EXERCISE 12.1
Recall the CCT description of the rule
INSERT-SPACE-2 discussed in Section 12.2.2:
(INSERT-SPACE-2
IF (AND (TEST-GOAL insert space)
(TEST-CURSOR %LINE %COL) )
THEN ( (DO-KEYSTROKE 'I')
(DO-KEYSTROKE SPACE)
(DO-KEYSTROKE ESC)
(DELETE-GOAL insert space) ))
As we discussed, this is already proceduralized,
that is the rule is an expert rule. Write new 'novice'
rules where the three keystrokes are not proceduralized.
That is, you should have separate rules for each keystroke
and suitable goals (such as GET-INTO-INSERT-MODE)
to fire them.
answer
(INSERT-SPACE-BEGIN-SET-MODE
IF (AND (TEST-GOAL insert space)
(TEST-CURSOR %LINE %COL)
(TEST-NOTE in command mode ))
THEN ( (ADD-GOAL get into insert mode)))
(INSERT-SPACE-END-SET-MODE
IF (AND (TEST-GOAL insert space)
(TEST-GOAL get into insert mode))
THEN ( (DO-KEYSTROKE `I')
(ADD-NOTE in insert mode)
(DELETE-GOAL get into insert mode)))
(INSERT-SPACE-DOIT
IF (AND (TEST-GOAL insert space)
(TEST-NOTE in insert mode)
(TEST-CURSOR %LINE %COL))
THEN ( (DO-KEYSTROKE SPACE)
(ADD-GOAL get into command mode)))
(INSERT-SPACE-CLEAN-UP
IF (AND (TEST-GOAL insert space)
(TEST-NOTE in insert mode)
(TEST-GOAL get into command mode))
THEN ( (DO-KEYSTROKE ESC)
(DELETE-GOAL get into command mode)
(DELETE-GOAL insert space)
(DELETE-NOTE in insert mode)
(ADD-NOTE in command mode)))
EXERCISE 12.2
One of the assumptions underlying the
programmable user model approach is that it is possible
to provide an algorithm to describe the user's behaviour
in interacting with a system. Taking this position
to the extreme, choose some common task with a familiar
interactive system (for example, creating a column
of numbers in a spreadsheet and calculating their
sum, or any other task you can think of) and describe
the algorithm needed by the user to accomplish this
task. Write the description in pseudocode. Does this
exercise suggest any improvements in the system?
