Re: Abbrev suggestions - feedback appreciated

[Mathias Dahl <mathias.dahl@gmail.com>]

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On Sun, May 17, 2020 at 12:10 AM Mathias Dahl <mathias.dahl@gmail.com>
wrote:

> >> I think you'd be better served defining a dolist-style macro or
>> >> a mapc-style function to loop over all abbrevs without creating an
>> >> intermediate list.
>> > Sorry, I don't understand what you are suggesting, and why
>> (performance, or
>> > saving memory?).
>>
>> The idea is to avoid the memory allocation, yes.  It should improve
>> performance and reduce the frequency of GC pauses.
>>
>
> I think I don't understand the alternatives here. Firstly, I think I need
> to use
> mapatoms to look for the abbrev names and values. That then, needs to run
> in some kind of loop, for all the active abbrev tables. As I find non-nil
> entries
> in the table, I need to collect those in some "list" of some kind, which I
> return in
> the end. This intermediate list you mention, is that hidden in the dolist
> macro,
> or what is your thinking? And, if so, is the idea to make something
> similar to dolist
> that does "the mapatoms thing" as well?
>
> Here is the function again, for convenience:
>
>  (defun abbrev-get-active-expansions ()
>   "Return a list of all the active abbrev expansions.
> Includes expansions from parent abbrev tables."
>   (let (expansions)
>     (dolist (table (abbrev--active-tables-including-parents))
>       (mapatoms (lambda (e)
>                   (let ((value (symbol-value (abbrev--symbol e table))))
>                     (when value
>                       (push (cons value (symbol-name e)) expansions))))
>                 table))
>     expansions))
>

I gave the mapc approach a naïve try, but I am not sure if it is better:

(defun abbrev-get-active-expansions ()
  "Return a list of all the active abbrev expansions.
Includes expansions from parent abbrev tables."
  (let (expansions)
    (mapc (lambda (table)
            (mapatoms (lambda (e)
                        (let ((value (symbol-value (abbrev--symbol e
table))))
                          (when value
                            (push (cons value (symbol-name e))
expansions))))
                      table))
          (abbrev--active-tables-including-parents))
    expansions))

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