I get error "reference y not found in this buffer" when trying to evaluate cubed-plus-cubed:

#+NAME: cubed
#+BEGIN_SRC python :var x=3
return x * x * x

#+RESULTS: cubed
: 27

#+NAME: cubed-plus-cubed
#+BEGIN_SRC python :var y=0 :noweb eval
<<cubed(x=y)>> + <<cubed(x=y)>>

Why does not it work?

I also imagine my philosophy here could be all wrong and all this is done very differently in practice.

1 Answer 1


Try this

The reason why the error happens is because you haven't defined y in the x=y arguments.

If you update code as follows noweb will work

#+NAME: cubed-plus-cubed
#+BEGIN_SRC python :noweb eval
return <<cubed(x=3)>> + <<cubed(x=3)>>

#+RESULTS: cubed-plus-cubed
: 54

However I suspect this is not what you wanted because originally you added :var y=0

Another way to pass the value of variable x is to update your code as follows:

example 1

#+NAME: cubed-ex1
#+BEGIN_SRC python :var x=3 :session
  x * x * x

#+RESULTS: cubed-ex1
: 27

#+NAME: cubed-plus-cubed-ex1
#+BEGIN_SRC python :var x=3 :noweb eval :session
  <<cubed-ex1>> + <<cubed-ex1>>

#+RESULTS: cubed-plus-cubed-ex1
: 54

example 2

Add named example with value, e.g. x-ex2

#+NAME: x-ex2
: 3 

Pass named value to noweb

#+NAME: cubed-plus-cubed-ex2
#+BEGIN_SRC python :noweb eval
  return <<cubed(x=x-ex2())>> + <<cubed(x=x-ex2())>>

#+RESULTS: cubed-plus-cubed-ex2
: 54

Hope that helped!

This code was tested using
emacs version: GNU Emacs 25.2.1 (x86_64-unknown-cygwin, GTK+ Version 3.22.10)
org-mode version: Org mode version 9.1.2

  • So, I understand then. :var y is converted to the python's y inside the code block and so there would be a need to convert it back to an s-expression and that's not supported... In principle though, it does not need to be converted at all, the :var y could be passed unchanged in <<cubed(x=y)>>. But your examples do help! Thank you! Jan 10, 2018 at 20:40
  • @user3496846 - I think the reason <<cubed(x=y)>> didn't work is because noweb is evaluated and rendered before y was defined inside python which is why needed to move y declaration outside of python code block. Unfortunately, I can't find the order of operations in the org manual from which I learned this tidbit. Another way to workaround this issue to explicitly render the noweb recursively in multiple steps but it can be painfully convoluted. Another less painful way is to add #+NAME: above #+RESULTS:. I'll see if I can get a new example of rename solution and update my answer.
    – Melioratus
    Jan 10, 2018 at 21:13

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