Re: [BUG] ox-html does not export captions of source blocks without language

[Ihor Radchenko]

Ihor Radchenko <yantar92@posteo.net> writes:

> Here is the plan to resolve this issue:
>
> 1. We update the manual allowing src blocks to have empty language spec

See the attached patch.

> 2. We update org-syntax document

It turned out to be unnecessary.  org-syntax document already declares
block DATA to be optional:

#+begin_name [DATA]
#+end_name

See https://orgmode.org/worg/org-syntax.html#Blocks

Code blocks fall within a subset of this rule.

> 3. We change org-html-src-block to add caption to src blocks without lang

See the attached patch.

>From a7c5aa3431cc1946aa7f8055c39e18e5afc4cef4 Mon Sep 17 00:00:00 2001
Message-Id: 
<a7c5aa3431cc1946aa7f8055c39e18e5afc4cef4.1673863743.git.yantar92@posteo.net>
From: Ihor Radchenko <yantar92@posteo.net>
Date: Mon, 16 Jan 2023 12:59:47 +0300
Subject: [PATCH 1/2] org-manual.org: Clarify that LANGUAGE may be omitted in
 code blocks

* doc/org-manual.org (Structure of Code Blocks):
(Editing Source Code): Clarify that <language> is optional.  Link to
possible consequences of <language> being omitted.
---
 doc/org-manual.org | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/doc/org-manual.org b/doc/org-manual.org
index 4466af8e4..c241e170f 100644
--- a/doc/org-manual.org
+++ b/doc/org-manual.org
@@ -17313,9 +17313,16 @@ ** Structure of Code Blocks
 - =<language>= ::
 
   #+cindex: language, in code blocks
-  Mandatory.  It is the identifier of the source code language in the
+  Optional.  It is the identifier of the source code language in the
   block.  See [[*Languages]], for identifiers of supported languages.
 
+  When =<language>= identifier is omitted, the block also cannot
+  have =<switches>= and =<header arguments>=.
+
+  Language identifier is also used to fontify code blocks in Org
+  buffers, when ~org-src-fontify-natively~ is set to non-~nil~.  See
+  [[*Editing Source Code]].
+
 - =<switches>= ::
 
   #+cindex: switches, in code blocks
@@ -18951,6 +18958,9 @@ ** Editing Source Code
   header line, then the edit buffer uses that major mode.  Use this
   variable to arbitrarily map language identifiers to major modes.
 
+  When language identifier is omitted in the src block, Org mode's
+  behavior is undefined.
+
 - ~org-src-window-setup~ ::
 
   #+vindex: org-src-window-setup
@@ -18976,10 +18986,13 @@ ** Editing Source Code
 
 #+vindex: org-src-fontify-natively
 #+vindex: org-src-block-faces
-Set ~org-src-fontify-natively~ to non-~nil~ to turn on native code
-fontification in the /Org/ buffer.  Fontification of code blocks can
-give visual separation of text and code on the display page.  To
-further customize the appearance of ~org-block~ for specific
+Fontification of code blocks can give visual separation of text and
+code on the display page.  Set ~org-src-fontify-natively~ to non-~nil~
+to turn on native code fontification in the /Org/ buffer.  The
+fontification follows the major mode used to edit the code block (see
+~org-src-lang-modes~ above).
+
+To further customize the appearance of ~org-block~ for specific
 languages, customize ~org-src-block-faces~.  The following example
 shades the background of regular blocks, and colors source blocks only
 for Python and Emacs Lisp languages.
-- 
2.39.0

>From 8c832d374066bbba430dc21a6b4fb098361c44a9 Mon Sep 17 00:00:00 2001
Message-Id: 
<8c832d374066bbba430dc21a6b4fb098361c44a9.1673863743.git.yantar92@posteo.net>
In-Reply-To: 
<a7c5aa3431cc1946aa7f8055c39e18e5afc4cef4.1673863743.git.yantar92@posteo.net>
References: 
<a7c5aa3431cc1946aa7f8055c39e18e5afc4cef4.1673863743.git.yantar92@posteo.net>
From: Ihor Radchenko <yantar92@posteo.net>
Date: Mon, 16 Jan 2023 13:04:01 +0300
Subject: [PATCH 2/2] org-html-src-block: Treat code blocks without LANG
 equally
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

* lisp/ox-html.el (org-html-src-block): Do not treat src blocks
without LANG as example blocks.  Instead, export them using "nil"
language.  This way, such src blocks will get captions, unlike example
blocks.

The new behavior is consistent with ox-latex and ox-ascii.

Reported-by: Johan Bolmsjö <org-mode@johan.bitmaster.se>
Link: https://orgmode.org/list/87zgb90win.fsf@localhost
---
 lisp/ox-html.el | 52 ++++++++++++++++++++++++-------------------------
 1 file changed, 26 insertions(+), 26 deletions(-)

diff --git a/lisp/ox-html.el b/lisp/ox-html.el
index 7b79c57d4..5e58ccba3 100644
--- a/lisp/ox-html.el
+++ b/lisp/ox-html.el
@@ -3616,32 +3616,32 @@ (defun org-html-src-block (src-block _contents info)
           (klipsify  (and  (plist-get info :html-klipsify-src)
                             (member lang '("javascript" "js"
                                           "ruby" "scheme" "clojure" "php" 
"html")))))
-      (if (not lang) (format "<pre class=\"example\"%s>\n%s</pre>" label code)
-       (format "<div class=\"org-src-container\">\n%s%s\n</div>"
-               ;; Build caption.
-               (let ((caption (org-export-get-caption src-block)))
-                 (if (not caption) ""
-                   (let ((listing-number
-                          (format
-                           "<span class=\"listing-number\">%s </span>"
-                           (format
-                            (org-html--translate "Listing %d:" info)
-                            (org-export-get-ordinal
-                             src-block info nil #'org-html--has-caption-p)))))
-                     (format "<label class=\"org-src-name\">%s%s</label>"
-                             listing-number
-                             (org-trim (org-export-data caption info))))))
-               ;; Contents.
-               (if klipsify
-                   (format "<pre><code class=\"src 
src-%s\"%s%s>%s</code></pre>"
-                           lang
-                           label
-                           (if (string= lang "html")
-                               " data-editor-type=\"html\""
-                             "")
-                           code)
-                 (format "<pre class=\"src src-%s\"%s>%s</pre>"
-                          lang label code)))))))
+      (format "<div class=\"org-src-container\">\n%s%s\n</div>"
+             ;; Build caption.
+             (let ((caption (org-export-get-caption src-block)))
+               (if (not caption) ""
+                 (let ((listing-number
+                        (format
+                         "<span class=\"listing-number\">%s </span>"
+                         (format
+                          (org-html--translate "Listing %d:" info)
+                          (org-export-get-ordinal
+                           src-block info nil #'org-html--has-caption-p)))))
+                   (format "<label class=\"org-src-name\">%s%s</label>"
+                           listing-number
+                           (org-trim (org-export-data caption info))))))
+             ;; Contents.
+             (if klipsify
+                 (format "<pre><code class=\"src src-%s\"%s%s>%s</code></pre>"
+                         lang ; lang being nil is OK.
+                         label
+                         (if (string= lang "html")
+                             " data-editor-type=\"html\""
+                           "")
+                         code)
+               (format "<pre class=\"src src-%s\"%s>%s</pre>"
+                        ;; Lang being nil is OK.
+                        lang label code))))))
 
 ;;;; Statistics Cookie
 
-- 
2.39.0

-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
Support Org development at <https://liberapay.com/org-mode>,
or support my work at <https://liberapay.com/yantar92>