Turn on noweb references for all org buffers

Question

I want to use the noweb style references in Emacs org for literate programming.

Consider the following working code.

#+NAME:Header
#+BEGIN_SRC c++
#include <iostream>
#+END_SRC


Blah blah


#+BEGIN_SRC c++ :tangle test.cpp :noweb yes
<<Header>>
int main (void)
{
   std::cout << "Hello World" << std::endl;
}
#+END_SRC

I don't want to have to specify :noweb yes every time to expand noweb references since I will always be expanding them by default. How do I change my .emacs file to tell org mode this?

Answer 1

There's an example for doing just what you are asking in the Org Manual:

https://orgmode.org/manual/System_002dwide-header-arguments.html#System_002dwide-header-arguments

Here it is for convenience:

This example sets :noweb header arguments to yes, which makes Org expand :noweb references by default.

 (setq org-babel-default-header-args
      (cons '(:noweb . "yes")
            (assq-delete-all :noweb org-babel-default-header-args)))

Answer 2

you can either set a global property on the top of the org file:

#+PROPERTY: header-args :noweb yes

or you can set a "tree node" property at any node level that is a parent of your src block:

* Parent Node
 :PROPERTIES:
 :header-args: :noweb yes
 :END:

Big warning: if you will want to add more of such properties either add them on the same line:

#+PROPERTY: header-args :noweb yes :result output

* Parent Node
 :PROPERTIES:
 :header-args: :noweb yes :result output
 :END:

or use concatenation to accumulate your values (otherwise your property value will equal to the last entry:

#+PROPERTY: header-args :noweb yes 
#+PROPERTY: header-args+ :result output

* Parent Node
 :PROPERTIES:
 :header-args: :noweb yes 
 :header-args+: :result output
 :END:

Notice the use of + sign in order to concatenate and not overwrite

Answer 3

Try setq org-babel-default-header-args.