From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jack Kamm <jackkamm@gmail.com>
Subject: Re: [PATCH] (Tiny) Tweak Python session null return value
Date: Mon, 17 Feb 2020 11:05:44 -0800
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To: John Kitchin <jkitchin@andrew.cmu.edu>
Cc: Bastien <bzg@gnu.org>, org-mode-email <emacs-orgmode@gnu.org>

Hi John,

John Kitchin <jkitchin@andrew.cmu.edu> writes:

> I think None is correct. If you don't specify a return value in Python,
> then a function returns None. I would expect that to happen in a Python
> block too.

Hmm, OK, thanks for your intuition, it's useful feedback.

Working this out loud, I was considering the following sort of block:

#+begin_src python :session :results value
  if some_condition:
      True
  else:
      False
#+end_src

#+RESULTS:
: None

Ideally, it would return True/False, but the current implementation
cannot grab that result unfortunately. (In its defense, it at least
doesn't crash like it did before).

I was thinking not printing anything at all under "#+RESULTS" would be
less surprising than printing "None". But both are admittedly surprising
at first.

I agree your preference of returning "None" is the more technically
consistent behavior though.

I don't want to rush a decision now, I think I need to gather more user
feedback after the 9.4 release. I'll ask Bastien to revert that commit
and put this off to 9.5, rather than writing an updated NEWS entry like
he asked.

Either way, we'll need to update Worg to clearly document what's going
on here.