Being more familiar with Python then elisp, I'd like to evaluate the selection as as Python snipped - as a short-cut to opening a calculator or Python prompt and copy-pasting between them.
Is there a convenient way to evaluate the selection as a Python expression?
So I could type for eg 11**13//7 and replace it with 4931816020561
Posting own answer which mostly works as I'd like (needed some special consideration for evil mode).
While it works well for basic usage, errors will also replace the selection, ideally a nonzero exit code would display as a message instead of putting the error into the editor.
;; See: https://emacs.stackexchange.com/a/34900/2418
;; Wrapper for 'shell-command-on-region', keeps the selection.
(defun 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 (string= evil-state "visual")
(when (eq (evil-visual-type) evil-visual-line)
(evil-visual-select start end 'line)))))
(defun eval-region-as-py ()
"Evaluate selection as a python expression, replacing it with the result"
(interactive)
(shell-command-on-region-and-select
(region-beginning)
(region-end)
"python -c 'import sys; sys.stdout.write(str((eval(sys.stdin.read()))))'" 0 t))
(define-key evil-visual-state-map (kbd "RET") 'eval-region-as-py)
Just select your code and then
C-u M-| python
or
C-u M-x shell-command-on-region python
