Re: Inserting tables programatically in elisp

[Jean Louis <bugs@gnu.support>]

* Heime <heimeborgia@protonmail.com> [2022-11-05 10:45]:
> Have been introspecting the possibility of conveniently inserting table programatically
> in elisp and encountered "table.el".
> 
> Have constructed this function, but the difficulty centers around
> the challenge of inserting text in specific tests.
> 
> (defun make-table ()
>   (interactive)
>   (table-insert 4 5)
>   (table-forward-cell)
>   (table-insert-sequence "icomplt-horz" 1 1 1 'center)
>   (table-forward-cell 4)
>   (table-insert-sequence "icomplt-vert" 1 1 1 'center)
>   (table-release))
> 
> It might be that "table.el" was designed under the assumption that the table would
> be edited interactively rather than from ELisp.  The lack of info may just reflect
> that nobody has thought about it making tables programatically that also goes beyond
> its utilisation in "org-mode".
> 
> I understand that "Org" cooperates with its author Takaaki Ota, perhaps things could
> be extended in a way that makes inserting tables programatically much easier to work
> with.

I would go programmatically not by hard coding the table walk, but by
using some structure, for example:

(setq my-table '(("ID" "Description" "Amount") ;; this must be header
		 (1 "Payment for domain" 10.50)
		 (2 "Transfer from Doe" 250)))

Then I would use some function, something like:

(my-org-table-generate my-table calculat-total 3rd-column)

Then the function would only interpolate the table with basic
 small details, which allow later automatic table alignment:

(defun rcd-org-table-cell (object)
  (cond ((numberp object) (format "| %.2f " object))
	(t (format "| %s " object))))

(rcd-org-table-cell "Hello") ⇒ "| Hello "

(defun rcd-org-table-horizontal-line ()
  "Return `|-' as horizontal-line."
  "|--\n")

then for rows:

(defun rcd-org-table-row (list)
  (with-temp-buffer
    (while list
      (insert (rcd-org-table-cell (pop list))))
    (insert "\n")
    (buffer-string)))

This means you can do something like:

(rcd-org-table-row '("ID" "Description" "Amount")) ⇒ "| ID | Description | Amount "

then you make the main function:

(defun rcd-org-table (structure)
  (let ((header (pop structure)))
    (with-temp-buffer
      (insert "\n")
      (insert (rcd-org-table-row header))
      (insert (rcd-org-table-horizontal-line))
      (while structure
	(insert (rcd-org-table-row (pop structure))))
      (insert "\n")
      (org-mode)
      (goto-char 2)
      (org-table-align)
      (buffer-substring-no-properties (point-min) (point-max)))))

And now the final result:

(rcd-org-table my-table) ⇒ "
|   ID | Description        | Amount |
|------+--------------------+--------|
| 1.00 | Payment for domain |  10.50 |
| 2.00 | Transfer from Doe  | 250.00 |

"


-- 
Jean

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