wise memo.txt

Ethan Bolker
May, 2004

Continuing where I left off ...

Decided to use a command dispatch table, but not to import the full
strength of Juno - no Shell, no ShellCommandTable. Just put that
functionality into WISE. We'll see if I come to regret that decision.

Realized that the schedule for each Student can just be an instance of
a WISEList, allowing me to reuse the getPrintableList code already in
place. All I have to do is create a new header. Did that with an inner
class in Student. Once that's working I will use the same strategy for
the Professor schedule and the Course list of students.

Changed student ID field from String to int, to make id lookup easier
some day. Ended up changing it back again - found a better lookup
strategy.

OK - assign, enroll and type are done, with most of the error checking -
except for TimeOfDay conflicts! Haven't touched those yet.

There's some refactoring still to be done - repeated code that can be
moved to a single place.

file command and type command need to share lots of code, so I have
created an abstract OutputCommand as parent to both.

Now to tackle times. Created a static array of legal times in
TimeOfDay class. Each professor, student, course has an
isAvailable(TimeOfDay) method, with semantics obvious for professor
and student. For course, isAvailable() returns tru just when the
TimeOfDay argument is the time at which the course is offered and the
course has room in it.

The different semantics for isAvailable and other things I have
encountered tell me that I really should have a WISEPerson class
extending WISEObject with Student and Professor as subclasses, since
they share functionality that Course objects don't. But it's too late
in the development cycle to make that change.

Collected all my tests into a set of executable files *.sh. These are
Unix shell scripts, so they won't work on windows, but it's easy
enough to pull out the WISE commands and use i/o redirection. 

My implementation uses 18 classes; the source is about 1200 lines of
Java. It uses 28 "if" expressions and no "else". Most of those if's
are for error detection - polymorphism handles the logical branching.

AssignCommand
AvailableCommand
Course
CourseList
EnrollCommand
FileCommand
OutputCommand	
Professor	
ProfessorList	
Student		
StudentList		
TimeOfDay
TypeCommand
WISE
WISECommand
WISEException
WISEList
WISEObject