common-lisp CLOS - the Common Lisp Object System Creating a basic CLOS class without parents
Example
A CLOS class is described by:
- a name
- a list of superclasses
- a list of slots
- further options like documentation
Each slot has:
- a name
- an initialization form (optional)
- an initialization argument (optional)
- a type (optional)
- a documentation string (optional)
- accessor, reader and/or writer functions (optional)
- further options like allocation
Example:
(defclass person ()
((name
:initform "Erika Mustermann"
:initarg :name
:type string
:documentation "the name of a person"
:accessor person-name)
(age
:initform 25
:initarg :age
:type number
:documentation "the age of a person"
:accessor person-age))
(:documentation "a CLOS class for persons with name and age"))
A default print method:
(defmethod print-object ((p person) stream)
"The default print-object method for a person"
(print-unreadable-object (p stream :type t :identity t)
(with-slots (name age) p
(format stream "Name: ~a, age: ~a" name age))))
Creating instances:
CL-USER > (make-instance 'person)
#<PERSON Name: Erika Mustermann, age: 25 4020169AB3>
CL-USER > (make-instance 'person :name "Max Mustermann" :age 24)
#<PERSON Name: Max Mustermann, age: 24 4020169FEB>
