Re: Errors in interactive commands

[Andreas Röhler]

Am 03.08.2011 11:09, schrieb Stephen J. Turnbull:
> Andreas Röhler writes:
>
>   >  Useful return values of "forward-" is important for a wide range of
>   >  things, not just to serve several specific cases.
>
> Unfortunately, when there are "several specific cases", they often
> have different requirements.  Your term "useful" is undefined,

obviously

 and you
> need to define it and show that there is a unified definition powerful
> enough to make it worthwhile to introduce a backward-incompatible
> change.
>
> One way to present such definitions is to describe use cases.  Mine is
> an important one: "iterating over a presumed-to-be array-structured
> buffer, executing a destructive action on each element of the structure."
>
> On the other hand, your pseudo-code is way too "pseudo" to be useful
> to me.  Please *define* the functions that check and update
> "delete-second-state".  I think you will find it is rather hard to do
> as efficiently as my code, without duplicating my code (perhaps
> implicitly).

for example the implemented form forward-word already sends nil, not 
error, when buffer-end is reached. Remains still to get it messaged.

Thus implemented forward-word would allow a similar writing as below.
However, that is not convention in Emacs Lisp yet.

Also the return of `t' isn't as useful as `point' IMHO

Maybe the following function using `(setq erg'

might provide sense onto the terms missed definition:

(defun my-collects ()
 "Report and return all word boundaries in current buffer, a list. "
  (interactive)
  (goto-char (point-min))
  (let ((positions-reached nil)
        (word-bounderies nil)
        erg bnds)
    (while (setq erg (ar-forward-word-atpt))
      (add-to-list 'positions-reached erg)
      (setq bnds (ar-bounds-of-word-atpt))
      (add-to-list 'word-bounderies bnds))
    (when (interactive-p) (message "positions-reached: %s" 
positions-reached))
    (when (interactive-p) (message "word-bounderies: %s" word-bounderies))
;;    positions-reached
    word-bounderies
    ))

Just try to write that with means commonly available.

To get

(ar-forward-word-atpt)

thing-at-point-utils.el and thingatpt-utils-base.el

from
https://launchpad.net/s-x-emacs-werkstatt/

is needed

Andreas

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