Re: Can we add a delete-match function to subr(-x).el?

[Paul W. Rankin]

On Sun, Jan 26 2020, Stefan Monnier wrote:
>>       (when (consp (match-data))
>
> This allocates N cons cells just to test if there's something and in
> practice there's basically *always* something (the match data keeps
> info about the last successful match, so even if your last match was
> a failure, `match-data` won't be nil]).

I figured this was a waste, just wanted it to look more thorough.

Would this be better as a macro?

    (defmacro delete-match (&optional subexp)
      "Delete text matched by last search.

    Optional argument SUBEXP specifies the subexpression to delete,
    or delete the entire match."
      (list 'unless subexp (list 'setq subexp 0))
      (list 'delete-region (list 'match-beginning subexp)
                           (list 'match-end subexp)))

I like this because of this:

    (macroexpand-all
     '(while (re-search-forward "foo\\(ba[rz]\\)" nil t)
        (delete-match 1)))

    => (while (re-search-forward "foo\\(ba[rz]\\)" nil t)
         (delete-region (match-beginning 1) (match-end 1)))