Feature Request: Perspective-specific next/prev buffer switch

[Ailrun]

At least I know, perspective doesn't have features that is like switch-to-next-buffer or switch-to-prev-buffer using specific perspective.

In detail, there is no simple way to change C-x <C-left> (switch-to-prev-buffer) to perspective-relative one.
For example, suppose that I have 2 perspective perspA and perspB, and there are 5 buffers in perspA, and there are 7 buffers in perspB. In this case, I can't traverse my buffers only which are in perspA, and while traversing, all buffers of perspB will join to perspA and everything is messed up.

Could you add these features(next/prev) to this wonderful package?

[inigoserna]

I use these functions to achieve the same behaviour you are asking for:

(defun isr/persp-get-buffers-list ()
  "Get filtered list of buffers, sorted alphabetically."
  (sort
   (cl-remove-if '(lambda (b) (if (stringp b) (string-match "^\[* \]" b) t))
                 (mapcar 'buffer-name (persp-buffers persp-curr)))
   'string<))

(defun isr/persp-next-buffer ()
  "My own version of `next-buffer'. Don't show internal buffers."
  (interactive)
  (let ((buffername (buffer-name (current-buffer)))
        (bufferlist (isr/persp-get-buffers-list)))
    (switch-to-buffer (or (cadr (member buffername bufferlist)) (car bufferlist)))))

(defun isr/persp-previous-buffer ()
  "My own version of `next-buffer'. Don't show internal buffers"
  (interactive)
  (let ((buffername (buffer-name (current-buffer)))
        (bufferlist (reverse (isr/persp-get-buffers-list))))
    (switch-to-buffer (or (cadr (member buffername bufferlist)) (car bufferlist)))))

[Ailrun]

@inigoserna
Thx for your info! I will try it!
Why don't you send a PR?

[inigoserna]

IMO it's a personal customization, not something everyone could be interested in.

[Ailrun]

But it's useful to have, isn't it?

[inigoserna]

Well, I use it daily ;)

[Ailrun]

@inigoserna I mean, it's useful, so there's worth to send a PR with this feature, isn't it?

[tonycpsu]

Looking for something like this myself, and the functions above seem to not be compatible with current versions of perspective. I'm getting Symbol’s value as variable is void: persp-curr.

[gcv]

A few thoughts on this.

To address @tonycpsu's comment about @inigoserna's code not working with current Perspective. You can fix it by changing persp-curr to (persp-curr). If that's the functionality you want, that should be enough.

However, I don't think that code really does the right thing with regard to going to the "next" or "previous" buffer. Since it sorts buffers alphabetically, it actually goes to the next or previous buffer in alphabetical order, not in chronological last-viewed order as the Emacs built-in switch-to-next-buffer and switch-to-previous-buffer do.

Writing an implementation of persp-next-buffer and persp-previous-buffer which does the right thing with regard to chronological sorting is tricky. The equivalent Emacs built-ins are quite complex (and IMO have bad behavior with regard to uninteresting and temporary buffers anyway), and I don't see an easy way to make them respect Perspective.

I recently added Perspective-aware implementations of several buffer switchers, in addition to the Ido support which has been available for a long time. See the updated README for details. Would those work instead of a mechanism for iterating through all of a perspective's buffers in a given window?

[gcv]

Closing this unless someone convinces me that Perspective-aware buffer switchers are inadequate, and that there's a reasonably simple implementation path.