I am using emacs 25.2.1

Look at the following simple code:

import sys

def yes_no_barrier(message):
    print(message + ' (yes/no): ')
    while 1:
        s=str(input(message + ' (yes/no): '))
        if s == 'yes':
            return 'yes'
        if s == 'no':
            return 'no'
        print('please enter yes or no')

yes_no_barrier('Are you tall?')

I tried to run the code in a real terminal (Python 3.6.4) and it was worked. Then I tried to run it inside emacs, first using C-c C-p for opening a Python console, and then, from the .py buffer, pressing C-c C-c.

I tried no and the code worked, I then tried yes and other strings and the Python buffer froze, forcing me to press C-g. I have no clue what there is special with no except for being shorter than the word yes.

Since I was always getting the same strange behaviour I dug the web and I tried random stuff, finally solving the issue.

Here there is the full Python configuration which fixed the issue, not sure which part did it.

;I also installed from list-packages python-mode
(require 'python)
(add-hook 'python-mode-hook
      (lambda ()
        (setq indent-tabs-mode t)
        (setq tab-width 4)
        (setq python-indent 4)))

(setq scroll-down-aggressively 1)

(defun python-shell-parse-command ()
   "Return the string used to execute the inferior Python process."
   "/usr/bin/python3 -i")

(setq py-python-command "python3")
(setq py-shell-name "python3")
(setq python-shell-interpreter "python3")

I was happy with this magic code, but I had to switch to IPython (6.2.1, still using Python 3.6.4) since I wanted to solve this other problem, described here.

That problem was solved but now I have back the same problem with input() which I described before: no works but yes makes the console freeze.

I tried the obvious modifications to my configuration, which are listed here:

(setenv "IPY_TEST_SIMPLE_PROMPT" "1") ;for fixing a problem with IPython not showing correctly

(setq python-shell-interpreter "/usr/local/bin/ipython"
   python-shell-interpreter-args "--profile=dev -i")

(defun python-shell-parse-command () "/usr/local/bin/ipython
--profile=dev -i")

(setq py-python-command "ipython")
(setq py-shell-name "ipython")
(setq python-shell-interpreter "ipython")

But the error this time is not disappearing.

Can you help me, please? Does the code work in your emacs?

EDIT1: I just realised that the problem does not arise when I press return but when I type the third letter of a word, so if I type yes, then I will not be able to use the console anymore. For instance I will not be able to type backspace and I will be forced to press C-g to send a keyboard interrupt and make the console usable again.

EDIT2: I removed the line (require 'python) and now I type M-x ipython. The console that will appear works and I can send commands to it with C-c C-c. The console that I open with C-c C-p does not work. So I can consider solved my problem.

  • Often the reason for problems of this kind is that one side expects an indication of line ending, while another sides doesn't send it. Not sure if this is the issue here, but I'd try to see what function is bound to RET (i.e. C-h k RET and then instrument this function for debugging: gnu.org/software/emacs/manual/html_node/elisp/… then try to reproduce the buggy behavior and step through the code until you see what's causing to get stuck.
    – wvxvw
    Commented Feb 24, 2018 at 20:26
  • Thanks! I just realized that the problem is not the return key, see the edit
    – Nisba
    Commented Feb 24, 2018 at 20:46

1 Answer 1


AFAIK this is caused by an change of IPython which seems not to accept multiline pasting any more.

Here is some info: https://github.com/ipython/ipython/issues/9816

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