From mboxrd@z Thu Jan  1 00:00:00 1970
From: tsd@tsdye.com (Thomas S. Dye)
Subject: Re: graphviz dot block export and evaluate
Date: Fri, 28 Sep 2012 07:14:15 -1000
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In-Reply-To: <C62ACE57-E48C-4F93-B585-CC75BE6363C7@gmail.com> (Dmitri
	Makarov's message of "Fri, 28 Sep 2012 18:51:56 +0200")
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To: Dmitri Makarov <dmakarv@gmail.com>
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Dmitri Makarov <dmakarv@gmail.com> writes:

> Hi all,
>
> Has anyone successfully exported and evaluated src blocks with
> graphviz dot code?
> I'm trying to export this block
>
>    #+BEGIN_SRC dot :export both
>      digraph G {
>        A -> B
>      }
>    #+END_SRC
>
> and I'm getting the error
>
> org-babel-exp processing...
> executing Dot code block...
> file-name-extension: Wrong type argument: stringp, nil
>
> How do you debug such problems?
>
> Regards,
>
> Dmitri

Aloha Dmitri,

Currently, you can debug such problems by looking at the source code of
ob-dot.el.  Or, by asking the list, as you did.

Your example is lacking a :file header argument.  dot source code blocks
produce graphics files and babel leaves it to the user to name the
output file.  The file-name-extension function is looking for the value
of the :file header argument, so that it can configure the call to dot.
It is expecting to see a string, but gets nil because the header
argument is absent.

Also, the correct keyword is :exports, with a final "s".

You can find an example of dot code use here:
http://www.jstatsoft.org/v46/i03

hth,
Tom
-- 
Thomas S. Dye
http://www.tsdye.com