Python.exe in Emacs26 for M$ Windows - REPL problem

[Eduardo Ochs]

Hello list,

big message, split in two parts.


1. Introduction
===============
I sometimes use Emacs and eev to present some principles of Free
Software - for example this, but in practice:
https://www.gnu.org/software/emacs/emacs-paper.html#SEC29 - to total
newbies, but I always have to tell them that the nicest feature of
eev, called "eepitch", currently doesn't work well on their Windows
machines...  it is explained here:

  http://angg.twu.net/eev-intros/find-eev-quick-intro.html#6
  http://angg.twu.net/eev-intros/find-eepitch-intro.html

and there's a demo of it here:

  https://www.youtube.com/watch?v=86yiRG8YJD0&t=956s

The problem is that downloading and installing Lua, Python, Bash or
MinGW/MSYS2 on Windows is non-trivial and people have very short
attention spans, so I sort of "don't have the time" to install any of
those things on their machines - I mean, before they lose focus.

Two days ago when I helped another newbie to install Emacs in her
machine from this .zip,

  http://gnu.c3sl.ufpr.br/ftp/emacs/windows/emacs-26/emacs-26.3-x86_64.zip

and I noticed that it comes with a python.exe, a tclsh.exe and a
wish.exe.  I didn't have time to test these .exes on her machine, and
I don't have access to a W$ box, but earlier today I asked for help in
the #emacs channel and a person there - Jeff Carlson - ran some sexps
for me in his W$ laptop.  His Emacs was installed using Chocolatey, so
his paths may be a bit atypical, but this

  (find-file "C:/ProgramData/chocolatey/lib/Emacs/tools/emacs/bin/")

opened the directory with python.exe, tclsh.exe, and wish.exe, and I
expected that this

  (switch-to-buffer
   (make-comint
    "python.exe"
    "C:/ProgramData/chocolatey/lib/Emacs/tools/emacs/bin/python.exe"))

would enter a Python REPL in comint... but no, we got these errors:

  Could not find platform independent libraries <prefix>
  Could not find platform dependent libraries <exec_prefix>
  Consider setting $PYTHONHOME to <prefix>[:<exec_prefix>]
  ImportError: No module named site

  Process python.exe exited abnormaly with code 1



2. Questions
============
1. Where can I find the rationale for why there are a python.exe, a
   tclsh.exe, and a wish.exe in Emacs26 for Windows?

2. This is the variable that points to their directory, right?

     (describe-variable 'exec-directory)

3. How are these .exes meant to be called?  What are the main
   functions and .el files that call them?  Is `exec-directory' a part
   of the default path in Windows?

4. Is (switch-to-buffer (make-comint ... ...)) supposed to work with
   them?  Can someone test that with python.exe, tclsh.exe, and
   wish.exe and check that we get working REPLs?



Many, many thanks in advance =),
  Eduardo Ochs
  http://angg.twu.net/emacsconf2019.html
  http://angg.twu.net/#eev