Python 3.13: gnureadline appears to no longer be used

[milosivanovic]

Bug report

Bug description:

Tested in 3.12:
In the <=3.12 Python REPL on Linux, pressing CTRL+R invokes gnureadline and shows:

(reverse-i-search)`':

Tested in 3.13:
In the 3.13 Python REPL on Linux, pressing CTRL+R does not appear to invoke gnureadline and shows:

(r-search `')

---

Additionally, with nothing in the command history, typing a few characters in the 3.13 REPL (without pressing enter) and then using the up/down arrow keys moves the cursor to the start and end of the line. In 3.12 (any in any other software that uses gnureadline), pressing up/down in this scenario did nothing and is the expected behaviour.

Was gnureadline removed in 3.13 in favour of an in-house implementation that doesn't mirror the featureset? If so, is it possible to restore the previous behaviour from <=3.12? This used to be able to be done with ludwigschwardt/python-gnureadline#62 but this no longer appears to work in 3.13.

CPython versions tested on:

3.12, 3.13

Operating systems tested on:

Linux, macOS

[nineteendo]

The old REPL can still be activated: https://docs.python.org/3/using/cmdline.html#envvar-PYTHON_BASIC_REPL

[ludwigschwardt]

Out of interest, how much does the new REPL still depend on readline?

It is explicitly mentioned as a dependency in the docs linked above, and I see that the code in Lib/_pyrepl still imports rlcompleter but I can't tell at a glance how much functionality has been reimplemented in Python. Is there a summary somewhere?

[Architector4]

Not sure if I make this a separate issue or as a comment here, but another behavioral difference with CTRL+R search in the new REPL is that after looking up a line, pressing ENTER only closes the search and returns back to the normal mode, and then you need to press ENTER again to actually input the command.

That has been messing with my muscle memory as now I have to double-tap the key each time lol

[milosivanovic]

@Architector4 I agree, and I don't like it either.

I think there are and will be lots of people in the same boat who will question this change. Many linux tools use GNU readline, so having to continuously switch between how Python's arbitrary readline implementation treats ENTER vs the standard GNU implementation which is present in so many tools makes for an incredibly frustrating command-line experience.

I personally stopped using the new REPL by setting PYTHON_BASIC_REPL=1. I hope that the Python team can achieve reasonable feature parity with GNU readline in 3.13+ or at the very least let us have PYTHON_BASIC_REPL=1 indefinitely. As mentioned, I think having to continuously learn/unlearn how to use CTRL+R depending on what tool I am using is quite inconvenient.

[ambv]

PYTHON_BASIC_REPL is indeed planned to be around forever. The CTRL+R difference is deliberate, to let you edit a search result before executing the command.