3

I have an interesting problem that I am sure there must be a simple answer to if I can find the right syntax.

Essentially, as outlined below, I have a simple sh code block that prints a variable that is declared as part of #+begin_src.

#+name: test-fn
#+begin_src sh :var testvar="This is a test"
echo testvar=$testvar
#+end_src

#+RESULTS: test-fn
: testvar=This is a test

#+begin_src sh :noweb yes
<<test-fn>>
#+end_src

#+RESULTS:
: testvar=

When I execute the code block directly, the parameter is evaluated. When it is called from a noweb reference in a different code block, the parameter is not evaluated.

How can I get the called code block to evaluate it's parameters?

EDIT1: I am using GNU Emacs 25.0.94.2 (x86_64-w64-mingw32) of 2016-05-26 running on Windows 10

EDIT2: Including the actual problem in detail 

#+name: test-harness-running?
#+begin_src ruby :results value
...
#+end_src

#+name: start-fw-test-harness
#+begin_src sh :noweb yes :var running=test-harness-running? :results output
...
#+end_src

#+name: remove-fw-flash
#+begin_src sh :results output
...
#+end_src

#+name: stop-fw-test-harness-if-running
#+begin_src sh :var running=test-harness-running? :noweb yes :results output
...
#+end_src

#+begin_src sh :noweb yes :results output
    <<stop-fw-test-harness-if-running>>
    <<remove-fw-flash>>
    <<start-fw-test-harness>>
#+end_src

The reason I've been doing it like this is I re-use stop-fw-test-harness-if-running, remove-fw-flash and start-fw-test-harness in many different scenarios (I used to use command line for it but I find babel gives me greater flexibility).

The problem is that start-fw-test-harness and stop-fw-test harness should only do their thing if the test harness is already started/stopped. However when called from a noweb reference, "running" never gets set as test-harness-running? is not called and so neither of these ever do anything. They work just fine when called directly.

EDIT3: Applying mutbuerger's solution to my problem, I get:

#+begin_src sh :noweb yes :results output :var dummy1=stop-fw-test-harness-if-running :var dummy2=remove-fw-flash :var dummy3=start-fw-test-harness
    echo $dummy1
    echo $dummy2
    echo $dummy3 
#+end_src

#+RESULTS:
: nil
: 22 Sep 2016 09:50:30 Deleting 351277001993561_STORE.prps 351277001993561_STORE.prps has been deleted
: nil

While this clearly works, I am reluctant to Accept the answer on account of the copious use of dummy variables and that I am not 100% sure the order in which the functions are called is clearly defined.

EDIT4:

Following mutbuerger's revised solution, this fixes my problem perfectly:

#+begin_src sh :results output :noweb yes
    <<stop-fw-test-harness-if-running()>>
    <<remove-fw-flash()>>
    <<start-fw-test-harness()>>
#+end_src
Matt Innes
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1 Answers1

4

There may be other solutions, this is how I would do it:

#+begin_src sh :noweb yes :var res=test-fn()
echo $res
#+end_src

#+results:
: testvar=This is a test

The same can be done without introducing the dummy variable (as is described in the documentation):

#+begin_src sh :noweb yes
echo <<test-fn()>>
#+end_src

#+results:
: testvar=This is a test
mutbuerger
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  • Yes, thanks for the feedback mutbuerger, that works. However I've really dumbed down my problem to keep it simple - the reason I am using a noweb reference rather than the approach you've suggested is that I have a whole bunch of code blocks to execute. I'll put my actual problem in the question and I'd appreciate it if you could take a look and see how I can restructure it – Matt Innes Sep 22 '16 at 07:57
  • @MattInnes Updated the answer. – mutbuerger Sep 22 '16 at 10:02
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    Marvellous! Thanks! This is just the syntax breakthrough I was looking for - I spent ages looking at the manual yesterday (http://orgmode.org/manual/noweb.html#noweb) but it was clearly the wrong manual - I didn't know about the Org babel ref card so double thanks for enlightening me! – Matt Innes Sep 22 '16 at 10:12