bug#55329: [PATCH] Choose latex environment for table.el export

bug#55329: [PATCH] Choose latex environment for table.el export

[Vladimir Nikishkin]

Dear Emacs Developers,

Please, consider this patch for inclusion.
This patch slightly generalises the way Emacs' table.el handles
latex export.
Currently, the export always uses the "tabular" environment.
This patch adds a customize option to select a different one, and
adds one built-in suggestion of "longtable", which should be
perfectly compatible with "tabular".

The patch creates 1 new customize variable:
1. table-latex-environment

And changes the following 2 functions:
1. table--generate-source-epilogue
2. table--generate-source-prologue

#+begin_src patch
diff --git a/lisp/textmodes/table.el b/lisp/textmodes/table.el
index 2175900194..eafa3e7b3c 100644
--- a/lisp/textmodes/table.el
+++ b/lisp/textmodes/table.el
@@ -753,6 +753,18 @@ table-html-cell-attribute
   :type 'string
   :group 'table)

+(defcustom table-latex-environment "tabular"
+  "Which tabular-compatible environment to use when generating latex.
+tabular and longtable are known to work."
+  :tag "Latex environment used to export tables"
+  :type '(choice
+	  (const :tag "tabular" "tabular")
+	  (const :tag "longtable"  "longtable")
+          string)
+  :group 'table
+  :local t)
+
 (defcustom table-cals-thead-rows 1
   "Number of top rows to become header rows in CALS table."
   :tag "CALS Header Rows"
@@ -3025,7 +3037,7 @@ table--generate-source-prologue
 		"")))
      ((eq language 'latex)
       (insert (format "%% This LaTeX table template is generated by emacs %s\n" emacs-version)
-	      "\\begin{tabular}{|" (apply #'concat (make-list (length col-list) "l|")) "}\n"
+	      "\\begin{" table-latex-environment "}{|" (apply #'concat (make-list (length col-list) "l|")) "}\n"
 	      "\\hline\n"))
      ((eq language 'cals)
       (insert (format "<!-- This CALS table template is generated by emacs %s -->\n" emacs-version)
@@ -3051,7 +3063,7 @@ table--generate-source-epilogue
      ((eq language 'html)
       (insert "</table>\n"))
      ((eq language 'latex)
-      (insert "\\end{tabular}\n"))
+      (insert "\\end{" table-latex-environment "}\n"))
      ((eq language 'cals)
       (set-marker-insertion-type (table-get-source-info 'colspec-marker) t) ;; insert before
       (save-excursion
#+end_patch

The copyright disclaimer has been signed by me and submitted to FSF
last August.

-- 
Your sincerely,
Vladimir Nikishkin (MiEr, lockywolf)
(Laptop)

bug#55333: [PATCH] Choose latex environment for table.el export

[Lars Ingebrigtsen]

Vladimir Nikishkin
<for.emacs-table.el-environment-patch_2022-05-09@lockywolf.net> writes:

> Please, consider this patch for inclusion.
> This patch slightly generalises the way Emacs' table.el handles
> latex export.
> Currently, the export always uses the "tabular" environment.
> This patch adds a customize option to select a different one, and
> adds one built-in suggestion of "longtable", which should be
> perfectly compatible with "tabular".

Thanks; makes sense to me, so I've pushed it to Emacs 29 (with some
small changes).

By the way, the patch didn't apply directly, so it seems like something
had mangled it in transmission.  For future patches, it's probably
better to include patches as attachments.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#55329: [PATCH] Choose latex environment for table.el export

[Eli Zaretskii]

> From: Vladimir Nikishkin  <lockywolf@gmail.com>
> Date: Mon, 09 May 2022 10:30:57 +0800
> 
> The patch creates 1 new customize variable:
> 1. table-latex-environment
> 
> And changes the following 2 functions:
> 1. table--generate-source-epilogue
> 2. table--generate-source-prologue

Thanks.  A couple of minor nits:

> +(defcustom table-latex-environment "tabular"
> +  "Which tabular-compatible environment to use when generating latex.
> +tabular and longtable are known to work."

I'm not sure I understand the purpose of the last sentence, nor what
it adds to the doc string.

Also, perhaps we should prefer symbol values, not string values here?
Symbols are easier to compare and harder to make mistakes.

bug#55329: [PATCH] Choose latex environment for table.el export

[Vladimir Nikishkin]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Vladimir Nikishkin  <lockywolf@gmail.com>
>> Date: Mon, 09 May 2022 10:30:57 +0800
>> 
>> The patch creates 1 new customize variable:
>> 1. table-latex-environment
>> 
>> And changes the following 2 functions:
>> 1. table--generate-source-epilogue
>> 2. table--generate-source-prologue
>
> Thanks.  A couple of minor nits:
>
>> +(defcustom table-latex-environment "tabular"
>> +  "Which tabular-compatible environment to use when generating latex.
>> +tabular and longtable are known to work."
>
> I'm not sure I understand the purpose of the last sentence, nor what
> it adds to the doc string.
>
> Also, perhaps we should prefer symbol values, not string values here?
> Symbols are easier to compare and harder to make mistakes.

I think this is a duplicate bug, I am sorry. This patch has already been
reviewed and accepted by Lars Ingebrigtsen.

> I'm not sure I understand the purpose of the last sentence, nor what
> Symbols are easier to compare and harder to make mistakes.

This setting accepts a free-form write-in. There may be more Latex
environments satisfying the "tabular" protocol, not just "tabular"
itself and "longtable". I haven't done an extensive survey, but I
suspect that most do. If this value is interpreted as a symbol, it
would require a "symbol->string" at the time of actually writing
the code into the final buffer. I don't think that a symbol would
really fit here.

-- 
Your sincerely,
Vladimir Nikishkin (MiEr, lockywolf)
(Laptop)