (d > 365) do
      if ((y % 400 == 0) || (y % 4 == 0) && (y % 100 != 0))
        if (d > 366)
          d -= 366
          y += 1
        end
      else
        d -= 365
        y += 1
      end
    end
    return [y,d]
  end
end

What is wrong with this program?

How would we find it?

How would we fix it?

Loop invariants

• The CSC207 part of my brain wants you to fix this with loop invariants.
• So let's remember what loop invariants are. Three main aspects.
• How would the help with this program?

Global Surveillance

"I would like to discuss the idea of global surveillance and where to draw the line. It's a grey area for me and I'd like to get more opinions on it."

• Arguing for as much surveillance as possible: MG, CG, NT, AH, SH, YL, EZ, GN
• Arguing for a moderate position: ST, RW, BR
• Arguing for none whatsoever: Everyone else.