Can't change sys.ps1 in IDLE

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I've recently heard that you can change the prompt in python by changing variable sys.ps1. So I've decided to open IDLE, and write something like that:

>>> import sys
>>> sys.ps1 = ":::"

However, that created a new variable and nothing changed (prompt was still ">>>") - I rebooted IDLE and checked is this variable read by python... Nope:

>>> sys.ps1
Traceback (most recent call last):
  File "<pyshell#1>", line 1, in <module>
    sys.ps1
AttributeError: module 'sys' has no attribute 'ps1'

So, how do I change the prompt in python? NOTE: The other functions/variables of sys module were read properly.

ps1 python-idle prompt python
2 Answers

The prompt strings specifying the primary and secondary prompt (their initial values in this case are >>> and ... ) of the interpreter are only defined if the interpreter is in interactive mode and IDLE is more or less an integrated development environment for Python

Python interactive mode: Python interactive mode

sys.ps1 doc

user_70132630

See issue #13657, "IDLE doesn't recognize resetting sys.ps1", on the Python bug tracker. It was opened in 2011 and is still unresolved (as of this writing). So it is not possible to change the prompt from within IDLE's Python shell simply because IDLE does not support that.

Update (less than 24 hours later): The issue is now closed. In the upcoming version of IDLE, to be released with Python 3.10, prompts will be displayed differently. See comment by IDLE developer Terry Jan Reedy above. A setting to change the prompt may be added in the future.

In the current and earlier Python/IDLE releases, the prompt can be customized before starting IDLE, but not while running it. You'd need a little start-up script that does this:

import sys
sys.ps1 = '::: '
import idlelib.idle

The reason you get that error message (module 'sys' has no attribute 'ps1') is because the Python shell that IDLE presents to you is not actually in "interactive" mode. And only then is sys.ps1 defined. You'd see the same error message if you tried to access sys.ps1 in any other Python program that is directly executed. In this case, that Python program is IDLE itself.

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