Subject: bug#67000: 30.0.50; [PATCH] Add support for reading/writing IELM input history

From: Stefan Kangas <[email-masked]>
Date: Mon, 8 Jan 2024 11:51:39 -0800

Simen Heggestøyl <[email-masked]> writes:

> From a2322770acb6bceab36224989cbbe9b777312997 Mon Sep 17 00:00:00 2001
> From: =?UTF-8?q?Simen=20Heggest=C3=B8yl?= <[email-masked]>
> Date: Wed, 8 Nov 2023 16:08:08 +0100
> Subject: [PATCH] Add support for reading/writing IELM input history
>
> * lisp/ielm.el (inferior-emacs-lisp-mode): Add support for
> reading/writing input history.
> (ielm--history-file-name): Name of the file to read/write IELM input
> history.
> ---
>  etc/NEWS     |  5 +++++
>  lisp/ielm.el | 12 ++++++++++++
>  2 files changed, 17 insertions(+)
>
> diff --git a/etc/NEWS b/etc/NEWS
> index c3d777b971f..b62976143d2 100644
> --- a/etc/NEWS
> +++ b/etc/NEWS
> @@ -1228,6 +1228,11 @@ chat buffers use by default.
>  *** New command 'customize-dirlocals'.
>  This command pops up a buffer to edit the settings in ".dir-locals.el".
>
> +** IELM
> +
> +---
> +*** IELM now remembers input history between sessions.
> +
>  
>  * New Modes and Packages in Emacs 30.1
>
> diff --git a/lisp/ielm.el b/lisp/ielm.el
> index 777aebb70cf..6d4a11c1c28 100644
> --- a/lisp/ielm.el
> +++ b/lisp/ielm.el
> @@ -152,6 +152,10 @@ ielm-header
>  \\[describe-mode] for help.\n"
>    "Message to display when IELM is started.")
>
> +(defvar ielm--history-file-name
> +  (locate-user-emacs-file "ielm-history.eld")
> +  "Name of the file to read/write IELM input history.")

On closer thought, I think this should be a defcustom.

See `lua-ts-inferior-history' and `sql-input-ring-file-name' for
example.

I also think nil might as well be a valid value which disables history
altogether (maybe users don't want that for some reason, let's say
privacy or whatever).

And the defcustom should be mentioned in NEWS, too.

>  (defvaralias 'inferior-emacs-lisp-mode-map 'ielm-map)
>  (defvar-keymap ielm-map
>    :doc "Keymap for IELM mode."
> @@ -605,6 +609,11 @@ inferior-emacs-lisp-mode
>              #'ielm-indirect-setup-hook 'append t)
>    (setq comint-indirect-setup-function #'emacs-lisp-mode)
>
> +  ;; Input history
> +  (setq-local comint-input-ring-file-name ielm--history-file-name)
> +  (setq-local kill-buffer-hook #'comint-write-input-ring)
> +  (comint-read-input-ring t)
> +
>    ;; A dummy process to keep comint happy. It will never get any input
>    (unless (comint-check-proc (current-buffer))
>      ;; Was cat, but on non-Unix platforms that might not exist, so
> @@ -631,6 +640,9 @@ inferior-emacs-lisp-mode
>      (set-marker comint-last-input-start (ielm-pm))
>      (set-process-filter (get-buffer-process (current-buffer)) 'comint-output-filter)))
>
> +(unless noninteractive
> +  (add-hook 'kill-emacs-hook #'comint-write-input-ring))
> +

I'm not so sure about this part.  If this is correct, why should it be
defined here, and not, say, in comint.el?  It seems like a separate,
unrelated change.  What am I missing?

>  (defun ielm-get-old-input nil
>    ;; Return the previous input surrounding point
>    (save-excursion
> --
> 2.39.2