gh-134746: implement Ctrl+Alt+L clear display keymap in pyREPL #138521

sharmaigne · 2025-09-05T06:25:45Z

Changes:

added a clear_all() method to console files that does what clear() does + clears scrollback
added the Ctrl+Alt+L keymap

Note:

description of clear_display behavior: Clear the screen and, if possible, the terminal's scrollback buffer, then redraw the current line, leaving the current line at the top of the screen.
Manually tested for unix but not yet tested for windows

Issue: Ctrl+Alt+L is broken after upgrading to Python 3.13 #134746

python-cla-bot · 2025-09-05T06:25:49Z

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bedevere-app · 2025-09-05T06:25:50Z

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StanFromIreland

Please undo all of the unrelated changes.

bedevere-app · 2025-09-05T06:36:46Z

Most changes to Python require a NEWS entry. Add one using the blurb_it web app or the blurb command-line tool.

If this change has little impact on Python users, wait for a maintainer to apply the skip news label instead.

bedevere-app · 2025-09-05T06:49:42Z

Most changes to Python require a NEWS entry. Add one using the blurb_it web app or the blurb command-line tool.

If this change has little impact on Python users, wait for a maintainer to apply the skip news label instead.

bedevere-app · 2025-09-05T06:52:19Z

Most changes to Python require a NEWS entry. Add one using the blurb_it web app or the blurb command-line tool.

If this change has little impact on Python users, wait for a maintainer to apply the skip news label instead.

sharmaigne · 2025-09-05T07:04:21Z

Please undo all of the unrelated changes.

Done! Sorry, forgot to turn off the formatter.

bedevere-app · 2025-09-05T07:04:34Z

Most changes to Python require a NEWS entry. Add one using the blurb_it web app or the blurb command-line tool.

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into fix-issue-134746

sharmaigne · 2025-09-05T07:50:30Z

cc @corona10

corona10 · 2025-09-05T07:57:32Z

@ambv @pablogsal

She asked me onsite whether she needs to add a test case for this.
If there isn’t already such a test, would it be okay for her to open a new issue for it?

Lib/_pyrepl/console.py

Co-authored-by: Donghee Na <[email protected]>

corona10 · 2025-09-05T08:15:38Z

ERROR: test_multiline_edit (test.test_pyrepl.test_pyrepl.TestPyReplOutput.test_multiline_edit)

Traceback (most recent call last):
File "/Users/admin/actions-runner/_work/cpython/cpython/Lib/test/test_pyrepl/test_pyrepl.py", line 686, in test_multiline_edit
reader = self.prepare_reader(events)
File "/Users/admin/actions-runner/_work/cpython/cpython/Lib/test/test_pyrepl/test_pyrepl.py", line 624, in prepare_reader
console = FakeConsole(events)
TypeError: Can't instantiate abstract class FakeConsole without an implementation for abstract method 'clear_all'

sharmaigne · 2025-09-05T08:42:44Z

@corona10 reran the test suite, should be good now

chris-eibl · 2025-09-14T17:34:59Z

Lib/_pyrepl/windows_console.py

 MOVE_UP = "\x1b[{}A"
 MOVE_DOWN = "\x1b[{}B"
 CLEAR = "\x1b[H\x1b[J"
+CLEAR_ALL= "\x1b[3J\x1b[2J\x1b[H"


Suggested change

CLEAR_ALL= "\x1b[3J\x1b[2J\x1b[H"

CLEAR_ALL= "\x1b[H\x1b[3J\x1b[J"

Using this works for me in the new virtual console on Windows. Also more symmetric to the CLEAR above.

chris-eibl · 2025-09-14T17:40:46Z

Lib/_pyrepl/unix_console.py


+    def clear_all(self) -> None:
+        """Clear screen and scrollback buffer."""
+        self.__write("\x1b[3J\x1b[2J\x1b[H")


Suggested change

self.__write("\x1b[3J\x1b[2J\x1b[H")

self.__write("\x1b[H\x1b[3J\x1b[2J")

Altough both worked for me on Ubuntu 24.0.4.3 LTS, maybe starting with \x1b[H is better?
Since it is used like so for clear

cpython/Lib/_pyrepl/terminfo.py

Line 176 in 1c984ba

"clear": b"\x1b[H\x1b[2J", # Clear screen and home cursor

cpython/Lib/_pyrepl/terminfo.py

Line 250 in 1c984ba

"clear": b"\x1b[H\x1b[J", # Clear screen and home cursor (different from ansi!)

And for symmetry with Windows (see below)?

chris-eibl · 2025-09-14T17:48:07Z

Lib/_pyrepl/unix_console.py

+    def clear_all(self) -> None:
+        """Clear screen and scrollback buffer."""
+        self.__write("\x1b[3J\x1b[2J\x1b[H")
+        self.clear()


This writes another "clear" sequence to the terminal, which did not play nicely on Ubuntu 24.0.4.3 LTS for me.
Replacing this with

self.__gone_tall = 1 self.__move = self.__move_tall self.posxy = 0, 0 self.screen = []

did work for me, though. But I suggest to extract that in a new method (maybe called _clear?) to avoid repetition. Can be used in

cpython/Lib/_pyrepl/unix_console.py

Lines 350 to 353 in 1c984ba

self.posxy = 0, 0

self.__gone_tall = 0

self.__move = self.__move_short

self.__offset = 0

and the self.screen = [] a few lines above, too.

chris-eibl · 2025-09-14T17:51:55Z

Lib/_pyrepl/windows_console.py

+    def clear_all(self) -> None:
+        """Clear screen and scrollback buffer."""
+        self.__write(CLEAR_ALL)
+        self.clear()


See my comments wrt to Unix above. Although on Windows this does no harm for me, I'd suggest to extract that, too. Please note that #138732 should be merged first, though, since this is the reason for self.screen = [""] here vs self.screen = [] in prepare (see #138732 (comment)).

chris-eibl · 2025-09-14T18:21:04Z

In the legacy console on Windows this command is not executed, because in

cpython/Lib/_pyrepl/windows_console.py

Lines 471 to 481 in 1c984ba

    
           elif key == "\x00": 
        
               # Handle special keys like arrow keys and translate them into the appropriate command 
        
               key = VK_MAP.get(key_event.wVirtualKeyCode) 
        
               if key: 
        
                   if key_event.dwControlKeyState & CTRL_ACTIVE: 
        
                       key = f"ctrl {key}" 
        
                   elif key_event.dwControlKeyState & ALT_ACTIVE: 
        
                       # queue the key, return the meta command 
        
                       self.event_queue.insert(Event(evt="key", data=key)) 
        
                       return Event(evt="key", data="\033")  # keymap.py uses this for meta 
        
                   return Event(evt="key", data=key)

VK_MAP is missing all regular keys (at least L 0x4C needs to be added, see here for all possible codes)
the if - elif does not handle a key_event like this that has both CTRL_ACTIVE and ALT_ACTIVE set.

chris-eibl · 2025-09-23T14:57:33Z

To smoothly work on Windows in the virtual console (AKA Windows Terminal), #139263 is needed, too.

sharmaigne requested review from pablogsal, lysnikolaou and ambv as code owners September 5, 2025 06:25

bedevere-app bot added the awaiting review label Sep 5, 2025

bedevere-app bot mentioned this pull request Sep 5, 2025

Ctrl+Alt+L is broken after upgrading to Python 3.13 #134746

Open

StanFromIreland reviewed Sep 5, 2025

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sharmaigne added 2 commits September 5, 2025 14:47

feat: add clear_all function that clears screen and scrollback

d2eab6f

feat: add clear_display keymap (\C-\M-l)

17ecbe7

sharmaigne force-pushed the fix-issue-134746 branch from 510c8e7 to 17ecbe7 Compare September 5, 2025 06:49

fix: add clear_all method to console class

457e1e2

Merge branch 'main' into fix-issue-134746

236dd13

sharmaigne added 2 commits September 5, 2025 15:07

chore: Add NEWS entry

14422a4

Merge branch 'fix-issue-134746' of https://github.com/sharmaigne/cpython

c0f2687

into fix-issue-134746

sharmaigne requested a review from StanFromIreland September 5, 2025 07:08

corona10 reviewed Sep 5, 2025

View reviewed changes

Lib/_pyrepl/console.py Show resolved Hide resolved

refactor: specify that clear_all is an abstract method

d9fc1c9

Co-authored-by: Donghee Na <[email protected]>

sharmaigne requested a review from corona10 September 5, 2025 08:01

Merge branch 'main' into fix-issue-134746

eb8b022

test: add clear_all method to FakeConsole

8da3576

chris-eibl reviewed Sep 14, 2025

View reviewed changes

ambv added the topic-repl Related to the interactive shell label Sep 15, 2025

	CLEAR_ALL= "\x1b[3J\x1b[2J\x1b[H"
	CLEAR_ALL= "\x1b[H\x1b[3J\x1b[J"

	self.__write("\x1b[3J\x1b[2J\x1b[H")
	self.__write("\x1b[H\x1b[3J\x1b[2J")

	self.posxy = 0, 0
	self.__gone_tall = 0
	self.__move = self.__move_short
	self.__offset = 0

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gh-134746: implement Ctrl+Alt+L clear display keymap in pyREPL #138521

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