Common Lisp

1
Common Lisp!

• John Paxton
• Montana State University
• Summer 2003

2
Bozeman Facts

• John Bozeman came west in search of gold.
• For a while, he guided settlers west in covered
  wagon trains.
• In 1863, he entered the Gallatin Valley for the
  first time and established Bozeman.

3
CLOS

• Common Lisp Object System
• Objects
• Methods
• Inheritance

4
Class Declaration

• (defclass city ()
• (
• (name accessor name)
• (country accessor country)
• (population accessor population)
• )
• )

5
Class Instantiation

• gt (setf bozeman (make-instance 'city))
• ltCITY x20383741gt

6
Accessing Data Fields

• gt (setf (name bozeman) 'bozeman)
• BOZEMAN
• gt (setf (country bozeman) 'usa)
• USA
• gt (setf (population bozeman) 30000)
• 30000

7
Writing Methods

• (defmethod my-print ((some-city city))
• (format t "The city's name is a"
• (name some-city))
• (format t "The city's country is a
• (country some-city))
• )

8
Calling Methods

• gt (my-print bozeman)
• The city's name is BOZEMAN
• The city's country is USA

9
Using Inheritance

• (defclass montana-city (city)
• (
• (culture-level accessor culture-level)
• )
• )

10
Using Inheritance

• gt (setf two-dot (make-instance
• 'montana-city))
• ltMONTANA-CITY x203BDA7Dgt
• gt (setf (name two-dot) 'two-dot)
• gt (setf (country two-dot) usa)
• gt (setf (population two-dot) 172)
• gt (setf (culture-level two-dot) 'low)

11
Using Inheritance

• gt (my-print two-dot)
• The city's name is TWO-DOT
• The city's country is USA

12
Using Inheritance

• (defmethod my-print
• ((some-city montana-city))
• (format t "The city's name is a"
• (name some-city))
• (format t "The city's culture-level is a
• (culture-level some-city))
• )

13
Using Inheritance

• gt (my-print two-dot)
• The city's name is TWO-DOT
• The city's culture-level is LOW

14
Questions

• Use CLOS to define a class named generic-list.
  This class should have methods called make-empty,
  is-empty, insert-item and remove-item.
  Insert-item and remove-item should both operate
  from the front of the list. Demonstrate that the
  class works.

15
Questions

• Define a class called stack. Inherit as many
  methods as possible.
• Define a class called queue. Inherit as many
  methods as possible.