Re: [BUG] shell sessions started outside of Babel broken

[Ihor Radchenko <yantar92@posteo.net>]

Jack Kamm <jackkamm@tatersworld.org> writes:

> Ihor Radchenko <yantar92@posteo.net> writes:
>
>> What is confusing is that `org-babel-execute-src-block' does not use
>> generic `org-babel-initiate-session'.
>
> I usually find myself confused whenever I am trying to remember
> where org-babel-LANG-initiate-session is run and what it's doing...

AFAIU, org-babel-LANG-initiate-session is ran the first time the session
is started. Its job is setting the comint to work with babel.

org-babel-LANG-prep-session is ran before a code block is executed
within a session. Its purpose is applying header args (like variable
bindings) and performing other immediate preparations to actually
execute the src block.

> In ob-shell's case, when I read the lisp code it seems like
> org-babel-prompt-command would get called every time
> org-babel-execute:shell runs (via org-babel-sh-initiate-session).

No. `org-babel-sh-initiate-session' has
   (or (org-babel-comint-buffer-livep session)
       ...)

So, it does nothing when the session buffer is already present.

> But that's not how the behavior seems when I use it, e.g. if using a
> M-x shell session, the prompt isn't changed after executing a src
> block.

Because `org-babel-comint-buffer-livep' will return t for a buffer
created by M-x shell. It may or may not be a bug.

We can, for example, make `org-babel-comint-buffer-livep' return nil
unless a special buffer-local indicator is set upon evaluating
`org-babel-sh-initiate-session'.

However, it may be tricky in general case because what we have to do
when creating a new session buffer may or may not be the same with what
we have to do when M-x shell buffer exists already.

>> We may, however, allow an extra header arg to set the prompt regexp
>> manually. Would it make sense?
>
> It does feel a little confusing, but I don't have any better ideas at
> the moment.
>
> To clarify -- would the header arg be for setting
> comint-prompt-regexp, org-babel-prompt-command, both, or something
> else?

I imagine that the header arg will be setting comint-prompt-regexp.

-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
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