How to programmatically update a named org-table in-situ

Question

It's possible to programmatically update an org table inside a babel source code block like the following:

#+name: mytable
| 0 | 0 | 0 |
| 0 | 0 | 0 |

#+begin_src emacs-lisp :var table=mytable
  (append table '((1 2 3)))
#+end_src

#+RESULTS:
| 0 | 0 | 0 |
| 0 | 0 | 0 |
| 1 | 2 | 3 |

I would like to update the original named table and discard the RESULTS output. In the case of this code it would keep appending a row to the table each time the source block is evaluated.

I've seen org samples that name the babel source the same as the source/target table (that presumably will do this) (https://eschulte.github.io/org-scraps/scraps/2011-08-19-replacing-a-table.html), but I get an org-get-property-block: Variable binding depth exceeds max-specpdl-size error whenever the names collide.

Answer 1

You can achieve that by naming your results table. Then, the code block will update the same table it used as input.

#+begin_src emacs-lisp :var table=mytable
  (append table '((1 2 3)))
#+end_src

#+name: mytable
#+RESULTS:
| 0 | 0 | 0 |
| 0 | 0 | 0 |
| 1 | 2 | 3 |

To have the greater flexibility that the OP had in mind: it isn't necessary to have the results immediately follow the source block if the source block and RESULTS label also share a name. Shown here:

#+name: mytable
#+RESULTS: mytable-calc
| 0 | 0 | 0 |
| 0 | 0 | 0 |
| 1 | 2 | 3 |

#+name: mytable-calc
#+begin_src emacs-lisp :var table=mytable
  (append table '((1 2 3)))
#+end_src

Answer 2

Having taken a look through the source, I'm not sure why that example would be expected to work. Perhaps org-babel has simply changed in the last four years.

Your test file works exactly as expected. Org-babel sees the table reference, calls into org-table to copy the table values from the buffer into a list structure, then passes that in as the argument. Your call to append copies the list, tacks on a new row and returns it. Org-babel formats the returned list structure as an org table.

What you'll probably have to do is pass in a string containing the name of the table (var="mytable"), find that named item (org-babel-named-data-regexp-for-name, I think?), narrow to it, double-check that it's a table and not something else (org-at-table-p), append the new row to it and widen again.