> `delete-trailing-whitespace-mode` was introduced in commit 8a19c249f81.
> Should there also be a `global-delete-trailing-whitespace-mode`?
> This would allow
> (global-delete-trailing-whitespace-mode 1)
> and turning it off in an individual buffer with
> (delete-trailing-whitespace-mode -1)
To define such a mode, we'll need to know when to enable it and when
not: I'd be surprised if adding `delete-trailing-whitespace` globally
to `before-save-hook` doesn't cause problems in various circumstances.
I don't have enough experience with that, so I'll let others decide if
and how to do it.
FWIW, this is how I manage that and even then I might enable it for markdown mode:
(defun my/before-save-hook ()
"Delete trailing white space before saving a buffer, except `markdown-mode'."
(unless (derived-mode-p 'markdown-mode)
(delete-trailing-whitespace)))
(add-hook 'before-save-hook #'my/before-save-hook)
I suppose an exclusion mode list or some other conditionals could be baked into the mode.