Is there symbol-plist functionality in Emacs Lisp?

Is there symbol-plist functionality in Emacs Lisp?

[Jean Louis]

The function `symbol-plist' in Emacs Lisp returns only properties:

> (symbol-plist SYMBOL)
>   This function does not change global state, including the match data.

While `symbol-plist' in Common Lisp returns the definition as below.

Is there equivalent Emacs Lisp function that could return me the full
definition of a function?

(symbol-plist 'save-function)

(SYSTEM::DEFINITION
 ((DEFUN SAVE-FUNCTION (F)
   "Saves the function in the file *my-function-dir*/function-name.lisp. 
Invoke it as: (SAVE-FUNCTION 'FUNCTION-NAME) or (SAVE-FUNCTION \"FUNCTION-NAME\")"
   (LET
    ((FUNCTION-NAME (CAR (CADR (SYMBOL-PLIST (INTERN (STRING-UPCASE F))))))
     (FUNCTION-FILE
      (FORMAT NIL "~a/~a.lisp" *MY-FUNCTION-DIR*
       (STRING-DOWNCASE
        (SUBSTITUTE #\- #\? (IF (SYMBOLP F) (SYMBOL-NAME F) (SYMBOL-NAME (INTERN (STRING-UPCASE F)))))))))
    (WITH-OPEN-FILE (STR FUNCTION-FILE :DIRECTION :OUTPUT :IF-DOES-NOT-EXIST :CREATE)
     (PRINT FUNCTION-NAME STR))))
  .
  #(NIL NIL NIL NIL
    ((DECLARATION OPTIMIZE DECLARATION DYNAMICALLY-MODIFIABLE SYSTEM::IMPLEMENTATION-DEPENDENT))))
 SYSTEM::DOC (SYSTEM::FILE ((SYSTEM::DEFUN/DEFMACRO #P"/home/data1/protected/bin/rcd/save-lisp.lisp" 8 8))))



Jean

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Re: Is there symbol-plist functionality in Emacs Lisp?

[Stefan Monnier via Users list for the GNU Emacs text editor]

> While `symbol-plist' in Common Lisp returns the definition as below.

Is that really true of Common Lisp, or just of some implementations?
I can't seem to find that documented in the CLHS.


        Stefan

FW: [External] : Re: Is there symbol-plist functionality in Emacs Lisp?

[Drew Adams]

[Forwarding to the list.  Bitten again by "Reply All"
not including the list, for some reason.]

> > While `symbol-plist' in Common Lisp returns the definition as below.
> 
> Is that really true of Common Lisp, or just of some implementations?
> I can't seem to find that documented in the CLHS.

What Stefan said.  AFAIK, the specs (CLTL2, CLHS)
say nothing about what is or might be in the plist.

I think the answer to the question of why Elisp
`symbol-plist' doesn't return the function def
in the plist is because in Elisp the function
def isn't in the plist.

As for how to get the function def, the answer
is `symbol-function', AFAIK.

Re: Is there symbol-plist functionality in Emacs Lisp?

[Jean Louis]

* Stefan Monnier via Users list for the GNU Emacs text editor <help-gnu-emacs@gnu.org> [2021-05-08 17:01]:
> > While `symbol-plist' in Common Lisp returns the definition as below.
> 
> Is that really true of Common Lisp, or just of some implementations?
> I can't seem to find that documented in the CLHS.

True, it works just in CLISP. Is there equivalent in Emacs that I can
get a function definition this way?

[1]> (defun myfn (a) a)
MYFN

[2]> (SYMBOL-PLIST (INTERN (STRING-upcase "myfn")))
(SYSTEM::DEFINITION
 ((DEFUN MYFN (A) A) .
  #(NIL NIL NIL NIL
    ((DECLARATION OPTIMIZE DECLARATION DYNAMICALLY-MODIFIABLE SYSTEM::IMPLEMENTATION-DEPENDENT)))))


-- 
Jean

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Re: Is there symbol-plist functionality in Emacs Lisp?

[Stefan Monnier]

>> > While `symbol-plist' in Common Lisp returns the definition as below.
>> Is that really true of Common Lisp, or just of some implementations?
>> I can't seem to find that documented in the CLHS.
> True, it works just in CLISP. Is there equivalent in Emacs that I can
> get a function definition this way?

Depends what you mean by "function definition", IOW depends what you
want to do with it.  There `symbol-function` of course, and there are
also things like `find-function-noselect`.


        Stefan

Re: FW: [External] : Re: Is there symbol-plist functionality in Emacs Lisp?

[Jean Louis]

* Drew Adams <drew.adams@oracle.com> [2021-05-08 17:39]:
> As for how to get the function def, the answer
> is `symbol-function', AFAIK.

That is it.

(symbol-function 'rcd-markdown) ⇒ (closure (t) (text) "Markdown processing" (if text (rcd-command-output-from-input "markdown" text) ""))

I see what it means in the manual:

,----
|    Currently, an Emacs Lisp closure object is represented by a list with
| the symbol ‘closure’ as the first element, a list representing the
| lexical environment as the second element, and the argument list and
| body forms as the remaining elements:
| 
|      ;; lexical binding is enabled.
|      (lambda (x) (* x x))
|           ⇒ (closure (t) (x) (* x x))
`----

If not defined under lexical scoping it looks like:

(symbol-function 'myfn) ⇒ (lambda (a) a)

Thank you, yhat is good enough, as it is list and I can, under
conditions, change it to become able to save the function. It
serves tracking of some unused and soon to be deleted functions.

(defun save-function (f)
  (let* ((fun (symbol-function f))
	 (type (car fun)))
    (cond ((eq type 'lambda) (setq fun (append (list 'defun f) (cdr fun))))
	  ((eq type 'closure) (setq fun (append (list 'defun f) (nthcdr 2 fun)))))
    ;; save to file comes here
    fun))

(defun myfn (a) (+ 2 2 a))

(save-function 'myfn) ⇒ (defun myfn (a) (+ 2 2 a))

(save-function 'rcd-markdown) ⇒ (defun rcd-markdown (text) "Markdown processing" (if text (rcd-command-output-from-input "markdown" text) ""))

(defun string-to-file-force (string file)
  "Prints string into file, matters not if file exists. Returns FILE as file name."
    (with-temp-file file
      (insert string))
    file)

Then now I can save at least those functions defined by myself, it
serves my long term introspection, and preservation of single, from
file deleted functions.

(defun save-function ()
  (interactive)
  (let ((function (function-called-at-point)))
    (when (and (symbolp function)
	       (y-or-n-p (format "Save `%s'" (symbol-name function))))
      (let* ((fun (symbol-function function))
	     (type (car fun))
	     (file (concat "/tmp/function-" (symbol-name function) ".el")))
    (cond ((eq type 'lambda) (setq fun (append (list 'defun function) (cdr fun))))
	  ((eq type 'closure) (setq fun (append (list 'defun function) (nthcdr 2 fun)))))
    (message (string-to-file-force (prin1-to-string fun) file))))))

(define-key emacs-lisp-mode-map (kbd "<f6>") 'save-function)

It gives output like this, that is acceptable:

(defun save-function nil (interactive) (let (#'(function-called-at-point)) (if (and (symbolp function) (y-or-n-p (format "Save `%s'" (symbol-name function)))) (progn (let* ((fun (symbol-function function)) (type (car fun)) (file (concat "/tmp/function-" (symbol-name function) ".el"))) (cond ((eq type 'lambda) (setq fun (append (list 'defun function) (cdr fun)))) ((eq type 'closure) (setq fun (append (list 'defun function) (nthcdr 2 fun))))) (message (string-to-file-force (prin1-to-string fun) file)))))))



-- 
Jean

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Re: Is there symbol-plist functionality in Emacs Lisp?

[Jean Louis]

* Stefan Monnier <monnier@iro.umontreal.ca> [2021-05-08 18:48]:
> >> > While `symbol-plist' in Common Lisp returns the definition as below.
> >> Is that really true of Common Lisp, or just of some implementations?
> >> I can't seem to find that documented in the CLHS.
> > True, it works just in CLISP. Is there equivalent in Emacs that I can
> > get a function definition this way?
> 
> Depends what you mean by "function definition", IOW depends what you
> want to do with it.  There `symbol-function` of course, and there are
> also things like `find-function-noselect`.

Thank you.

When I was working in Common Lisp REPL, I have used CLISP, and it was
handy to save a function that is deleted from file.

(defun save-function ()
  "Saves function at point"
  (interactive)
  (let ((function (function-called-at-point)))
    (when (and (symbolp function)
	       (y-or-n-p (format "Save `%s'" (symbol-name function))))
      (let* ((fun (symbol-function function))
	     (type (car fun))
	     (file (concat "/tmp/function-" (symbol-name function) ".el")))
    (cond ((eq type 'lambda) (setq fun (append (list 'defun function) (cdr fun))))
	  ((eq type 'closure) (setq fun (append (list 'defun function) (nthcdr 2 fun)))))
    (message (string-to-file-force (prin1-to-string fun) file))))))

(defun save-function-delete ()
  (save-function)
  (beginning-of-line)
  (mark-sexp)
  (delete-active-region))

Now if I wish to delete a function, but save it before hand, I would
go to "save-function-delete" and invoke the key to run
`safe-function-delete'

It would save itself from memory, not from file as for future possible
introspection and delete it from the file in the same time.

-- 
Jean

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Re: FW: [External] : Re: Is there symbol-plist functionality in Emacs Lisp?

[Emanuel Berg via Users list for the GNU Emacs text editor]

Drew Adams wrote:

> AFAIK, the specs (CLTL2, CLHS) say nothing about what is or
> might be in the plist.

CLTL2 = Common Lisp the Language, 2nd Edition,
https://www.cs.cmu.edu/Groups/AI/html/cltl/cltl2.html

CLHS = Common Lisp HyperSpec,
http://www.lispworks.com/documentation/lw50/CLHS/Front/Contents.htm

"HyperSpec" BTW :)

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