Why isn't the jch's "with-undo-collapse" macro an emacs built-in yet?

Question

I wondered why the jch's with-undo-collapse macro (or something like that) isn't an emacs built-in yet.

Is it safe enough? Is there a built-in alternative?

I mean something that can be applied like in the jcs's example of usage:

(defun test-no-collapse ()
  (interactive)
  (insert "toto")
  (undo-boundary)
  (insert "titi"))

(defun test-collapse ()
  (interactive)
  (with-undo-collapse
    (insert "toto")
    (undo-boundary)
    (insert "titi")))

`M-x report-emacs-bug` as a feature request. Things don't get built-in if no one asks for them. — phils, Mar 01 '19 at 06:16

Stefan · Accepted Answer · 2019-03-03T13:29:16.360

3

There is undo-amalgamate-change-group nowadays. Used for instance in the function viper-adjust-undo in the file lisp/emulators/viper-cmd.el:

(defun test-collapse ()
  (let ((cg (prepare-change-group)))
    (insert "toto")
    (undo-boundary)
    (insert "titi")
    (undo-amalgamate-change-group cg)))

edited Mar 03 '19 at 13:29

answered Mar 01 '19 at 14:19

Stefan

26,154
3
46
84

Could you please post a concrete example of usage of this function using the above`test-collapse` code? I have some difficulty understanding the `undo-amalgamate-change-group` usage. – Gabriele Nicolardi Mar 01 '19 at 15:41
It would be nice to write an `with-undo-collapse` macro that uses `undo-amalgamate-change-group`, since it's more verbose with explicit change-group references. – ideasman42 Dec 16 '19 at 07:37

score 0 · Answer 2 · answered Mar 29 '22 at 00:05

0

Emacs 28 has a built-in macro with-undo-amalgamate.

answered Mar 29 '22 at 00:05

ideasman42

8,375
1
28
105

Why isn't the jch's "with-undo-collapse" macro an emacs built-in yet?

2 Answers2