Re: Save a class into xml file?
- From: nallen05@xxxxxxxxx
- Date: 30 Dec 2006 00:45:50 -0800
eli.cox@xxxxxxxxx wrote:
Hello,
I have a program with several structures of data with variables (ready,
arrays,...) and I would like to write in a file xml. I would like to
know if I cand do this job easy, without having to write much code. I
am new in common lisp, recently I saw a video where xml directly loaded
the classes froma a file, maybe in a video of allego cache. Somebody
can give some link where I can obtains more information?
BKNR http://common-lisp.net/project/bknr/html/home.html has an XML
import/export package, which offers XML bindings for CLOS objects...
The video your thinking of might have been
http://franz.com/products/allegrocache/acachedemo.htm ? They generate
CLOS class definitions from an XML file... Do they actually serialize
the db? I don't remember, it's kind of long...
;Here's a quick hack
(defmacro wrap-in-tag ((stream tag-name &rest attribute-plist) &body
body)
(let ((s (gensym))
(n (gensym)))
`(let ((,s ,stream)
(,n ,tag-name))
(format ,s "<~A~{ ~A=\"~A\"~}>" ,n (list ,@attribute-plist))
(progn ,@body)
(format ,s "</~A>" ,n)
nil)))
;(wrap-in-tag (stream "tag" "attr" "val")
; (format t "text"))
;
; expands to:
;
;(LET ((#:G11006 STREAM) (#:G11007 "tag"))
; (FORMAT #:G11006 "<~A~{ ~A=\"~A\"~}>" #:G11007 (LIST "attr" "val"))
; (PROGN (FORMAT STREAM "text"))
; (FORMAT #:G11006 "</~A>" #:G11007) NIL)
;
; prints to STREAM:
;
;"<tag attr=\"val\">text</tag>"
;
; returns:
;
;NIL
(defgeneric render-slots (instance &optional stream)
(:method-combination progn))
(defmacro make-render-method (class-name slot-names)
`(defmethod render-slots progn ((x ,class-name) &optional (stream t))
(dolist (s ',slot-names)
(format stream "~% ")
(wrap-in-tag (stream "slot" "name" (string s))
(prin1 (slot-value x s) stream)))))
(defun render (instance &optional (stream t))
(wrap-in-tag (stream "instance" "class" (string (type-of instance)))
(render-slots instance stream)
(terpri stream)))
;now in use:
(defclass foo ()
((foo-slot :initarg :foo-slot)))
(defclass bar (foo)
((bar-slot :initarg :bar-slot)))
(defclass baz (bar)
((baz-slot :initarg :baz-slot)))
(make-render-method foo (foo-slot))
(make-render-method bar (bar-slot))
(make-render-method baz (baz-slot))
(setf x (make-instance 'baz
:foo-slot 1
:bar-slot 2
:baz-slot 3))
(render x)
#|
prints:
<instance class="BAZ">
<slot name="BAZ-SLOT">3</slot>
<slot name="BAR-SLOT">2</slot>
<slot name="FOO-SLOT">1</slot>
</instance>
of course none of the resultant text is gauranteed to be XML safe... or
printed in such a way... also remember about symbol packages and how
they read...
still, though, as you can see, this wouldn't be that big of a deal to
do it right...
if you are using an implementation with MOP you could use the CLASS-
functions
http://www.franz.com/support/documentation/8.0/doc/mop/dictionary.html#class-
to make a RENDER fn that fishes out all the class info of an instance
by itself so you don't have to do a MAKE-RENDER-METHOD by hand for
every class...
hth, take care
Nick
|#
Bye
Elizabeth.
.
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