How to override ":eval no" in call lines?

[Sebastien Vauban <sva-news-D0wtAvR13HarG/iDocfnWg@public.gmane.org>]

Hello,

In a long document, I must have ":eval no" at file level, as this is the
common setting for most code blocks. However, how do I unset that for
some call lines.

Export this ECM (to HTML, for example) and see for yourself that it does
not seem evident...

--8<---------------cut here---------------start------------->8---
#+TITLE:     ECM to be exported

#+PROPERTY:  eval no
#+PROPERTY:  results none

* Results
  :PROPERTIES:
  :exports:  results
  :results:  replace
  :END:

** Square

Here nothing gets executed: neither the code block, nor the call lines...

#+name: square
#+begin_src emacs-lisp :tangle no :var x=1
(* x x)
#+end_src

2 x 2 = call_square(x=2).

3 x 3 = call_square[:eval yes](x=3).

** Plus

Here, ":eval yes" (or even ":eval foo" FWIW) allows the code block to get
executed at export:

#+name: plus
#+begin_src emacs-lisp :tangle no :var x=4 :eval foo
(+ x x)
#+end_src

But none of the call lines gets executed...

5 + 5 = call_plus(x=5).

6 + 6 = call_plus[:eval yes](x=6).

So, how do I override the ":eval no" specified at the file level?
--8<---------------cut here---------------end--------------->8---

Any idea?

Best regards,
  Seb

-- 
Sebastien Vauban