Re: [O] Injecting properties with noweb

[Ken Mankoff]

Hi Ihor,

I had posted this in another thread, but repeat it here for anyone interested. 
I think it is a similar end result to what you posted, but skips the =identity= 
 step. The examples below show (1) setting a bash environment variable in 
screen, or (2) printing from a Python prompt after sshing to a remote computer. 
It is language agnostic. Because it uses PROPERTIES and not :var, it also lets 
me work in Org Column View mode.


* Header
:PROPERTIES:
:foo: 42
:END:

#+NAME: ex1-screen-bash
#+BEGIN_SRC screen

export foo="<<get_property("foo")>>"
#+END_SRC

#+NAME: ex2-ssh-python
#+BEGIN_SRC bash

ssh somewhere
python
print("<<get_property("foo")>>")
#+END_SRC

#+CALL: ex2-ssh-python()

#+RESULTS:
: foo


The relevant section from my library-of-babel is:

* Properties into header args
:PROPERTIES:
:hellomessage: hello
:END:

https://emacs.stackexchange.com/questions/41922/

#+NAME: get_property
#+BEGIN_SRC emacs-lisp :var prop_name="" :results silent

(org-with-point-at org-babel-current-src-block-location
  (org-entry-get nil prop_name t))
#+END_SRC

** Example Usage

*** Header arg

#+HEADER: :var prop_message=(org-entry-get nil "hellomessage" t)
#+BEGIN_SRC emacs-lisp
  (message prop_message)
#+END_SRC

#+RESULTS:
: hello

*** Noweb

#+BEGIN_SRC emacs-lisp :noweb yes
  (message "<<get_property("hellomessage")>>")
#+END_SRC


#+RESULTS:
: hello

#+BEGIN_SRC bash :noweb yes :results verbatim
echo "<<get_property("hellomessage")>>"
#+END_SRC

#+RESULTS:
: hello

If hope this helps someone if they need it.

  -k.




On 2023-04-08 at 05:22 -07, Ihor Radchenko <yantar92@posteo.net> wrote...
> Ken Mankoff <mankoff@gmail.com> writes:
>
>> Is it possible to set variables using Org Babel inside screen, which
>> does not support ":var" header args? I'd actually lke a double-nested
>> screen over ssh, and the ability to re-use Babel code blocks under
>> different headings, using header args or PROPERTIES to change
>> variables. That is, something like:
>
> Yes.
>
>> ...
>> #+NAME: get-prop
>> #+BEGIN_SRC emacs-lisp :var prop="FOO" :noweb yes
>> (org-macro--get-property prop "")
>> #+END_SRC
>>
>> #+NAME: inject_vars
>> #+BEGIN_SRC shell :noweb yes
>> # echo <<get-prop(prop="FOO")>> # testing
>> echo export FOO=<<get-prop(prop="FOO")>>
>> echo export BAR=<<get-prop(prop="BAR")>>
>> echo export BAZ=<<get-prop(prop="BAZ")>>
>> #+END_SRC
>
> This did not work as you expected because noweb evaluates code block
> with point at that code block.
>
> To get the property value at the code block where you expand noweb
> reference, you need to compute the value in the arguments to the
> reference. Something like
>
> #+name: identity
> #+begin_src elisp :var x=""
>
> x
> #+end_src
>
> ...
> echo export FOO=<<identity(x=(org-macro--get-property prop "FOO"))
> ...