Re: org table proposal: merge and split cells in org-tables

[Max Nikulin <manikulin@gmail.com>]

I believe that tables in Org are already too complicated due to the 
spreadsheet feature. However those who are brave enough to add cells 
spanning columns and rows may take some inspiration from 
reStructuredText, in particular horizontal lines marked by "+===+===+"

https://docutils.sourceforge.io/docs/ref/rst/restructuredtext.html#tables
> Grid tables are described with a visual grid made up of the characters "-", "=", "|", and "+". The hyphen ("-") is used for horizontal lines (row separators). The equals sign ("=") may be used to separate optional header rows from the table body (not supported by the Emacs table mode). The vertical bar ("|") is used for vertical lines (column separators). The plus sign ("+") is used for intersections of horizontal and vertical lines. Example:
> 
> +------------------------+------------+----------+----------+
> | Header row, column 1   | Header 2   | Header 3 | Header 4 |
> | (header rows optional) |            |          |          |
> +========================+============+==========+==========+
> | body row 1, column 1   | column 2   | column 3 | column 4 |
> +------------------------+------------+----------+----------+
> | body row 2             | Cells may span columns.          |
> +------------------------+------------+---------------------+
> | body row 3             | Cells may  | - Table cells       |
> +------------------------+ span rows. | - contain           |
> | body row 4             |            | - body elements.    |
> +------------------------+------------+---------------------+

RST tables have a feature making hard to implement autoalignment. If 
come cell have "|" with offset in respect to lines above and below then
it is a regular character.

Besides "grid" tables there are "simple" tables without vertical lines.

Perhaps it better to implement new table features as src blocks for some 
new language and a dedicated Emacs mode. In the case of success such 
proof of concept may be merged into Org core.

My impression is that Org tables quickly become hardly maintainable when 
their complexity is above some quite low threshold. E.g. automatic 
recalculation works only for first #+tblfm: line. It requires some 
efforts to figure out association of particular formula with cell spans.

Merge cells add more complexity to formula ranges. Some protocol should 
be defined to allow source blocks to generate extended cells.