I doubt it is Python specific, and I don't know why it would work in some
places and not others. For me, the two character name does not work in
elisp, but 1 or 3 does. I agree that seems buggy.

The origin of the problem is here:

#+BEGIN_SRC emacs-lisp
(list
 (string-match (org-babel-noweb-wrap) "<<A>>")
 (string-match (org-babel-noweb-wrap) "<<Ah>>")
 (string-match (org-babel-noweb-wrap) "<<Ahh>>"))
#+END_SRC

#+RESULTS:
| 0 | nil | 0 |

my regex fu is not adequate to identify the problem:

#+BEGIN_SRC emacs-lisp
(org-babel-noweb-wrap)
#+END_SRC

#+RESULTS:
: <<\([^
: ].+?[^ ]\|[^
: ]\)>>

That function is used in org-babel-expand-noweb-references.


It is somewhat luck that I found that, I was tracing
org-babel-expand-noweb-references to see where it was failing, and walked
through that line to see it failed on "Ah", and worked on longer names.

John

-----------------------------------
Professor John Kitchin
Doherty Hall A207F
Department of Chemical Engineering
Carnegie Mellon University
Pittsburgh, PA 15213
412-268-7803
@johnkitchin
http://kitchingroup.cheme.cmu.edu



On Mon, Feb 4, 2019 at 8:40 AM Emmanuel Charpentier <emm.charpentier@free.fr>
wrote:

> Le lundi 04 février 2019 à 08:11 -0500, John Kitchin a écrit :
>
> The problem may be the name is only two characters long. Try Ahh instead.
> That works for me.
>
>
> Indeed. Nice catch ; how did you find this ?
>
> Since this doesn't happen with emacs-lisp or Sage, and since nothing in
> the docs I've read so far suggests anything about the length of a block
> identifier, I consider this a bug in the Python language support code. What
> do you think ? Any hint ?
>
> Thanks a lot !
>
> --
> Emmanuel Charpentier
>
> John
>
> -----------------------------------
> Professor John Kitchin
> Doherty Hall A207F
> Department of Chemical Engineering
> Carnegie Mellon University
> Pittsburgh, PA 15213
> 412-268-7803
> @johnkitchin
> http://kitchingroup.cheme.cmu.edu
>
>
>
> On Mon, Feb 4, 2019 at 7:00 AM Emmanuel Charpentier <
> emm.charpentier@free.fr> wrote:
>
> Seen in `org-mode' version `9.2'.
>
> Using `noweb' syntax works OK with `emacs-lisp':
>
> ┌────
> │ #+name: a
> │ #+begin_src emacs-lisp
> │   (setq L (append L (list i)))
> │ #+end_src
> │
> │ #+name: b
> │ #+begin_src emacs-lisp :noweb yes :exports both
> │   ;; Lisp version
> │   (setq L nil)
> │   (dotimes (i 5) <<a>>)
> │   L
> │ #+end_src
> └────
>
> This gives :
>
> ┌────
> │ (setq L (append L (list i)))
> └────
>
> ┌────
> │ ;; Lisp version
> │ (setq L nil)
> │ (dotimes (i 5) )
> │ L
> └────
>
> The `noweb' syntax also works with `Sage' (a symbolic maths oriented
> Python derivative):
>
> ┌────
> │ #+name: Aaarghhh
> │ #+begin_src sage
> │   L.append(i)
> │ #+end_src
> │
> │ #+name: Berde
> │ #+begin_src sage :noweb yes :exports both
> │   ## Python version
> │   L=[]
> │   for i in range(1,6):
> │       <<Aaarghhh>>
> │   L
> │ #+end_src
> └────
>
> wich gives :
>
> ┌────
> │ L.append(i)
> └────
>
> ┌────
> │ ## Sage version
> │ L=[]
> │ for i in range(1,6):
> │
> │ L
> └────
>
> But using the same syntax in Python fails miserably:
>
> ┌────
> │ #+name: Ah
> │ #+begin_src python
> │   L.append(i)
> │ #+end_src
> │
> │ #+name: Beee
> │ #+begin_src python :noweb yes :exports both
> │   ## Python version
> │   L=[]
> │   for i in range(1,6):
> │       <<Ah>>
> │   L
> │ #+end_src
> └────
>
> ┌────
> │ L.append(i)
> └────
>
> ┌────
> │ ## Python version
> │ L=[]
> │ for i in range(1,6):
> │     <<Ah>>
> │ L
> └────
>
> ┌────
> │ []
> └────
>
>
> It *seems* that the "Ah" block is not expanded.
>
> The code itself should be sound *if* it expanded:
>
> ┌────
> │ #+name: B0
> │ #+begin_src python :exports both
> │   L=[]
> │   for i in range(1,6):
> │       L.append(i)
> │   L
> │ #+end_src
> └────
>
> ┌────
> │ L=[]
> │ for i in range(1,6):
> │     L.append(i)
> │ L
> └────
>
> ━━━━━━━━━━━━━━━
>  1  2  3  4  5
> ━━━━━━━━━━━━━━━
>
> During the compilation of the source of this mail, the following is
> printed in the `*Python*' buffer:
>
> ┌────
> │ >>> L.append(i)
> │ >>>
> │ >>> open('/tmp/babel-OJSsxf/python-dVESY4', 'w').write(str(_))
> │ >>>
> │ >>>
> │ >>> 'org_babel_python_eoe'
> │ 'org_babel_python_eoe'
> │ >>> ## Python version
> │ ... L=[]
> │ >>> for i in range(1,6):
> │ ...     <<Ah>>
> │   File "<stdin>", line 2
> │     <<Ah>>
> │      ^
> │ SyntaxError: invalid syntax
> │ >>>
> │ >>> L
> │ []
> │ >>>
> │ >>> open('/tmp/babel-OJSsxf/python-9NR46u', 'w').write(str(_))
> │ >>>
> │ >>>
> │ >>> 'org_babel_python_eoe'
> │ 'org_babel_python_eoe'
> │ >>> L=[]
> │ >>> for i in range(1,6):
> │ ...     L.append(i)
> │ ...
> │ >>> L
> │ [1, 2, 3, 4, 5]
> │ >>>
> │ >>> open('/tmp/babel-OJSsxf/python-fW5gK0', 'w').write(str(_))
> │ >>>
> │ >>>
> │ >>> 'org_babel_python_eoe'
> │ 'org_babel_python_eoe'
> │ >>>
> └────
>
> The source code of this mail is attached.
>
> --
> Emmanuel Charpentier
>
>