Try to make Python org-src-mode buffers working with eglot

README.org

@@ -2910,11 +2910,17 @@ Listing [[lst:configure-writegood-mode]] configures [[https://github.com/bnbeckw
 :END:
 
 [[https://github.com/joaotavora/eglot#readme][Emacs polyGLOT (eglot)]] is an Emacs language-server-protocol client that stays
-out of the way.  Listing [[lst:ensure-eglot-installation]] ensures installation of
-[[https://github.com/joaotavora/eglot][eglot]] with minimal configuration and listing [[lst:eglot-maybe-ensure]] starts [[https://github.com/joaotavora/eglot][eglot]]
-in case of proper programming modes and proper directory local variables
-(meaning in presence of a proper [[info:emacs#Directory Variables][.dir-locals.el]] file in the root directory of
-any project using proper programming modes).
+out of the way.  Three listings provide a programming language mode independent
+[[https://github.com/joaotavora/eglot][eglot]] configuration:
+1. Listing [[lst:ensure-eglot-installation]] ensures installation of [[https://github.com/joaotavora/eglot][eglot]] with
+   minimal configuration.
+2. Listing [[lst:eglot-maybe-ensure]] starts [[https://github.com/joaotavora/eglot][eglot]] in case of proper programming
+   modes and proper directory local variables (meaning in presence of a proper
+   [[info:emacs#Directory
+   Variables][.dir-locals.el]] file in the root directory of any project using proper
+   programming modes).
+3. Listing [[lst:setup-python-org-src-mode-for-eglot]] tries to prepare Python
+ =org-src-mode= buffers for use with [[https://github.com/joaotavora/eglot][eglot]].
 
 #+caption[Ensure =eglot= installation]:
 #+caption: Ensure =eglot= installation.
@@ -2935,17 +2941,74 @@ any project using proper programming modes).
 #+name: lst:eglot-maybe-ensure
 #+begin_src emacs-lisp
   (when (fboundp 'eglot-ensure)
-    (defcustom eglot-maybe-derived-modes '(python-mode)
-      "Modes to call `eglot-ensure' in case of proper directory local variables.")
+    (defcustom eglot-maybe-ensure-modes '(python-mode)
+      "Modes where maybe `eglot-ensure' should be or has been called.
+  This may be in the case of proper directory local variables or in
+  the case of proper `org-src-mode' buffers.")
+
+    (defun eglot-maybe-ensure ()
+      (when (and (apply #'derived-mode-p eglot-maybe-ensure-modes)
+                 (assoc 'eglot-workspace-configuration dir-local-variables-alist))
+        (eglot-ensure)))
+
     ;; The two hooks `after-change-major-mode-hook' and
     ;; `hack-local-variables-hook' are OK, but language mode hooks like
     ;; `python-mode-hook' are not.
-    (add-hook 'after-change-major-mode-hook
-              (defun eglot-maybe-ensure ()
-                (when (and (apply #'derived-mode-p eglot-maybe-derived-modes)
-                           (assoc 'eglot-workspace-configuration
-                                  dir-local-variables-alist))
-                  (eglot-ensure)))))
+    (add-hook 'after-change-major-mode-hook #'eglot-maybe-ensure))
+#+end_src
+
+#+caption[Setup Python =org-src-mode= buffers for =eglot=]:
+#+caption: Setup Python =org-src-mode= buffers for =eglot=.
+#+name: lst:setup-python-org-src-mode-for-eglot
+#+begin_src emacs-lisp
+  (when (fboundp 'eglot-ensure)
+    ;; https://www.reddit.com/r/emacs/comments/w4f4u3
+    ;; /using_rustic_eglot_and_orgbabel_for_literate/
+    (defun org-babel-edit-prep:python (info)
+      "Try to setup the `org-mode-src' buffer to make `eglot-ensure' succeed.
+  INFO has a form similar to the return value of
+  `org-babel-get-src-block-info'.  Try to load the tangled file
+  into the `org-src-mode' buffer as well as to narrow the region to
+  the Org-mode source block code before calling `eglot-ensure'."
+      (let ((mark (point))
+            (body (nth 1 info))
+            (filename (expand-file-name (cdr (assq :tangle (nth 2 info))))))
+        (unless (file-readable-p filename)
+          (user-error "Tangled file %s is not readible" filename))
+        (with-temp-buffer
+          (insert-file-contents filename 'visit nil nil 'replace)
+          (unless (search-forward body nil 'noerror)
+            (user-error "Org source block does not occur in tangled file %s"
+                        filename))
+          (when (search-forward body nil 'noerror)
+            (user-error "Org source block occurs twice or more in tangled file %s"
+                        filename)))
+        (goto-char (point-min))
+        (insert-file-contents filename 'visit nil nil 'replace)
+        (let ((max-point (search-forward body))
+              (min-point (search-backward body)))
+          (narrow-to-region min-point max-point))
+        (goto-char mark)
+        (eglot-ensure)))
+
+    (defun undo-eglot-org-babel-edit-prep()
+      "Undo the `eglot' setup by deleting the text hidden by narrowing.
+  This is to advice `org-edit-src-exit' and `org-edit-src-save'."
+      (when (and (apply #'derived-mode-p eglot-maybe-ensure-modes)
+                 (bound-and-true-p org-src-mode)
+                 (buffer-file-name))
+        (save-excursion
+          (goto-char (point-min))
+          (save-restriction
+            (widen)
+            (delete-region (point-min) (point)))
+          (goto-char (point-max))
+          (save-restriction
+            (widen)
+            (delete-region (point) (point-max))))))
+
+    (advice-add 'org-edit-src-exit :before #'undo-eglot-org-babel-edit-prep)
+    (advice-add 'org-edit-src-save :before #'undo-eglot-org-babel-edit-prep))
 #+end_src
 
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