Re: [Fwd: Re: beginning-of-defun]

[Andreas Roehler]

Thien-Thi Nguyen schrieb:
> Andreas Roehler <address@hidden> writes:
>
>   
> > `defun' is a special form with a special meaning in emacs-lisp
> >     
>
> yes, but "defun" is also in common parlance a "top-level
> form".  these two meanings are congruent but not identical.
> you have to sort of alternatively squint and relax your ears
> to hear the similarity...
>   

If you don't discriminate between termini
top-level-form, function (which is a known name in many
programing languages but not in all) and the special
Emacs Lisp form defun, you will run into confusion when
the difference matters.


>  
>   
> > Think it's disturbing to introduce a different meaning
> > employing the same name.
> >     
>
> you get used to being disturbed w/ a little practice.
>
>   
What about to take it as a chance, not being used to?
> > Certainly a function `beginning-of-top-level-form' is
> > useful. However, it should be callable separate from
> > `beginning-of-defun' and vice versa.
> >     
>
> here is a (self-testable in the right context ;-) toy:
>
> (global-set-key 
>  "\C-\M-a"
>  (defun beginning-of-defun-just-defun-really-i-mean-it! ()
>    (interactive)
>    (let ((beginning-of-defun-function
>           (lambda ()
>             (search-backward "(defun" (point-min) t))))
>      (beginning-of-defun))))
>   

This form will fail, should there be a string "(defun"
somewhere in a docu or other included text before the
real beginning of function.

Also its focus is on the less general form in this context.

Propose a top-down proceeding while re-designing
venerable `beginning-of-defun' function.


beginning-of-top-level-form

beginning-of-form ;; before and under point

beginning-of-function

The latter would - if in Emacs Lisp-mode - be provided with
a spec to indentify the defun-form

>   
> >  `beginning-of-defun' should work right out of the
> > box at least in Emacs Lisp. That's easily to be done -
> > if the need is recognised so far.
> >     
>
> it works for my understanding of "defun".  more importantly,
> my understanding of "defun" is shared by many people, most
> of whom are probably uninclined to add something like the
> above function to emacs.
>
> thi
>
>   

The author of edebug.el at least seems conscious of the
problem. Doesn't seem an accident he named it

edebug-eval-top-level-form

providing just an alias

(defalias 'edebug-defun 'edebug-eval-top-level-form)

Also I read there

(defun edebug-read-top-level-form ()
 (let ((starting-point (point)))
   (end-of-defun)
   (beginning-of-defun)
...

It's not just for fun I entered this
matter. `beginning-of-defun' is buggy - and a lot of
forms which rely on it.


(unless t
 (defun foo ()
   "Explore the right \"(defun-funktion\" "
   (interactive)
   (message "%s" "baz")))
                  ^
M-x beginning-of-defun ==>

(unless t
^  (defun foo ()
   "Explore the right \"(defun-funktion\" "
   (interactive)
   (message "%s" "baz")))


When the [ \t]* as regexp-prefix is set

M-x beginning-of-defun ==>

(unless t
 (defun foo ()
   "Explore the right \"(defun-funktion\" "
   (interactive)
   (message "%s" "baz")))
^

__
Andreas Roehler