accessing source block header arguments from exporters

accessing source block header arguments from exporters

[Robert Klein]

Hi,

is there a way, to read header arguments to source blocks in the
exporters org-<exporter>-src-block funktions?

E.g. is there a way to access :firstline in the example below?

#+begin_src c++ -n :firstline 23
   static struct
  {
      char                        *entity;
      unsigned char       equiv;
  } entities[] =
    {
      { "lt",           '<' } ,
      { "gt",           '>' } ,
      { "amp",          '&' } ,
      { "quot",         '"' } ,
      { "trade",        153 } , /* trade mark */
#+end_src

I didn't find it in the `element' structure.

However, if I use

#+begin_src c++ firstline=23
  // random C++
#+end_src

I could access :parameters from `element' and parse the string.
However I'm not sure if I'd break some babel stuff or not.

If I'm trying to implement a firstline feature -- source blocks with
new line numbering (-n) beginning at a given line number -- I'd prefer
to use :firstline, but I didn't find anything to suggest `:XXX ZZ'
header arguments to source blocks are available to the exporters.

Any advice?

Thank you very much
Robert

Re: accessing source block header arguments from exporters

[Charles Berry]

Robert Klein <roklein <at> roklein.de> writes:

> 
> Hi,
> 
> is there a way, to read header arguments to source blocks in the
> exporters org-<exporter>-src-block funktions?

Not directly. org-babel-exp-code has no provision for headers. 
They get dropped.

>
> E.g. is there a way to access :firstline in the example below?
> 

Not exactly, but ...

If you precede the code block with

#+attr_firstline: 23 

then with point in the src block

(org-element-property :attr_firstline (org-element-context))

will return ("23"). And org-*-src-block functions can use it.

If you really want to use the :firstline idiom, you can add a hook in 
`org-export-before-processing-hook' to find :firstline headers and 
insert #+attr_firstline lines in the buffer copy that the exporter is using.

> #+begin_src c++ -n :firstline 23
>    static struct
>   {
>       char                        *entity;
>       unsigned char       equiv;
>   } entities[] =
>     {
>       { "lt",           '<' } ,
>       { "gt",           '>' } ,
>       { "amp",          '&' } ,
>       { "quot",         '"' } ,
>       { "trade",        153 } , /* trade mark */
> #+end_src
> 
> I didn't find it in the `element' structure.
> 
> However, if I use
> 
> #+begin_src c++ firstline=23
>   // random C++
> #+end_src
> 
> I could access :parameters from `element' and parse the string.
> However I'm not sure if I'd break some babel stuff or not.
>

C-c C-v C-i on that src block shows that 'firstline=23' is treated as 
a switch by babel. So if there is any language that tries to use that 
as a switch (or has a regexp that matches it), there could be trouble.  
 
But in C it looks innocuous.

> If I'm trying to implement a firstline feature -- source blocks with
> new line numbering (-n) beginning at a given line number -- I'd prefer
> to use :firstline, but I didn't find anything to suggest `:XXX ZZ'
> header arguments to source blocks are available to the exporters.
> 

HTH,

Chuck

Re: accessing source block header arguments from exporters

[John Kitchin]

I agree with "Not exactly". In this post
http://kitchingroup.cheme.cmu.edu/blog/2014/09/22/Showing-what-data-went-into-a-code-block-on-export/
I did  something where I wanted to get information about the variables
passed into a block and show that on export. You might get some
inspiration from that. The result is at
http://kitchingroup.cheme.cmu.edu/media/2014-09-22-Showing-what-data-went-into-a-code-block-on-export/custom-src-table-export-3.html



Charles Berry writes:

> Robert Klein <roklein <at> roklein.de> writes:
>
>>
>> Hi,
>>
>> is there a way, to read header arguments to source blocks in the
>> exporters org-<exporter>-src-block funktions?
>
> Not directly. org-babel-exp-code has no provision for headers.
> They get dropped.
>
>>
>> E.g. is there a way to access :firstline in the example below?
>>
>
> Not exactly, but ...
>
> If you precede the code block with
>
> #+attr_firstline: 23
>
> then with point in the src block
>
> (org-element-property :attr_firstline (org-element-context))
>
> will return ("23"). And org-*-src-block functions can use it.
>
> If you really want to use the :firstline idiom, you can add a hook in
> `org-export-before-processing-hook' to find :firstline headers and
> insert #+attr_firstline lines in the buffer copy that the exporter is using.
>
>> #+begin_src c++ -n :firstline 23
>>    static struct
>>   {
>>       char                        *entity;
>>       unsigned char       equiv;
>>   } entities[] =
>>     {
>>       { "lt",           '<' } ,
>>       { "gt",           '>' } ,
>>       { "amp",          '&' } ,
>>       { "quot",         '"' } ,
>>       { "trade",        153 } , /* trade mark */
>> #+end_src
>>
>> I didn't find it in the `element' structure.
>>
>> However, if I use
>>
>> #+begin_src c++ firstline=23
>>   // random C++
>> #+end_src
>>
>> I could access :parameters from `element' and parse the string.
>> However I'm not sure if I'd break some babel stuff or not.
>>
>
> C-c C-v C-i on that src block shows that 'firstline=23' is treated as
> a switch by babel. So if there is any language that tries to use that
> as a switch (or has a regexp that matches it), there could be trouble.
>
> But in C it looks innocuous.
>
>> If I'm trying to implement a firstline feature -- source blocks with
>> new line numbering (-n) beginning at a given line number -- I'd prefer
>> to use :firstline, but I didn't find anything to suggest `:XXX ZZ'
>> header arguments to source blocks are available to the exporters.
>>
>
> HTH,
>
> Chuck

--
Professor John Kitchin
Doherty Hall A207F
Department of Chemical Engineering
Carnegie Mellon University
Pittsburgh, PA 15213
412-268-7803
@johnkitchin
http://kitchingroup.cheme.cmu.edu