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From: Eric Schulte <schulte.eric@gmail.com>
To: Org Mode Mailing List <emacs-orgmode@gnu.org>
Subject: [RFC] new :post header argument for post-processing of code block results
Date: Sun, 31 Mar 2013 19:17:46 -0600	[thread overview]
Message-ID: <87bo9zoxqd.fsf@gmail.com> (raw)

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I've been wanting to add the ability to post-process the results of a
code block for some time, and some recent threads (e.g., [1] and [2])
could both have benefited from post-processing of code block output.

The attached patch [3] adds a new :post header argument, which may be
used to specify a code block reference to use to post-process the
results of the current code block.  The following example illustrates
how this header argument could be used to add attr_latex lines to table
code block results.

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#+Title: Proposed =post= Header Argument
#+Author: Eric Schulte

* a code block which does the post processing
This code block adds latex width attributes to whatever =data= is
passed to it.
#+name: add-attr
#+begin_src sh :var data="" :results output drawer :var width="\textwidth"
  echo "#+attr_latex: width=$width"
  echo "$data"

* two code blocks which use the post processing
The following two code blocks demonstrate the use of the new =post=
header argument, whcih we could add if it seems generally useful and
not too confusing.

This works by lexically binding the =*this*= variable to the results
of the current code block, and then calling the =add-attr= code block
to post-process these results.

#+begin_src sh :results output wrap :post add-attr(width="5cm",data=(identity *this*))
cat <<EOF
| 1 | 2 |
| 3 | 4 |

#+attr_latex: width=5cm
| 1 | 2 |
| 3 | 4 |

This code block does the same thing as the previous one, but using
different values and arguments.

#+header: :post add-attr(width="0.5\\textwidth",data=(identity *this*))
#+begin_src sh :results output wrap
cat <<EOF
| 5 | 6 |
| 7 | 8 |

#+attr_latex: width=0.5\textwidth
| 5 | 6 |
| 7 | 8 |

* another unrelated example
Say we only care about the size of our results, then we could use the
#+name: wc
#+begin_src sh data=""
  echo "$data"|wc

This code block checks the size of some Emacs Lisp data (in this case
my =load-path= variable).
#+begin_src emacs-lisp :post wc(data=(identity *this*))

: 160     160    6783

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Does this new header argument seem useful?  Any suggestions for better
syntax which don't add too much conceptual or code complexity?


[1]  http://thread.gmane.org/gmane.emacs.orgmode/69339

[2]  http://thread.gmane.org/gmane.emacs.orgmode/68700


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From f83f31d82c0c660c74a2af7114d4e23c9b37c095 Mon Sep 17 00:00:00 2001
From: Eric Schulte <schulte.eric@gmail.com>
Date: Sun, 31 Mar 2013 19:02:11 -0600
Subject: [PATCH] :post header arg post-processes code block results

* lisp/ob-core.el (org-babel-common-header-args-w-values): Add :post to
  the list of header arguments.
  (org-babel-execute-src-block): Post process results when the :post
  header argument has been supplied.
 lisp/ob-core.el | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/lisp/ob-core.el b/lisp/ob-core.el
index 723aa9d..e1321eb 100644
--- a/lisp/ob-core.el
+++ b/lisp/ob-core.el
@@ -456,6 +456,7 @@ then run `org-babel-pop-to-session'."
     (noweb-ref	. :any)
     (noweb-sep  . :any)
     (padline	. ((yes no)))
+    (post       . :any)
     (results	. ((file list vector table scalar verbatim)
 		   (raw html latex org code pp drawer)
 		   (replace silent none append prepend)
@@ -625,6 +626,11 @@ block."
 				      (not (listp result)))
 				 (list (list result)) result))
 			   (funcall cmd body params)))
+		    ;; possibly perform post process provided its appropriate
+		    (when (cdr (assoc :post params))
+		      (let ((*this* result))
+			(setq result (org-babel-ref-resolve
+				      (cdr (assoc :post params))))))
 		    ;; if non-empty result and :file then write to :file
 		    (when (cdr (assoc :file params))
 		      (when result

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Eric Schulte

             reply	other threads:[~2013-04-01  1:18 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-04-01  1:17 Eric Schulte [this message]
2013-04-01  5:30 ` [RFC] new :post header argument for post-processing of code block results Aaron Ecay
2013-04-03 14:30   ` Eric Schulte
2013-04-04  2:18     ` Eric Schulte
2013-04-04  9:54       ` Bastien
2013-04-04 12:47         ` Eric Schulte
2013-04-04 12:54           ` Bastien
2014-12-12 16:37     ` Christian Nybø
2013-04-16 12:47 ` Eric S Fraga
2013-04-16 15:23   ` Eric Schulte
2013-04-16 20:42     ` Andreas Leha

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