Do me a favor, would you? Have a quick look at this code and tell me what you think it does...
MysteryProcedureUsingCodeBlock (long StudentID)!,long ! Declare Procedure
FilesOpened BYTE(0)
Result long
StepNumber long
MostAvoidedTeacher cstring(100)
CourseTakenQ Queue
CourseID long
TeacherID long
end
CourseNotTakenQ Queue
CourseID long
TeacherID long
end
CourseQ Queue
CourseID long
Taken BOOL
end
TeacherQ Queue
TeacherID Long
ClassesTaught Long
end
x long
WasTaken bool
CODE
do OpenFiles
STU:StudentID = StudentID
get(Student,STU:pkStudentID)
if errorcode()
do CloseFiles
return FALSE
end
set(Course)
loop
next(Course)
if errorcode() then break.
clear(CRSI:Record)
CRSI:CourseID = CRS:CourseID
set(CRSI:kCourseIDTeacherID,CRSI:kCourseIDTeacherID)
WasTaken = false
loop
next(CourseInstance)
if errorcode() or CRSI:CourseID <> CRS:CourseID then break.
ENR:StudentID = StudentID
ENR:CourseInstanceID = crsi:CourseInstanceID
get(Enrollment,ENR:kCourseInstanceUDStudentID)
if not errorcode()
WasTaken = TRUE
break
end
end
if WasTaken
clear(CourseTakenQ)
CourseTakenQ.CourseID = CRS:CourseID
CourseTakenQ.TeacherID = CRSI:TeacherID
add(CourseTakenQ)
else
clear(CourseNotTakenQ)
CourseNotTakenQ.CourseID = CRS:CourseID
CourseNotTakenQ.TeacherID = CRSI:TeacherID
add(CourseNotTakenQ)
end
end
set(Teacher)
loop
next(Teacher)
if errorcode() then break.
TeacherQ.TeacherID = TEA:TeacherID
add(TeacherQ)
end
loop x = 1 to records(CourseTakenQ)
get(CourseTakenQ,x)
TeacherQ.TeacherID = CourseTakenQ.TeacherID
get(TeacherQ,TeacherQ.TeacherID)
if not errorcode() ! should always find a record
TeacherQ.ClassesTaught += 1
put(TeacherQ)
end
end
sort(TeacherQ,-TeacherQ.ClassesTaught)
loop while not errorcode()
get(TeacherQ,6)
delete(TeacherQ)
end
x = 1
loop
get(CourseNotTakenQ,x)
if errorcode() then break.
TeacherQ.TeacherID = CourseNotTakenQ.TeacherID
get(TeacherQ,TeacherQ.TeacherID)
if not errorcode()
x += 1
else
delete(CourseNotTakenQ)
end
end
TeacherQ.TeacherID = CourseNotTakenQ.TeacherID
get(TeacherQ,TeacherQ.TeacherID)
get(CourseNotTakenQ,random(1,records(CourseNotTakenQ)))
do CloseFiles
return false ! because this code is not yet complete
How are you making out? Do you have a clear idea of what this code does?
If you study the code long enough you should be able to figure out what it does, but you probably still won't know why it's doing what it does.
Now consider this version of the same code (I've omitted the OpenFiles/CloseFiles routines in both cases):
MysteryProcedureUsingLocalProcedures (long StudentID)!,long ! Declare Procedure
map
GetStudentRecord(),long
BuildListsOfCoursesTakenAndNotTaken(),long
CourseWasTaken(),long
BuildListOfTeachers(),long
CountCoursesTaughtToStudent(),long
SortTeacherListByCountOfCoursesTaughtToStudent(),long
NarrowTeacherListToFiveMostAvoided(),long
NarrowCourseNotTakenListToThoseTaughtByFiveMostAvoidedTeachers(),long
CourseIsTaughtByOneOfFiveMostAvoidedTeachers(),long
RegisterStudentForRandomlyChosenCourse(),long
end
FilesOpened BYTE(0)
Result long
StepNumber long
MostAvoidedTeacher cstring(100)
CourseTakenQ Queue
CourseID long
TeacherID long
end
CourseNotTakenQ Queue
CourseID long
TeacherID long
end
CourseQ Queue
CourseID long
Taken BOOL
end
TeacherQ Queue
TeacherID Long
ClassesTaught Long
end
CODE
do OpenFiles
StepNumber = 0
Result = Level:Benign
Loop while Result = Level:Benign
StepNumber += 1
execute StepNumber
Result = GetStudentRecord()
Result = BuildListsOfCoursesTakenAndNotTaken()
Result = BuildListOfTeachers()
Result = CountCoursesTaughtToStudent()
Result = SortTeacherListByCountOfCoursesTaughtToStudent()
Result = NarrowTeacherListToFiveMostAvoided()
Result = NarrowCourseNotTakenListToThoseTaughtByFiveMostAvoidedTeachers()
Result = RegisterStudentForRandomlyChosenCourse()
break
end
end
do CloseFiles
Return result
GetStudentRecord procedure()!,long
code
STU:StudentID = StudentID
get(Student,STU:pkStudentID)
if not errorcode() then return level:benign.
return level:notify
BuildListsOfCoursesTakenAndNotTaken procedure()!,long
code
set(Course)
loop
next(Course)
if errorcode() then break.
if CourseWasTaken() = Level:Benign
clear(CourseTakenQ)
CourseTakenQ.CourseID = CRS:CourseID
CourseTakenQ.TeacherID = CRSI:TeacherID
add(CourseTakenQ)
else
clear(CourseNotTakenQ)
CourseNotTakenQ.CourseID = CRS:CourseID
CourseNotTakenQ.TeacherID = CRSI:TeacherID
add(CourseNotTakenQ)
end
end
return Level:Benign
CourseWasTaken procedure()!,long
WasTaken bool
code
clear(CRSI:Record)
CRSI:CourseID = CRS:CourseID
set(CRSI:kCourseIDTeacherID,CRSI:kCourseIDTeacherID)
loop
next(CourseInstance)
if errorcode() or CRSI:CourseID <> CRS:CourseID then break.
ENR:StudentID = StudentID
ENR:CourseInstanceID = crsi:CourseInstanceID
get(Enrollment,ENR:kCourseInstanceUDStudentID)
if not errorcode()
WasTaken = TRUE
break
end
end
if WasTaken then return level:benign.
return level:notify
BuildListOfTeachers procedure()!,long
code
set(Teacher)
loop
next(Teacher)
if errorcode() then break.
TeacherQ.TeacherID = TEA:TeacherID
add(TeacherQ)
end
return Level:Benign
CountCoursesTaughtToStudent procedure()!,long
x long
code
loop x = 1 to records(CourseTakenQ)
get(CourseTakenQ,x)
TeacherQ.TeacherID = CourseTakenQ.TeacherID
get(TeacherQ,TeacherQ.TeacherID)
if not errorcode() ! should always find a record
TeacherQ.ClassesTaught += 1
put(TeacherQ)
end
end
return Level:Benign
SortTeacherListByCountOfCoursesTaughtToStudent procedure()!,long
code
sort(TeacherQ,-TeacherQ.ClassesTaught)
return Level:Benign
NarrowTeacherListToFiveMostAvoided procedure()!,long
x Long
code
loop while not errorcode()
get(TeacherQ,6)
delete(TeacherQ)
end
return Level:Benign
NarrowCourseNotTakenListToThoseTaughtByFiveMostAvoidedTeachers procedure()!,long
x long
code
x = 1
loop
get(CourseNotTakenQ,x)
if errorcode() then break.
if CourseIsTaughtByOneOfFiveMostAvoidedTeachers() = Level:Benign
x += 1
else
delete(CourseNotTakenQ)
end
end
return Level:Benign
CourseIsTaughtByOneOfFiveMostAvoidedTeachers procedure()!,long
code
TeacherQ.TeacherID = CourseNotTakenQ.TeacherID
get(TeacherQ,TeacherQ.TeacherID)
if not errorcode() then return Level:Benign.
return Level:Notify
RegisterStudentForRandomlyChosenCourse procedure()!,long
code
get(CourseNotTakenQ,random(1,records(CourseNotTakenQ)))
return Level:Notify ! because this code is not yet complete
do OpenFiles
StepNumber = 0
Result = Level:Benign
Loop while Result = Level:Benign
StepNumber += 1
execute StepNumber
Result = GetStudentRecord()
Result = BuildListsOfCoursesTakenAndNotTaken()
Result = BuildListOfTeachers()
Result = CountCoursesTaughtToStudent()
Result = SortTeacherListByCountOfCoursesTaughtToStudent()
Result = NarrowTeacherListToFiveMostAvoided()
Result = NarrowCourseNotTakenListToThoseTaughtByFiveMostAvoidedTeachers()
Result = RegisterStudentForRandomlyChosenCourse()
break
end
end
do CloseFiles
Return result