1. Meta-objective
Lisp
@dico_leque
2011/02/26 NagoyaRejectKaigi

2. n Common Lisp Object System Metaobject
Protocol
n Gauche Scheme interpreter

3. Lisp
n CLOS -- Common Lisp Object System
n
n ISLISP Object System -- ILOS
n Ruby
n ANSI Common Lisp Lisp

4. CLOS (1)
n
n (define-class <foo> () ((slot1) (slot2)))
n
n (define-class <baz> (<foo> <bar>) ())

5. CLOS (2)
n generic-
function
n
(define-generic foo)
(define-method foo ((x <sequence>) (y <sequence>)) 0)
(define-method foo ((x <sequence>) (y <string>)) 1)
(define-method foo ((x <string>) (y <sequence>)) 2)
(define-method foo ((x <string>) (y <string>)) 3)
(foo '() '()) ; => 0
(foo '() "a") ; => 1
(foo "a" '#()) ; => 2
(foo "a" "b") ; => 3

6. CLOS (3)
n CLOS CLOS
n
n

7. MOP
n Metaobject Protocol
n introspection:
API
n intercessory:
API
n intercessory

8. Metaobjects
n
n <class> <generic> <method>
n
(make <class>) (apply-generic-function <generic>)

9. (1)
n
n <singleton-meta>
make
n (instance-of < >)
n singleton singleton

10. (1)
(define-class <singleton-meta> (<class>)
(%the-singleton-instance)
)
(define-method make ((class <singleton-meta>) . initargs)
...)
(define-method instance-of ((class <singleton-meta>) . initargs)
(apply make class initargs))
(define-class <singleton-mixin> ()
()
:metaclass <singleton-meta>)
from gauche/lib/gauche/mop/singleton.scm

11. (2) O/R
n DB
n <orm> DB

12. (2) O/R
(define-class <orm> (<class>) ())
(define-method compute-slots ((cl <orm>))
(let ((super-slots (next-method)))
(lset-union
(lambda (x y)
(eq? (car x) (car y)))
(map (lambda (name)
`(,name
:init-keyword ,(make-keyword name)
:accessor ,(string->symbol (format "~A-of" name))))
(load-slot-names cl))
super-slots)))
(define-class <foo> () ()
:metaclass <orm>)
※ load-slot-names

13. (3)
n Ruby
n
n (eql 0) 0
n <generic> (eql x)

14. (3)
(define-generic fact
:class <eql-specializable-generic>)
(define-method fact ((n (eql 0)))
1)
(define-method fact ((n <integer>))
(* n (fact (- n 1))))

15. (3)
(define-class <eql-specializer> (<class>)
((object
:getter eql-specializer-object
:init-keyword :eql-specializer-object)))
(define (eql obj)
(make <eql-specializer> :eql-specializer-object obj))
(define-class <eql-specializable-generic> (<generic>) ())
(define-method compute-applicable-methods
((gf <eql-specializable-generic>) args)
...)
(define-method sort-applicable-methods
((gf <eql-specializable-generic>) methods args)
...)
※ 60 http://d.hatena.ne.jp/leque/20110105/p1

16. CLOS / MOP
n
n DB
n
n validator

17. CLOS / MOP
n
n
Pascal Costanza, Charlotte Herzeel, Jorge Vallejos, Theo D’Hondt:
“Filtered dispatch”, Proceedings of the 2008 symposium on Dynamic
languages
n
n before, after, around
n

18. CLOS / MOP
n
n
n lazy initialization
n

19. DSL MOP
n DSL Domain
n

20. n Lisper
DSL
n CLOS MOP