new exporter, conditional options according to backend

new exporter, conditional options according to backend

[Ezequiel Birman]

Is it possible to write something like this with the new exporter?

#+OPTIONS: (if (and (boundp 'org-export-current-backend) (eq org-export-current-backend 'e-beamer)) "H:1" "H:3")

From what I read in org-export.el the backend is stored in a plist, not
sure how to get it's value when exporting.

Or, maybe I need to write a filter function to be run from
org-export-before-process-hook?

-- 
Ezequiel Birman

Re: new exporter, conditional options according to backend

[Nicolas Goaziou]

Hello,

Ezequiel Birman <stormwatch@espiga4.com.ar> writes:

> Is it possible to write something like this with the new exporter?
>
> #+OPTIONS: (if (and (boundp 'org-export-current-backend) (eq org-export-current-backend 'e-beamer)) "H:1" "H:3")

There is no `org-export-current-backend' in the new exporter. Besides,
what you want is the default behaviour (see `org-e-beamer-frame-level'
variable).

> From what I read in org-export.el the backend is stored in a plist, not
> sure how to get it's value when exporting.
>
> Or, maybe I need to write a filter function to be run from
> org-export-before-process-hook?

Filters are different from hook. A function in a hook operates on an Org
buffer. A filter function operates either on a string in output syntax
or on the parse tree.

If, for some reason, you want to modify export options "on the fly", you
could create a filter function for parse tree, and modify options plist
from it:

#+begin_src emacs-lisp
(defun my-options-change-fun (tree backend info)
  (when (org-export-derived-backend-p backend 'e-beamer)
    (plist-put info :with-author nil))
  ;; Don't forget to return tree.
  tree)

(add-to-list 'org-export-filter-parse-tree-functions
             'my-options-change-fun)
#+end_src


Regards,

-- 
Nicolas Goaziou

Re: new exporter, conditional options according to backend

[Ezequiel Birman]

>>>>> "Nicolas" == Nicolas Goaziou <n.goaziou@gmail.com> writes:

    > Hello, Ezequiel Birman <stormwatch@espiga4.com.ar> writes:

    >> Is it possible to write something like this with the new
    >> exporter?
    >> 
    >> #+OPTIONS: (if (and (boundp 'org-export-current-backend) (eq
    >> org-export-current-backend 'e-beamer)) "H:1" "H:3")

    > There is no `org-export-current-backend' in the new
    > exporter. Besides, what you want is the default behaviour (see
    > `org-e-beamer-frame-level' variable).

    >> From what I read in org-export.el the backend is stored in a
    >> plist, not sure how to get it's value when exporting.
    >> 
    >> Or, maybe I need to write a filter function to be run from
    >> org-export-before-process-hook?

    > Filters are different from hook. A function in a hook operates on
    > an Org buffer. A filter function operates either on a string in
    > output syntax or on the parse tree.

    > If, for some reason, you want to modify export options "on the
    > fly", you could create a filter function for parse tree, and
    > modify options plist from it:

    > #+begin_src emacs-lisp (defun my-options-change-fun (tree backend
    > info) (when (org-export-derived-backend-p backend 'e-beamer)
    > (plist-put info :with-author nil)) ;; Don't forget to return tree.
    > tree)

    > (add-to-list 'org-export-filter-parse-tree-functions
    > 'my-options-change-fun) #+end_src


    > Regards,

    > -- Nicolas Goaziou

Thanks for the example and the clarificatons re filters versus hooks,
and for thinking of those sane defaults ahead too.

-- 
Ezequiel Birman

Re: new exporter, conditional options according to backend

[Jambunathan K]

Nicolas Goaziou <n.goaziou@gmail.com> writes:

> #+begin_src emacs-lisp
> (defun my-options-change-fun (tree backend info)
>   (when (org-export-derived-backend-p backend 'e-beamer)
>     (plist-put info :with-author nil))
>   ;; Don't forget to return tree.
>   tree)

CAVEAT: plist-put can return a different list, at times.

I don't know enough about implementation of `plist-put' to ascertain
when it would return a new list.

> (add-to-list 'org-export-filter-parse-tree-functions
>              'my-options-change-fun)

-- 

Re: new exporter, conditional options according to backend

[Nicolas Goaziou]

Jambunathan K <kjambunathan@gmail.com> writes:

> Nicolas Goaziou <n.goaziou@gmail.com> writes:
>
>> #+begin_src emacs-lisp
>> (defun my-options-change-fun (tree backend info)
>>   (when (org-export-derived-backend-p backend 'e-beamer)
>>     (plist-put info :with-author nil))
>>   ;; Don't forget to return tree.
>>   tree)
>
> CAVEAT: plist-put can return a different list, at times.
>
> I don't know enough about implementation of `plist-put' to ascertain
> when it would return a new list.

Since the OP wants to modify the values of _existing properties_ I'm
quite sure the change will happen in place.


Regards,

-- 
Nicolas Goaziou

Re: new exporter, conditional options according to backend

[Jambunathan K]

Nicolas Goaziou <n.goaziou@gmail.com> writes:

> Jambunathan K <kjambunathan@gmail.com> writes:
>
>> Nicolas Goaziou <n.goaziou@gmail.com> writes:
>>
>>> #+begin_src emacs-lisp
>>> (defun my-options-change-fun (tree backend info)
>>>   (when (org-export-derived-backend-p backend 'e-beamer)
>>>     (plist-put info :with-author nil))
>>>   ;; Don't forget to return tree.
>>>   tree)
>>
>> CAVEAT: plist-put can return a different list, at times.
>>
>> I don't know enough about implementation of `plist-put' to ascertain
>> when it would return a new list.
>
> Since the OP wants to modify the values of _existing properties_ I'm
> quite sure the change will happen in place.

Look at example in Elisp manual.  New members seem to get appended.  

List being destructive is explainable if new members were to be added to
the head.  Since this is not the case, I am curious what the
implementation could be ...


>
>
> Regards,

-- 

Re: new exporter, conditional options according to backend

[Nicolas Goaziou]

Hello,

Jambunathan K <kjambunathan@gmail.com> writes:

> Nicolas Goaziou <n.goaziou@gmail.com> writes:
>
>> Jambunathan K <kjambunathan@gmail.com> writes:
>>
>>> Nicolas Goaziou <n.goaziou@gmail.com> writes:
>>>
>>>> #+begin_src emacs-lisp
>>>> (defun my-options-change-fun (tree backend info)
>>>>   (when (org-export-derived-backend-p backend 'e-beamer)
>>>>     (plist-put info :with-author nil))
>>>>   ;; Don't forget to return tree.
>>>>   tree)
>>>
>>> CAVEAT: plist-put can return a different list, at times.
>>>
>>> I don't know enough about implementation of `plist-put' to ascertain
>>> when it would return a new list.
>>
>> Since the OP wants to modify the values of _existing properties_ I'm
>> quite sure the change will happen in place.
>
> Look at example in Elisp manual.  New members seem to get appended.  
>
> List being destructive is explainable if new members were to be added to
> the head.  Since this is not the case, I am curious what the
> implementation could be ...

I have added a filter for export options. The OP may want to use it
instead.

I guess it will be cleaner that way. Besides, the previous export
framework had one too.


Regards,

-- 
Nicolas Goaziou

Re: new exporter, conditional options according to backend

[Andreas Leha]

Hi Nicolas,

Nicolas Goaziou <n.goaziou@gmail.com> writes:

> Hello,
>
> Ezequiel Birman <stormwatch@espiga4.com.ar> writes:
>
>> Is it possible to write something like this with the new exporter?
>>
>> #+OPTIONS: (if (and (boundp 'org-export-current-backend) (eq org-export-current-backend 'e-beamer)) "H:1" "H:3")
>
> There is no `org-export-current-backend' in the new exporter. Besides,
> what you want is the default behaviour (see `org-e-beamer-frame-level'
> variable).
>
>> From what I read in org-export.el the backend is stored in a plist, not
>> sure how to get it's value when exporting.
>>
>> Or, maybe I need to write a filter function to be run from
>> org-export-before-process-hook?
>
> Filters are different from hook. A function in a hook operates on an Org
> buffer. A filter function operates either on a string in output syntax
> or on the parse tree.
>
> If, for some reason, you want to modify export options "on the fly", you
> could create a filter function for parse tree, and modify options plist
> from it:
>
> #+begin_src emacs-lisp
> (defun my-options-change-fun (tree backend info)
>   (when (org-export-derived-backend-p backend 'e-beamer)
>     (plist-put info :with-author nil))
>   ;; Don't forget to return tree.
>   tree)
>
> (add-to-list 'org-export-filter-parse-tree-functions
>              'my-options-change-fun)
> #+end_src
>
>
> Regards,

Sorry for hijacking this thread.  But I am also interested in backend
specific options.  Could you give an example of how to achieve something
like this with the new exporter:

#+begin_src R :results graphics :file (if (and (boundp 'org-export-current-backend) (eq org-export-current-backend 'e-latex)) "foo.pdf" "foo.png")
  plot(1:10)
#+end_src

Thanks in advance,
Andreas

Re: new exporter, conditional options according to backend

[Nicolas Goaziou]

Hello,

Andreas Leha <andreas.leha@med.uni-goettingen.de> writes:

> Sorry for hijacking this thread.  But I am also interested in backend
> specific options.  Could you give an example of how to achieve something
> like this with the new exporter:
>
> #+begin_src R :results graphics :file (if (and (boundp 'org-export-current-backend) (eq org-export-current-backend 'e-latex)) "foo.pdf" "foo.png")
>   plot(1:10)
> #+end_src

You need to process the buffer being exported before Babel blocks are
expanded. You could use `org-export-before-processing-hook' for that.

For example, you could define a specific extension for :file values,
like "foo.xxx", process the buffer and and replace "xxx" with an
appropriate extension according to the current back-end (the argument of
the function).


Regards,

-- 
Nicolas Goaziou

Re: new exporter, conditional options according to backend

[cberry]

Nicolas Goaziou <n.goaziou@gmail.com> writes:

> Hello,
>
> Ezequiel Birman <stormwatch@espiga4.com.ar> writes:
>
>> Is it possible to write something like this with the new exporter?
>>
>> #+OPTIONS: (if (and (boundp 'org-export-current-backend) (eq org-export-current-backend 'e-beamer)) "H:1" "H:3")
>
> There is no `org-export-current-backend' in the new exporter. Besides,
> what you want is the default behaviour (see `org-e-beamer-frame-level'
> variable).

'backend' is in the scope of transcoding functions like
inline-src-block.

I am currently taking advantage of this, but it is a shortcut rather
than a necessity. 

Is your advice "Don't do that" ?

Chuck
>
>> From what I read in org-export.el the backend is stored in a plist, not
>> sure how to get it's value when exporting.
>>
>> Or, maybe I need to write a filter function to be run from
>> org-export-before-process-hook?
>
> Filters are different from hook. A function in a hook operates on an Org
> buffer. A filter function operates either on a string in output syntax
> or on the parse tree.
>
> If, for some reason, you want to modify export options "on the fly", you
> could create a filter function for parse tree, and modify options plist
> from it:
>
> #+begin_src emacs-lisp
> (defun my-options-change-fun (tree backend info)
>   (when (org-export-derived-backend-p backend 'e-beamer)
>     (plist-put info :with-author nil))
>   ;; Don't forget to return tree.
>   tree)
>
> (add-to-list 'org-export-filter-parse-tree-functions
>              'my-options-change-fun)
> #+end_src
>
>
> Regards,

Re: new exporter, conditional options according to backend

[Nicolas Goaziou]

Hello,

cberry@tajo.ucsd.edu writes:

> 'backend' is in the scope of transcoding functions like
> inline-src-block.
>
> I am currently taking advantage of this, but it is a shortcut rather
> than a necessity. 
>
> Is your advice "Don't do that" ?

I would rather say "Don't do that in public code". There's no guarantee
this hack will always work.

As you probably know, the clean way to retrieve the back-end symbol from
a transcoding function is:

  (plist-get info :back-end)

INFO being the third argument passed to the function.


Regards,

-- 
Nicolas Goaziou