[Pre-PATCH] Add new :lexical header argument

[Evgenii Klimov <eugene.dev@lipklim.org>]

[-- Attachment #1: Type: text/plain, Size: 1053 bytes --]

Hi, here I propose new header argument to enable scope change
(lexical/dynamic binding) of the tangled file.  We have :shebang header
argument and the new one behaves similarly.

If you like the idea I think we should discuss the following:
- should we allow to set it for non-elisp blocks?  e.g. :shebang is not
  restricted and `elisp-enable-lexical-binding' is smart enough to use
  the comment symbol appropriate to the context. 
- should it be :lexical or :scope.  :lexical is long to type, but boolean
  and clear; scope is shorter, but the user will have to type
  "dynamic/lexical" or "dyn/lex".
- should we add the third option of the argument to explicitly forbid
  lexical binding?  E.g. if we a have source block that rely on the
  dynamic binding but it could be used in another block with lexical
  binding via noweb. I'm not sure that it's worth the effort.
- which default value to choose?  Currently if you tangle it would be
  dynamic, but lexical binding is the future.

After all I'll add tests and update Changelog/Docs if needed.


[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: 0001-ob-tangle.el-Add-new-lexical-header-argument.patch --]
[-- Type: text/x-diff, Size: 3158 bytes --]

From 3ad56137cb709182dc1bc242cd80a1474078cb95 Mon Sep 17 00:00:00 2001
From: Evgenii Klimov <eugene.dev@lipklim.org>
Date: Thu, 13 Jul 2023 18:16:08 +0100
Subject: [PATCH] ob-tangle.el: Add new :lexical header argument

* lisp/ob-tangle.el (org-babel-tangle-use-lexical-binding): Add
new customization variable.
(org-babel-tangle): Add ability to enable lexical binding in
tangled file.

* lisp/ob-core.el (org-babel-common-header-args-w-values): Add new
:lexical header argument.

Previously one could achieve this manually, but 1) had to keep in mind
to hold this source block top-most, 2) couldn't use comment header
argument, as `lexical-binding' variable must be set in the first line
of a file.
---
 lisp/ob-core.el   |  1 +
 lisp/ob-tangle.el | 15 +++++++++++++--
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/lisp/ob-core.el b/lisp/ob-core.el
index 47410b53f..c1801a677 100644
--- a/lisp/ob-core.el
+++ b/lisp/ob-core.el
@@ -437,6 +437,7 @@ then run `org-babel-switch-to-session'."
     (sep	. :any)
     (session	. :any)
     (shebang	. :any)
+    (lexical    . ((yes no)))
     (tangle	. ((tangle yes no :any)))
     (tangle-mode . ((#o755 #o555 #o444 :any)))
     (var	. :any)
diff --git a/lisp/ob-tangle.el b/lisp/ob-tangle.el
index 1274d0db7..916dd8489 100644
--- a/lisp/ob-tangle.el
+++ b/lisp/ob-tangle.el
@@ -76,6 +76,11 @@ then the name of the language is used."
   :group 'org-babel-tangle
   :type 'boolean)
 
+(defcustom org-babel-tangle-use-lexical-binding nil
+  "Enable lexical binding in tangled file by default."
+  :group 'org-babel-tangle
+  :type 'boolean)
+
 (defcustom org-babel-post-tangle-hook nil
   "Hook run in code files tangled by `org-babel-tangle'."
   :group 'org-babel-tangle
@@ -262,7 +267,7 @@ expression."
 	     (when file-name
                (let ((lspecs (cdr by-fn))
 		     (fnd (file-name-directory file-name))
-		     modes make-dir she-banged lang)
+		     modes make-dir she-banged scoped lang)
 	         ;; drop source-blocks to file
 	         ;; We avoid append-to-file as it does not work with tramp.
 	         (with-temp-buffer
@@ -273,6 +278,9 @@ expression."
 			     (get-spec (lambda (name) (cdr (assq name (nth 4 spec)))))
 			     (she-bang (let ((sheb (funcall get-spec :shebang)))
 				         (when (> (length sheb) 0) sheb)))
+                             (lexicalp (or (string-equal (funcall get-spec :lexical)
+                                                         "yes")
+                                           org-babel-tangle-use-lexical-binding))
 			     (tangle-mode (funcall get-spec :tangle-mode)))
 		        (unless (string-equal block-lang lang)
 			  (setq lang block-lang)
@@ -294,7 +302,10 @@ expression."
 		        (when (and she-bang (not she-banged))
 			  (insert (concat she-bang "\n"))
 			  (setq she-banged t))
-		        (org-babel-spec-to-string spec)
+                        (org-babel-spec-to-string spec)
+		        (when (and lexicalp (not scoped))
+			  (save-excursion (elisp-enable-lexical-binding))
+			  (setq scoped t))
 		        (setq block-counter (+ 1 block-counter))))
 		    lspecs)
 		   (when make-dir
-- 
2.34.1