Can't assign keys programmatically to bookmarks in a loop

Question

Suppose, we have n bookmarks in the list (n <= 9)

% Bookmark
- --------
1  mark-1                     ~/work/file-1.txt
2  mark-2                     ~/work/file-2.txt
  ...
9  mark-9                     ~/work/file-9.txt

I wanted to programmatically attach key <n> to jump to n-th bookmark.

Code

;get a sorted list of bookmarks
(let ((bookmarks (sort (bookmark-all-names) 'string<))
      (i 1))
  (while bookmarks
    (setq key (number-to-string i))
    ;try to assign key i -> jump-to-bookmark(bookmarks[i])
    (define-key bookmark-bmenu-mode-map
      (kbd key)
      (lambda () (interactive) (bookmark-jump (car bookmarks))))
    ;next bookmark
    (setq bookmarks (cdr bookmarks))
    (setq i (+ i 1))
              ))

Unfortunately, it gives an error:

(wrong-type-argument integer-or-marker-p key)

Answer 1

The issue here is related to the fact that you are using dynamic binding, but trying to access from a lambda a variable that is not in scope anymore (bookmarks). You can fix it by defining the lambda this way:

`(lambda () (interactive) (bookmark-jump (car ',bookmarks))))

You can see an explanation here.

(btw, code will fail when you have more than 9 bookmarks)

This is the modified code that works fine for me:

(let ((bookmarks (sort (bookmark-all-names) 'string<))
      (i 1)
      key)
  (while bookmarks
    (setq key (number-to-string i))
    (define-key bookmark-bmenu-mode-map
      (kbd key)
      `(lambda () (interactive) (bookmark-jump (car ',bookmarks))))
    (setq bookmarks (cdr bookmarks))
    (setq i (+ i 1))))