How to set "nojoinspaces" in evil mode

Question

In vim, you can :set nojoinspaces to prevent J from adding a space when joining lines that end in a period. How do I set this in evil mode? I'm using Doom emacs, if that is relevant.

Answer 1

What you need is the function evil-join-whitespace, and a key binding for that. In normal Emacs + evil, this is g J.

In your case, you need to add a suitable key, e.g C-c J, with some code in your ~/doom.d/config.el or where the config.el file is:

(evil-define-key* 'normal 'global
    (kbd "C-c J" #'evil-join-whitespace))
;; or this:
(after! evil
    (map! :n "C-c J" #'evil-join-whitespace))

See the files ~/.emacs.d/docs/faq.org and ~/.emacs.d/docs/examples.org. NB: not tested.

Answer 2

Although I am unable to reproduce the behavior (of evil-join adding an extra space after a period), here is a solution that should emulate vim's nojoinspace behavior.

Inspecting the function evil-join we find that it uses the function join-line without adding the option for 'nojoinspaces functionality'. Also, join-line (which is an alias for delete-indentation) does not offer such functionality. However, I would say such functionality can be added by advising either evil-join or join-line.

It is not straightforward to create a 'succesful' advice for evil-join or join-line when applying it to multiple lines. Luckily, when applying evil-join to multiple lines, it simply applies join-line to a single line multiple times. Therefore, it is easiest to simply advise join-line e.g. as follows

(defun evil-nojoinspaces-ad (&rest _)
    (when (looking-back "\\.")
        (delete-char 1)))

(advice-add 'delete-indentation :after #'evil-nojoinspaces-ad)