#+Title: How to view the information present at a call line

This call line passes its in-buffer location to a code block.  Notice
that the call to =(point)= in the call line is saved into a header
argument named =:my-point= and is then retrieved by the variable
initialization.  This indirection is required because of /when/ and
/where/ the elisp forms in header arguments are evaluated, a simpler
call line like =#+call: show:((point))= would not work because the
form =(point)= would not be evaluated in the correct place.

#+call: show[:my-point (point)]((cdr (assoc :my-point (nth 2 info)))) :special-header "foo"

The special header argument =:special-header= may be seen in the
output below.  The =results= variable is due to the way that call
lines are evaluated.  During evaluation a call line is converted into
a trivial elisp code block of the form
: #+begin_src emacs-lisp :var results=called-function()
:   results
: #+end_src
which is evaluated in place.

#+RESULTS: show[:my-point (point)]((cdr (assoc :my-point (nth 2 info))))
| (:var results ((:var nil)) ((:colname-names)) ((:rowname-names)) ((:result-params replace)) ((:result-type . value)) ((:comments . )) ((:shebang . )) ((:cache . no)) ((:padline . )) ((:noweb . yes)) ((:tangle . no)) ((:exports . code)) ((:results . replace)) ((:padnewline . yes)) ((:hlines . no)) ((:session . none))) |
| (:colname-names)                                                                                                                                                                                                                                                                                                               |
| (:rowname-names)                                                                                                                                                                                                                                                                                                               |
| (:result-params replace)                                                                                                                                                                                                                                                                                                       |
| (:result-type . value)                                                                                                                                                                                                                                                                                                         |
| (:comments . )                                                                                                                                                                                                                                                                                                                 |
| (:shebang . )                                                                                                                                                                                                                                                                                                                  |
| (:cache . no)                                                                                                                                                                                                                                                                                                                  |
| (:padline . )                                                                                                                                                                                                                                                                                                                  |
| (:noweb . yes)                                                                                                                                                                                                                                                                                                                 |
| (:tangle . no)                                                                                                                                                                                                                                                                                                                 |
| (:exports . code)                                                                                                                                                                                                                                                                                                              |
| (:results . replace)                                                                                                                                                                                                                                                                                                           |
| (:special-header . foo)                                                                                                                                                                                                                                                                                                        |
| (:padnewline . yes)                                                                                                                                                                                                                                                                                                            |
| (:hlines . no)                                                                                                                                                                                                                                                                                                                 |
| (:session . none)                                                                                                                                                                                                                                                                                                              |

This code block visits the location of the call line, and calculates
the info using the same mechanisms used by =org-babel-lob-execute=.
#+name: show
#+begin_src emacs-lisp :var call-line-location=0
  (let ((call-info (save-excursion
                     (goto-char call-line-location)
                     (org-babel-lob-get-info))))
    (mapcar #'list
            (org-babel-process-params
             (org-babel-merge-params
              org-babel-default-header-args
              (org-babel-params-from-properties)
              (org-babel-parse-header-arguments
               (org-babel-clean-text-properties
                (concat ":var results="
                        (mapconcat #'identity (butlast call-info) " "))))))))
#+end_src