Re: [Emacs-diffs] master 75d9a55: Fix bug 32543

[Stefan Monnier]

> +(defun occur--parse-occur-buffer()
> +  "Retrieve a list of the form (BEG END ORIG-LINE BUFFER).
> +BEG and END define the region.
> +ORIG-LINE and BUFFER are the line and the buffer from which
> +the user called `occur'."
> +  (save-excursion
> +    (goto-char (point-min))
> +    (let ((buffer (get-text-property (point-at-bol) 'occur-title))
> +          (beg-pos (get-text-property (point-at-bol) 'region-start))
> +          (end-pos (get-text-property (point-at-bol) 'region-end))
> +          (orig-line (get-text-property (point-at-bol) 'current-line))
> +          beg-line end-line)
> +      (list beg-pos end-pos orig-line buffer))))

I'm curious here:
- Why use (point-at-bol) since we just moved to (point-min) and hence we
  know that (point-at-bol) == (point-min) == (point)?
- why store this info in text-properties rather than in buffer-local variables?

> +    (let* ((region (occur--parse-occur-buffer))
> +           (region-start (nth 0 region))
> +           (region-end (nth 1 region))
> +           (orig-line (nth 2 region))
> +           (buffer (nth 3 region))
> +           (regexp (car occur-revert-arguments)))

Here you could have used pcase-let:

    (pcase-let ((`(,region-start ,region-end ,orig-line ,buffer)
                 (occur--parse-occur-buffer))
                (regexp (car occur-revert-arguments)))

> +      (with-current-buffer buffer
> +        (when (wholenump orig-line)
> +          (goto-char 1)

I'd recommend `point-min` instead of 1 here.

> +          (forward-line (1- orig-line)))
> +        (save-excursion
> +          (if region
> +              (occur regexp nil (list (cons region-start region-end)))
> +            (apply 'occur-1 (append occur-revert-arguments (list 
> (buffer-name))))))))))

`region` is the list which holds (among other things) `buffer`, so if we
successfully entered (with-current-buffer buffer ...) I can't see how
`region` could be nil.


        Stefan