Make slime repl output read-only

[anlsh]

I found it a bit jarring that it was possible to edit past output in the slime repl, so I messed around a bit & made the output read-only.

I should note that I don't know why rear-nonsticky was set as face, and therefore the new value of t is suspect: it doesn't seem to have changed anything visible & the tests all pass (except for one which fails even on the current master). However, I found that unless I changed the value for rear-nonsticky, formatting with read-only t would complain about some sort of "timer error" and never display the input prompt or cursor after any output had been written to the repl.

I was also hoping to do the same for the results returned by functions instead of just printed output: after trying to make analogous changes to slime-repl.el/slime-repl-emit-result, I figured out that this function wasn't actually involved in emitting results. The function actually responsible is slime-presentations.el/slime-presentation-write-result. Unfortunately trying the same trick makes the repl very slow to display evaluation results & seems to reset the font color.

Anyways. I thought I'd submit what I had. Perhaps someone who knows what they're doing could finish the job for evaluation results?

[luismbo]

This is a bit of an Emacs tradition with repls. ielm and eshell, for instance, have the same behaviour. I'm not sure why that is.

[joaotavora]

This is a bit of an Emacs tradition with repls. ielm and eshell, for instance, have the same behaviour. I'm not sure why that is.

It's sort of by design in comint.el, and there is prior art for fixing those. I sympathise with this, and the relative sanity comint.el offers prompted me to choose it for SLY's REPL (sorry for the plug).

[luismbo]

(defun my-comint-preoutput-turn-buffer-read-only (text)
  (propertize text 'read-only t))

(add-hook 'comint-preoutput-filter-functions 'my-comint-preoutput-turn-buffer-read-only)

is this what you're suggesting for fixing the issue in comint-based repls?

[joaotavora]

is this what you're suggesting for fixing the issue in comint-based repls?

Something like that, yes. But I don't think SLIME's REPL is comint-based (maybe I'm wrong). By "sympathise" I mean I sympathise with the OP's report.

[easye]

Something like that, yes. But I don't think SLIME's REPL is comint-based (maybe I'm wrong). By "sympathise" I mean I sympathise with the OP's report.

I would love a toggle here, to switch between the traditional mode and the "safety" mode. Especially on presentations that can be inspected, as many is the time I had to re-run the code to get a new presentation to inspect.

[lukego]

Maybe read-only could be set to the value of some new variable, e.g. slime-repl-output-read-only, which the user can configure? That way the default behavior would be the same (for now) but you could get read-only by tweaking your .emacs.

[lukego]

Looks like some spaces-to-tabs conversions sneaked in here. You might like to run untabify on the buffer to put that back and maybe even make that default with an emacs config line like

(add-hook 'lisp-mode-hook (defun my-lisp-mode-hook () (setq indent-tabs-mode nil)))

[spwhitton]

Hope this can be optional; I find the editability more intuitive as an Eshell user.