Re: [PATCH] A proposal to add LaTeX attributes to verse blocks

[TEC <tecosaur@gmail.com>]

Hi Juan,

Thanks for your patch. 

This looks like a fairly sensible addition. Two comments from me:

1. I'm not sure that "options" is a good name for arbitrary LaTeX which
   is included inside the verse block. Perhaps something like "insert"
   or "include", etc. may be a better fit.
2. It's considered generally nice to document features like this :) The
   two documents which I'd think to note this in are ORG-NEWS and the
   manual (docs/manual.org).

All the best,

Timothy.

Juan Manuel Macías <maciaschain@posteo.net> writes:

> (Sorry, due to a mistake, the text of my message did not appear in my previous email)
>
> Hi,
>
> I would like to propose this patch to add some LaTeX attributes to the verse block,
> especially to be able to apply certain features from the verse.sty package, which is an
> extension (widely used in Humanities) of the standard LaTeX 'verse' environment.
>
> These attributes would be:
>
> - `:lines' to add verse numbers, according to any numbering sequence
> - `:center' to apply the optical centering of the poem, which is a typographic convention
>   whereby a poem or a group of verses is centered on the page, taking the width of the
>   longest verse as a reference. In fact, optical centering is the correct arrangement of
>   verses in a document.
> - `:versewidth' which expects a text string that is the longest verse of the poem,
>   required when applying the `:center' attribute.
>
> As I said, these three attributes require the LateX package verse.sty. A fourth `:options'
> attribute would be used to add arbitrary code within the verse environment.
>
> Consider this complete example with Shakespeare's first sonnet:
>
> #+begin_src org
>   ,#+ATTR_LaTeX: :center t :options \small :lines 5
>   ,#+ATTR_LaTeX: :versewidth Feed’st thy light’st flame with self-substantial fuel,
>   ,#+begin_verse
>   From fairest creatures we desire increase,
>   That thereby beauty’s rose might never die,
>   But as the riper should by time decrease,
>   His tender heir mught bear his memeory:
>   But thou, contracted to thine own bright eyes,
>   Feed’st thy light’st flame with self-substantial fuel,
>   Making a famine where abundance lies,
>   Thyself thy foe, to thy sweet self too cruel.
>   Thou that art now the world’s fresh ornament
>   And only herald to the gaudy spring,
>   Within thine own bud buriest thy content
>   And, tender churl, makest waste in niggarding.
>   Pity the world, or else this glutton be,
>   To eat the world’s due, by the grave and thee.
>   ,#+end_verse
> #+end_src
>
> when exporting to LaTeX we get:
>
> #+begin_src latex
> \settowidth{\versewidth}{Feed’st thy light’st flame with self-substantial fuel,}
> \begin{verse}[\versewidth]
> \poemlines{5}
> \small
> From fairest creatures we desire increase,\\
> That thereby beauty’s rose might never die,\\
> But as the riper should by time decrease,\\
> His tender heir mught bear his memeory:\\
> But thou, contracted to thine own bright eyes,\\
> Feed’st thy light’st flame with self-substantial fuel,\\
> Making a famine where abundance lies,\\
> Thyself thy foe, to thy sweet self too cruel.\\
> Thou that art now the world’s fresh ornament\\
> And only herald to the gaudy spring,\\
> Within thine own bud buriest thy content\\
> And, tender churl, makest waste in niggarding.\\
> Pity the world, or else this glutton be,\\
> To eat the world’s due, by the grave and thee.\\
> \end{verse}
> #+end_src
>
> In an attached image I send a screenshot with the typographic result
>
> And finally, this is the patch I would propose
>
> #+begin_src diff
> diff --git a/lisp/ox-latex.el b/lisp/ox-latex.el
> index 2a14b25d5..bc6b64e78 100644
> --- a/lisp/ox-latex.el
> +++ b/lisp/ox-latex.el
> @@ -3506,6 +3506,16 @@ channel."
>    "Transcode a VERSE-BLOCK element from Org to LaTeX.
>  CONTENTS is verse block contents.  INFO is a plist holding
>  contextual information."
> +(let*
> +      ((lin (org-export-read-attribute :attr_latex verse-block :lines))
> +       (opt (org-export-read-attribute :attr_latex verse-block :options))
> +       (cent (org-export-read-attribute :attr_latex verse-block :center))
> +       (attr (concat
> +	      (if cent "[\\versewidth]" "")
> +	      (if lin (format "\n\\poemlines{%s}" lin) "")
> +	      (if opt (format "\n%s" opt) "")))
> +       (versewidth (org-export-read-attribute :attr_latex verse-block :versewidth))
> +       (vwidth-attr (if versewidth (format "\\settowidth{\\versewidth}{%s}\n" versewidth) "")))
>    (concat
>     (org-latex--wrap-label
>      verse-block
> @@ -3513,7 +3523,9 @@ contextual information."
>      ;; character and change each white space at beginning of a line
>      ;; into a space of 1 em.  Also change each blank line with
>      ;; a vertical space of 1 em.
> -    (format "\\begin{verse}\n%s\\end{verse}"
> +    (format "%s\\begin{verse}%s\n%s\\end{verse}"
> +	      vwidth-attr
> +	      attr
> 	    (replace-regexp-in-string
> 	     "^[ \t]+" (lambda (m) (format "\\hspace*{%dem}" (length m)))
> 	     (replace-regexp-in-string
> @@ -3524,7 +3536,7 @@ contextual information."
>      info)
>     ;; Insert footnote definitions, if any, after the environment, so
>     ;; the special formatting above is not applied to them.
> -   (org-latex--delayed-footnotes-definitions verse-block info)))
> +   (org-latex--delayed-footnotes-definitions verse-block info))))
> #+end_src
>
> Regards,
>
> Juan Manuel