GH-145378: Use PyREPL as the default input console for pdb by gaogaotiantian · Pull Request #145379 · python/cpython

gaogaotiantian · 2026-03-01T01:56:10Z

Issue: Use pyrepl as the default input console for pdb #145378

gaogaotiantian · 2026-03-01T02:15:53Z

@pablogsal and @ambv as the original author for the new interactive shell. Could you take a look when you have some time, thanks!

read-the-docs-community · 2026-04-29T05:37:12Z

Documentation build overview

📚 cpython-previews | 🛠️ Build #32477993 | 📁 Comparing b04b192 against main (d71e3bc)

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4 files changed

±contents.html
±download.html
±whatsnew/3.15.html
±whatsnew/changelog.html

corona10 · 2026-04-29T15:18:09Z

+ stripped = len(origline) - len(line)
+ begidx = self.readline_wrapper.get_begidx() - stripped
+ endidx = self.readline_wrapper.get_endidx() - stripped
+ if begidx>0:


Suggested change
ifbegidx>0:
ifbegidx>0:

corona10 · 2026-04-29T15:20:22Z

+ self.message("*exit from pdb interact command*")
+ else:
+ with self._enable_rlcompleter(ns):
+ console = _PdbInteractiveConsole(ns, message=self.message)


This is not redundant declaration from L2486?

corona10 · 2026-04-29T15:39:14Z

+ console = _PdbInteractiveConsole(ns, message=self.message)
+ if self.pyrepl_input is not None:
+ from _pyrepl.simple_interact import run_multiline_interactive_console
+ self.message("*pdb interact start*")


Nit: Please declare as common variables
banner = "*pdb interact start*" exitmsg = "*exit from pdb interact command*"

corona10 · 2026-04-29T16:00:07Z

 return [e for e in self.displaying.get(self.curframe, {})
 if e.startswith(text)]

 def do_interact(self, arg):


defdo_interact(self, arg): """..."""ns= {**self.curframe.f_globals, **self.curframe.f_locals} console=_PdbInteractiveConsole(ns, message=self.message) banner="*pdb interact start*"exitmsg="*exit from pdb interact command*"ifself.pyrepl_inputisnotNone: console.run_interact(banner, exitmsg, use_pyrepl=True) else: withself._enable_rlcompleter(ns): console.run_interact(banner, exitmsg, use_pyrepl=False)

corona10 · 2026-04-29T16:05:18Z

+ if not os.getenv("PYTHON_BASIC_REPL"):
+ from _pyrepl.main import CAN_USE_PYREPL
+
+ return CAN_USE_PYREPL
+ return False


Suggested change
ifnotos.getenv("PYTHON_BASIC_REPL"):
from_pyrepl.mainimportCAN_USE_PYREPL
returnCAN_USE_PYREPL
returnFalse
ifos.getenv('PYTHON_BASIC_REPL'):
CAN_USE_PYREPL=False
else:
try:
from_pyrepl.mainimportCAN_USE_PYREPL
exceptModuleNotFoundError:
CAN_USE_PYREPL=False
returnCAN_USE_PYREPL

corona10 · 2026-04-29T16:20:05Z

+
+ self.pdb_instance = pdb_instance
+ self.prompt = prompt
+ self.console = code.InteractiveConsole()


So this should be something like this:
class_PdbInteractiveConsole(code.InteractiveConsole): def__init__(self, ns=None, message=None): self._message=messagesuper().__init__(locals=ns, local_exit=True) defwrite(self, data): ifself._messageisnotNone: self._message(data, end='') else: super().write(data) def_more_lines(self, text): # Generic Python multi-line completeness heuristic.# Strips pyrepl's trailing auto-indent before compiling.src=text.rstrip(" \t") n=len(src) ifn>0andtext[n-1] =='\n': text=srctry: code_obj=self.compile(text, "<stdin>", "single") except (OverflowError, SyntaxError, ValueError): lines=text.splitlines(keepends=True) iflen(lines) ==1: returnFalselast=lines[-1] return ((last.startswith((" ", "\t")) orlast.strip() !="") andnotlast.endswith("\n")) returncode_objisNone

corona10 · 2026-04-29T16:20:17Z

+
+ self.pdb_instance = pdb_instance
+ self.prompt = prompt
+ self.console = code.InteractiveConsole()


Suggested change
self.console=code.InteractiveConsole()
self.console=_PdbInteractiveConsole()

corona10

Left some comments to avoid making this fragile against future _pyrepl changes.
Let’s depend only on APIs that asyncio already uses.

bedevere-app · 2026-04-29T16:22:35Z

When you're done making the requested changes, leave the comment: I have made the requested changes; please review again.

gaogaotiantian · 2026-04-30T02:29:25Z

@corona10 I addressed most of the comments. There are a few things left to discuss:

for do_interact, we have to use run_multiline_interactive_console anyway. If you want a clearer entry I can put this logic into _PdbInteractiveConsole but we won't be able to get rid of the dependency of _pyrepl.
I added the history for pdb. I think one of the pain point users have is that pdb lost all the history when it restarts. For now pdb shares the same history file with python interpreter - I don't think that's a big deal right? It kind of makes sense. We can of course use a separate file, but the existing file is controlled by PYTHON_HISTORY env var and we support it natively if we just use the same history file.

corona10

for do_interact, we have to use run_multiline_interactive_console anyway. If you want a clearer entry I can put this logic into _PdbInteractiveConsole but we won't be able to get rid of the dependency of _pyrepl.

I think that it would be fine. asyncio already depends on it.

cpython/Lib/asyncio/__main__.py

Line 125 in 1695221

run_multiline_interactive_console,

I added the history for pdb.

Could we separate the PR for this? I think that it would be another feature.
I would like to see just pdb using pyrepl feature before the beta branch cut off, but this new feature would make another noise.

gaogaotiantian · 2026-04-30T03:33:19Z

Could we separate the PR for this? I think that it would be another feature.

Yeah sure. I was kind of hoping this could make it way it because that's one of the reasons that I wanted to use pyrepl for pdb - the inherited history. However, if you think it's a bit risky to onboard both, we can do only pyrepl for 3.15.

corona10

lgtm!

Let's fix upcoming bug during the beta period
Thanks you @gaogaotiantian

gaogaotiantian added 3 commits February 24, 2026 21:17

Use pyrepl for pdb
c23190e

Draft is done!
14ea66d

Remove unused import
7b01466

bedevere-appBot added the awaiting core review label Mar 1, 2026

bedevere-appBot mentioned this pull request Mar 1, 2026
Use pyrepl as the default input console for pdb #145378
Closed

blurb-itBotand others added 2 commits March 1, 2026 01:58

📜🤖 Added by blurb_it.
ce2fc9a

Add what's new entry
4cc5801

gaogaotiantian requested a review from AA-Turner as a code owner March 1, 2026 02:03

johnslavik self-requested a review March 2, 2026 19:54

tanloong reviewed Mar 6, 2026
View reviewed changes

Comment threadLib/pdb.py

tanloong mentioned this pull request Apr 1, 2026
PyREPL: Different Completion Behavior with GNU Readline #145392
Closed

gaogaotiantian added 2 commits April 28, 2026 22:14

Merge branch 'main' into pdb-pyrepl
f817371

Handle Ctrl+Z properly
5c3edfe

corona10 self-assigned this Apr 29, 2026

corona10 reviewed Apr 29, 2026
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Comment threadLib/pdb.py Outdated

corona10 reviewed Apr 29, 2026
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Comment threadLib/pdb.py Outdated

corona10 requested changes Apr 29, 2026
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bedevere-appBot added awaiting changes and removed awaiting core review labels Apr 29, 2026

Address comments and add history
9a783dc

gaogaotiantian requested a review from corona10 April 30, 2026 02:29

corona10 requested changes Apr 30, 2026
View reviewed changes

Remove history related code
b04b192

corona10 approved these changes Apr 30, 2026
View reviewed changes

bedevere-appBot added awaiting merge and removed awaiting changes labels Apr 30, 2026

gaogaotiantian merged commit 234c12c into python:mainApr 30, 2026
96 of 99 checks passed

bedevere-appBot removed the awaiting merge label Apr 30, 2026

ambv mentioned this pull request Jul 22, 2026
gh-154467: Fix empty (Pdb) prompt when attaching to a process with pdb -p #154469
Merged

-ifnotos.getenv("PYTHON_BASIC_REPL"):
-from_pyrepl.mainimportCAN_USE_PYREPL
-returnCAN_USE_PYREPL
-returnFalse
+ifos.getenv('PYTHON_BASIC_REPL'):
+CAN_USE_PYREPL=False
+else:
+try:
+from_pyrepl.mainimportCAN_USE_PYREPL
+exceptModuleNotFoundError:
+CAN_USE_PYREPL=False
+returnCAN_USE_PYREPL

	self.console=code.InteractiveConsole()
	self.console=_PdbInteractiveConsole()

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