TITLE: Memories of a Programming Assignment
AUTHOR: Eugene Wallingford
DATE: November 16, 2011  2:38 PM
DESC: 
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BODY:
Last Friday afternoon, the CS faculty met with the
department's advisory board.  The most recent addition to
the board is an alumnus who graduated a decade ago or so.
At one point in the meeting, he said that a particular
programming project from his undergraduate days stands
out in his mind after all these years.  It was a series
of assignments from my Object-Oriented Programming course
called Cat and Mouse.

I can't take credit for the basic assignment.  I got the
idea from
<A HREF="http://www.eecs.berkeley.edu/~clancy/">
   Mike Clancy</A>
in the mid 1990s.  (He later presented
<A HREF="http://nifty.stanford.edu/catandmouse/html/">
   his version of the assignment</A>
on the original
<A HREF="http://nifty.stanford.edu/">
   Nifty Assignments</A>
panel at SIGCSE 1999.)  The problem includes so many cool
features, from coordinate systems to stopping conditions.
Whatever one's programming style or language, it is a
fun challenge.  When done OO in Java, with great support
for graphics, it is even more fun.

But those properties aren't what he remembers best about
the project.  He recalls that the project took place over
several weeks and that each week, I changed the requirements
of assignment.  Sometimes, I added a new feature.  Other
times, I generalized an existing feature.

What stands out in his mind after all these years is
getting the new assignment each week, going home,
reading it, and thinking,

<BLOCKQUOTE><EM>
@#$%#^.  I have to rewrite my entire program.
</EM></BLOCKQUOTE>

You, see he had hard-coded assumptions throughout his
code.  Concerns were commingled, not separated.  Objects
were buried inside larger pieces of code.  Model was
tangled up with view.

So, he started from scratch.  Over the course of several
weeks, he built an <EM>object-oriented</EM> system.  He
came to understand dynamic polymorphism and patterns
such as MVC and decorator, and found ways to use them
effectively in his code.

He remembers the dread, but also that this experience
helped him learn how to write software.

I never know exactly what part of what I'm doing in class
will stick most with students.  From semester to semester
and student to student, it probably varies quite a bit.
But the experience of growing a piece of software over
time in the face of growing and changing requirements is
almost always a powerful teacher.
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