I'd like to use shell-command-on-region on the region, in a way that keeps the selection, even in the case the length of the output changes, and works in regular emacs and in evil mode?
Note, I've already asked this related question which is similar, just not dealing with selection: How to use an external command to modify selected words and lines?
This can be done, I managed to get it working (with help from @wasamasa), notes:
deactivate-mark is nil so Emacs can restore the selection.(evil-visual-select ...) needs to be called.Below is a wrapper for shell-command-on-region that handles re-selection.
;; Wrapper for 'shell-command-on-region', keeps the selection.
(defun my-shell-command-on-region-and-select
(start
end
command
&optional
output-buffer
replace
error-buffer
display-error-buffer
region-noncontiguous-p)
"Wrapper for 'shell-command-on-region', re-selecting the output.
Useful when called with a selection, so it can be modified in-place."
(interactive)
(let ((buffer-size-init (buffer-size)))
(shell-command-on-region
start
end
command
output-buffer
replace
error-buffer
display-error-buffer
region-noncontiguous-p)
(setq deactivate-mark nil)
(setq end (+ end (- (buffer-size) buffer-size-init)))
(set-mark start)
(goto-char end)
(activate-mark)
;; needed for evil line mode
(when (and (boundp evil-state) (string= evil-state "visual"))
(when (eq (evil-visual-type) evil-visual-line)
(evil-visual-select start end 'line)))))
Example call:
(my-shell-command-on-region-keep-region-and-select
(region-beginning) (region-end)
"tr A-Za-z a-zA-Z && echo ' extra text'")
(let (deactivate-mark) ...) is another idiom of that kind that protects the let-bound variable so that changes to it are limited to the body.