Utilizing emacs mykie.el[https://github.com/yuutayamada/mykie-el] to temporarily remember text/buffer to each number. Past text or switch buffer from registered number.

emacs mykie.el sample2

(require 'mykie)

;;; Temporarily remember any text/buffer
;; Example.
;; Region an area -> Copy & Regist [M-5 w] -> Past [M-5 y]
;; Region an area -> Copy & Regist [M-3 w] -> Past [M-3 y]
;; Regist buffer [M-3 B]   -> Switch buffer [M-3 b]
;; Regist buffer [M-8 3 B] -> Switch buffer [M-8 3 b]

;; Describe list
;; M-x my-keep-describe-text
;; M-x my-keep-describe-buffer

(add-to-list 'mykie:conditions '(when (numberp current-prefix-arg) :M-N))

(setq my-keep-text-list (make-hash-table :test 'eq))
(setq my-keep-buffer-list (make-hash-table :test 'eq))

(defun my-keep-text-copy ()
  (interactive)
  (when mark-active
    (puthash current-prefix-arg
             (buffer-substring-no-properties
              (region-beginning) (region-end)) my-keep-text-list)
    (deactivate-mark)
    (message (format "Copied! |%d|" current-prefix-arg))))

(defun my-keep-text-paste ()
  (interactive)
  (let (($text (gethash current-prefix-arg my-keep-text-list)))
    (if $text
        (insert $text)
      (message (format "%s" "Not found!")))))

(defun my-keep-buffer-clip ()
  (interactive)
  (let (($buffer (buffer-name (current-buffer))))
    (puthash current-prefix-arg $buffer  my-keep-buffer-list)
    (message (format "`%s' is clipped! |%d|" $buffer current-prefix-arg))))

(defun my-keep-buffer-switch ()
  (interactive)
  (let (($buffer (gethash current-prefix-arg my-keep-buffer-list)))
    (if $buffer
        (switch-to-buffer $buffer)
      (message (format "%s" "Not found!")))))

(defun my-keep-describe ($hash)
  (let* (($list (loop for k being hash-key in $hash
                      using (hash-values v)
                      collect (cons k v)))
         ($describe (sort* $list '< :key 'car))
         $return)
    (dolist ($x $describe)
      (setq $return (concat $return (format "%02d: %s\n"
                                            (car $x)
                                            (replace-regexp-in-string
                                             "\n" "\n    "
                                             (cdr $x))))))
    (message $return)))
(defun my-keep-describe-text ()
  (interactive) (my-keep-describe my-keep-text-list))
(defun my-keep-describe-buffer ()
  (interactive) (my-keep-describe my-keep-buffer-list))

(mykie:set-keys 'with-self-key
                "w" :M-N '(my-keep-text-copy)
                "y" :M-N '(my-keep-text-paste)
                "B" :M-N '(my-keep-buffer-clip)
                "b" :M-N '(my-keep-buffer-switch))