Re: Printing alist pairs to a dedicated buffur

[Heime]

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On Thursday, April 25th, 2024 at 6:48 PM, Emanuel Berg <incal@dataswamp.org> 
wrote:

> Manuel Giraud via Users list for the GNU Emacs text editor wrote:
> 
> > > This is how I am filling my alist named tema-lugar
> > > 
> > > (defun tema-mark (kfrz)
> > > "Associate line number at cursor position with key phrase KFRZ."
> > > (interactive "sString: ")
> > > 
> > > (let ( (lnum (line-number-at-pos)) )
> > > 
> > > (setq-local tema-lugar
> > > (append tema-lugar
> > > (list (cons kfrz lnum)))) ))
> > 
> > Maybe your error comes from this `setq-local'. I have used` defvar' which 
> > will create a global (i.e. visible everywhere
> > in Emacs) variable. `setq-local' or` defvar-local' are used
> > for buffer-local variables. Buffer-local variables are
> > visible only from the buffer they were created.
> 
> 
> Don't use `defvar' if it can be avoided as that creates global 
> dynamic/special variables,` setq' creates global
> static/lexical variables which isn't much better - unless
> there is a variable by that name present, then that is used
> instead. That kind of `setq' use is not wrong, actually it is good. 

So it is actually good, but then still make a commotion about it.
This way of commenting in not productive at all.

> But yes, variables in Emacs are complicated and one problem is that 
> so much is dependent on the situation while the commands look the 
> same. Anyway here is an interesting case, a combination of a for 
> and while loop, and we see the kind of good` setq' use I mean,
> which do not create a global variable but sets an existing
> one, "lst", instead.
> 
> (defun count-list (lst)
> (cl-loop
> with res = ()
> for l in lst while lst do
> (push (list (cl-count l lst) l) res)
> (setq lst (cl-remove l lst))
> finally return (cl-sort res #'>= :key #'car) ))
> 
> 
> ;; (count-list '(a b c d e a b c d a b c a b a))
> ;; -> ((5 a) (4 b) (3 c) (2 d) (1 e))

My defvar is used to store values that I need to access 
when I am working on a buffer.  I can add to it as I modify
the buffer, or delete from it.  I cannot see why all this 
fuss not to use global variables.