From mboxrd@z Thu Jan 1 00:00:00 1970 From: D M German Subject: evaluation of perl in babel Date: Sun, 24 Feb 2013 13:08:39 -0800 Message-ID: <87hal1whbc.fsf@mn.cs.uvic.ca> Reply-To: dmg@uvic.ca Mime-Version: 1.0 Content-Type: text/plain Return-path: Received: from eggs.gnu.org ([208.118.235.92]:36978) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1U9ioV-0008MD-BI for emacs-orgmode@gnu.org; Sun, 24 Feb 2013 16:08:55 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1U9ioO-0007qb-Iy for emacs-orgmode@gnu.org; Sun, 24 Feb 2013 16:08:51 -0500 Received: from mail-pb0-f45.google.com ([209.85.160.45]:58026) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1U9ioO-0007qW-D4 for emacs-orgmode@gnu.org; Sun, 24 Feb 2013 16:08:44 -0500 Received: by mail-pb0-f45.google.com with SMTP id ro8so1296995pbb.18 for ; Sun, 24 Feb 2013 13:08:43 -0800 (PST) List-Id: "General discussions about Org-mode." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-orgmode-bounces+geo-emacs-orgmode=m.gmane.org@gnu.org Sender: emacs-orgmode-bounces+geo-emacs-orgmode=m.gmane.org@gnu.org To: emacs-orgmode@gnu.org Hi Everybody, I looked a bit more onto the way that perl is evaluated. I know the support of perl is minor. I understand that, so please, don't see this message as a complaint, so this is more for discussion and potential improvements of the Perl support in Babel. One of the things I have noticed is that the way that Babel handles the results coming from the code is not the best. Let me elaborate: At the bottom you will find a set of test that stress the different :results types. There are some bugs. For example, the interpretation of :results table, vector and list. But I think the main problem comes from the way that Babel expects the result. In Babel, and except for :results output, the last expression in perl is considered the input to the results. This is implementing by saving the last expression into a variable, and printing each value separated by a "\n" (including the last). So basically, org takes the last expression, and outputs them to the babel input file one per line. This places some constraints. First, it is not currently capable of dealing with two dimensional arrays. Second, it makes it hard to create complex output (such as HTML or LaTeX), and third, it is hard to debug without first printing the value of the array (this output would be lost during the evaluation, so it would have be debugged outside org). I feel that a better approach is to use std output as the default input to any of these :results types, and then try to parse them into the corresponding :results types. This will allow the creation of HTML and LaTeX from perl (which the current implementation does not allow). So recapitulating, my suggestion is that perl should use STDOUT as the output of the snippet in any :results type, rather than the result of the last expression. I know this will break backwards compatibility. One solution is to keep the current src perl and add a new perl_stdout mode (or something like that) that implements this. --dmg ---------------------------------------------------------------------- #+begin_src perl :results output print "Test\n"; (1, 2) #+end_src #+RESULTS: : Test #+name: t_output_raw #+begin_src perl :results raw print "Test\n"; (1, 2) #+end_src #+RESULTS: t_output_raw 1 2 #+name: t_output_table #+begin_src perl :results table print "Test\n"; (1, 2) #+end_src #+RESULTS: t_output_table | 1\n2\n | #+name: t_output_vector #+begin_src perl :results vector print "Test\n"; (1, 2) #+end_src #+RESULTS: t_output_vector | 1\n2\n | #+name: t_output_list #+begin_src perl :results list print "Test\n"; (1, 2) #+end_src #+RESULTS: t_output_list #+begin_example - 1 2 #+end_example #+name: t_output_org #+begin_src perl :results org print "Test\n"; (1, 2) #+end_src #+RESULTS: t_output_org #+BEGIN_SRC org 1 2 #+END_SRC #+name: t_output_html #+begin_src perl :results html print "Test\n"; (1, 2) #+end_src #+RESULTS: t_output_html #+BEGIN_HTML 1 2 #+END_HTML #+name: t_output_latex #+begin_src perl :results latex print "Test\n"; (1, 2) #+end_src #+RESULTS: t_output_latex #+BEGIN_LaTeX 1 2 #+END_LaTeX ---------------------------------------------------------------------- -- Daniel M. German "I see no good reason why the views given in this volume should shock the religious Charles Darwin -> feelings of anyone." http://turingmachine.org/ http://silvernegative.com/ dmg (at) uvic (dot) ca replace (at) with @ and (dot) with .